UNIVERSITY OF CALI AT LOS ANGE THE GIFT OF MAY TREAT MORRISON IN MEMORY OF ALEXANDER F MORRISON POPULAR ASTRONOMY SIMON NEWCOMB, LL,D,, UOFKSSOR U. S. NATAL OBSERVATORY, AUTHOR OF " THE A B C OF FINANCE ' With One Hundred and Twelve Engravings, and Five Maps of the Stars. 8vo, Cloth, $2 SO. The great reputation which the author of this work has merited and enjoys, both in this country and in Europe, is a sufficient guarantee of its excellence. * * * He has dwelt especially upon those topics which have just now a popular and philosophic interest, carefully employing such Ian- guage and such simple explanations as will be intelligible without labori ous study. Technical terms have as much as possible been avoided. Such as were employed of necessity, and many that occur elsewhere, have been fully explained in a copious glossary at the end of the book. With its abundant aid, the reader cannot fail to derive both pleasure and entertain- ment from the study of what is the most ancient as well as the most ele- vating and inspiring of all the natural sciences. * * * Professor Newcomb, throughout his whole volume, preserves his well - known character as a writer who, in treating of scientific subjects, fully understands the art of bringing them within the range of popular comprehension. Although his book is a valuable addition to scientific literature, it is fully calculated to hold the attention of the general reader. N. Y, Times. The problem of adapting the facts and principles of a most intricate science to the understanding of the ordinary reader has been earnestly undertaken and successfully solved in this work. * * * The entire volume bespeaks the well-known ability of its author, and furnishes a new title to his world-wide reputation. Boston Transcript. cGmV s \Popular Astronomy. Professor Newcomb carefully avoids the temptation held out to him bj many parts of the subject to write for effect ; he keeps always faithfully to his purpose, setting forth, with respect to every subject discussed, the history of the investigations made, the positive, certain results attained, and the conjectures which astronomers have founded upon these results, together with the reasoning on which each conjecture rests and the objec- tions that exist to its acceptance.- He is, in a word, singularly conscien- tious and perfectly frank ; but the subject itself is so full of wonders that even when treated in this calm, scientific spirit, its discussion is entran- cingly interesting ; and Professor Newcomb's work, written as it is in a perfectly clear, simple, and direct style, is likely, we think, to become more than ordinarily popular. N. Y. Evening Post. The book has the great merit of a simplicity that never wearies the reader's attention. It presents the newest as well as the old discoveries, and is free from the errors which mar most of the treatises on astronomy that are designed for non-professional use. Ordinary readers will appre- ciate the circumstance that no mathematical formulas are employed. * * * In each division of the work the history of discovery is made to subserve the purpose of explanation. * * * Step by step the reader is led toward the theories of Copernicus, Kepler, and Newton, and is shown why and how their hypotheses best explained the facts of observation, which have been already detailed. A great advantage is thereby gained over ordinary trea- tises of astronomy, which present the recent knowledge first, and either give the facts unsupported, or press their acceptance by means of the stern logic of geometry. In Professor Newcomb's work the great truths grow slowly, and can be measured as they grow. N. Y. Tribune. The author is a master of all the theories and lore of his beloved sci- ence, and he has at command the unrivalled instruments of the United States Naval Observatory at Washington. He is an unwearied investiga- tor and professional enthusiast (in the best sense of the word), and writes an English which all people can understand. Parade and pedantry are wholly absent from this work. N. Y. Journal of Commerce. Any person of average intelligence can take this volume, and in a month or two become an intelligent observer of the worlds around us. Christum wer, N. Y. N'ewcomVs Popular Astronomy. This is one of those books which deserve and are sure to receive a hearty welcome : a full and accurate resume of the subject treated, prepared and brought down to date by one who is a master of the science, and at tke same time a clear and vigorous writer. It is a book which ought to be in the library of every intelligent person as a standard authority, safely to be referred to on any topic within its scope ; and yet it is not heavy or dull, but, for the most part, as readable and interesting as a work of fiction. * * * The work is neither abstruse and dry, nor, on the other hand, is it puerile and fanciful, as sometimes happens when savans attempt to popu- larize their favorite sciences, and write down to what they conceive to be the level of the common intelligence. The plan is logical, the due propor- tions of different portions of the subject are observed, and the style is clear, forcible, and sufficiently picturesque and stimulating to keep the attention without effort. Professor CHARLES A. YOUNG, in the Independent, N.Y. It is only rarely that a great mathematical astronomer condescends to write books for the people ; and if he does, in four cases out of five, what he writes is unintelligible to all but a very few. Investigators seldom have either the disposition or ability to communicate what they know to the world in general. To this rule, however, there are happy exceptions ; and among them must be counted Professor Newcomb, whose Popular Astron- omy is undoubtedly the best work of its kind in the English language. Its arrangement is logical, its statements are accurate, its reasonings clear, and its style simple, perspicuous, and sufficiently picturesque. Through- out the book it is everywhere evident that great care has been taken to secure exact and perfect truthfulness of representation: facts are kept distinct from fancies, and theories and speculations stand for just what they &re. Sunday School Times, Philadelphia. PUBLISHED BY HARPER & BROTHERS, NEW YORK. ~ Sent by mail, postage prepaid, to any part of the United States, on receipt of $2 00. THE CONSTELLATIONS OF ORION AND TAURUS. NOTES. Star a in Tanrns is red, has eight, metals; moves east (page 227). At o above tip of right horn is the Crab Nebula (page 219). In Orion, a is variable, nan five metals ; recedes 22 miles per second. /?, 6, e, f , p, etc., are double stars, the component parts of various colors and magnitudes (page 212, note). \ and i are triple ; PYXHI THI AFAnHTHI ASTPADTOYSHI KAI 428055 PREFACE. ALL sciences are making an advance, but Astronomy is moving at the double-quick. Since the principles of this science were settled by Copernicus, four hundred years ago, it has never had to beat a, retreat. It is re- written not to correct material errors, but to incorporate new discoveries. Once Astronomy treated mostly of tides, seasons, and telescopic aspects of the planets; now these are only primary matters. Once it considered stars as mere fixed points of light ; now it studies them as suns, determines their age, size, color, movements, chemical constitution, and the revolution of their planets. Once it considered space as empty ; now it knows that every cubic inch of it quivers with greater intensity of force than that which is visible in Niagara. Every inch of surface that can be conceived of between suns is more wave-tossed than the ocean in a storm. The invention of the telescope constituted one era in Astronomy; its perfection in our day, another; and the discoveries of the spectroscope a third no less impor- tant than either of the others. While nearly all men are prevented from practical experimentation in these high realms of knowledge, few viii PREFACE. have so little leisure as to be debarred from intelligently enjoying the results of the investigations of others. This book has been written not only to reveal some of the highest achievements of the human mind, but also to let the heavens declare the glory of the Divine Mind. In the author's judgment, there is no gulf that separates science and religion, nor any conflict where they stand together. And it is fervently hoped that any one who comes to a better knowledge of God's works through reading this book, may thereby come to a more intimate knowledge of the Worker. I take great pleasure in acknowledging my indebted- ness to J. M. Yan Vleck, LL.D., of the U. S. Nautical Almanac staff, and Professor of Astronomy at the Wes- leyan University, for inspecting some of the more im- portant chapters ; to Dr. S. S. White, of Philadelphia, for telescopic advantages ; to Professor Henry Draper, for furnishing, in advance of publication, a photograph of the sun's corona in 1878 ; and to the excellent work on "Popular Astronomy," by Professor Simon New- comb, LL.D., Professor IT. S. Naval Observatory, for some of the most recent information, and for the use of the unequalled engravings of Jupiter, Saturn, and the great nebula of Orion. CONTENTS. CHAP. PAOK I. CREATIVE PROCESSES 1 II. CREATIVE PROGRESS 15 Constitution of Light 24 Chemistry of Suns revealed by Light 28 Creative Force of Light 30 III. ASTRONOMICAL INSTRUMENTS 41 The Telescope 43 The Reflecting Telescope 44 The Spectroscope 46 IV. CELESTIAL MEASUREMENTS 55 Celestial Movements 58 How to Measure 60 V. THE SUN 75 What the Sun does for us 94 VI. THE PLANETS, AS SEEN FROM SPACE 97 The Outlook from the Earth 108 VII. SHOOTING-STARS, METEORS, AND COMETS 117 Aerolites 122 Comets 126 Famous Comets 128 Of what do Comets consist? 131 Will Comets strike the Earth? 133 VIII. THE PLANETS AS INDIVIDUALS 135 Vulcan 138 Mercury 138 Venus 139 The Earth 141 The Aurora Borealis ..143 X CONTENTS. CHAP. PAQ VIII. THE PLANETS AS INDIVIDUALS Continued. The Delicate Balance of Forces 144 Tides 146 The Moon 151 Telescopic Appearance 155 Eclipses 157 Mars 159 Satellites of Mars 161 Asteroids 162 Jupiter 164 Satellites of Jupiter 165 Saturn 167 Rings of Saturn 169 Satellites of Saturn 172 Uranus 173 Neptune 175 IX. THE NEBULAR HYPOTHESIS 179 X. THE STELLAR SYSTEM 193 The Open Page of the Heavens 195 Equatorial Constellations 202 Characteristics of the Stars 209 Number 210 Double and Multiple Stars 210 Colored Stars 214 Clusters of Stars 215 Nebula 217 Variable Stars 220 Temporary, New, and Lost Stars 223 Movements of Stars 226 XL THE WORLDS AND THE WORD 229 XII. THE ULTIMATE FORCE 247 SUMMARY OF LATEST DISCOVERIES AND CONCLUSIONS 268 SOME ELEMENTS OF THE SOLAR SYSTEM 274 EXPLANATION OF ASTRONOMICAL SYMBOLS 275 Signs of the Zodiac 275 Other Abbreviations Used in the Almanac 275 Greek Alphabet Used Indicating the Stare 275 CHAUTAUQUA OUTLINE FOR STUDENTS 276 GLOSSARY OF ASTRONOMICAL TERMS AND INDEX 279 ILLUSTRATIONS. FIG. PAGE The Constellations of Orion and Taurus Frontispiece 1. An Orbit resulting from Attraction and Projection 8 2. The Moon's Orbit about the Earth 10 3. Changes of Orbit by Mutual Attraction 11 4. Velocity of Light measured by Jupiter's Satellites 22 5. Velocity of Light measured by Fizeau's Toothed Wheel 23 6. White Light resolved into Colors 25 7. Showing amount of Light received by Different Planets 37 8. Measuring Intensities of Lights 37 9. Reflection and Diffusion of Light 38 10. Manifold Reflections 39 11. Refraction by Water 40 12. Atmospherical Refraction 40 13. Refracting Telescope 43 14. Reflecting Telescope 44 15. The Cambridge Equatorial Refractor 46 16. The new Reflecting Telescope at Paris 47 17. Spectroscope, with Battery of Prisms 49 18. Spectra of Glowing Hydrogen and of the Sun 50 19. Illustrating Arcs and Angles 59 20. Measuring Objects by observing Angles 59 21. Mural Circle 61 22. Scale to measure Hundredths of an Inch 63 23. Spider-lines to determine Star Transits 65 24. Illustrating Triangulation 66 xii ILLUSTRATIONS. FIG. PAGE 25. Measuring Distance to an Inaccessible Object 67 26. Measuring Elevation of an Inaccessible Object 67 27. Illustrating Parallax 69 28. Illustrating Stellar Parallax 71 29. Mode of Ascertaining Longitude 72 30. Relative Size of Sun, as seen from Different Planets 79 31. Zodiacal Light 80 32. Corona of the Sun in 1858 Brazil 82 33. Corona of the Sun in 1878 Colorado 83 34. Solar Prominences of Flaming Hydrogen 85 35. Changes in Solar Cavities during Rotation 90 36. Solar Spot 92 37. Holding Telescope to see the Sun-spots 96 38. Orbits and Comparative Sizes of the Planets 100 39. Orbit of Earth, illustrating Seasons 103 40. Inclination of Planes of Planetary Orbits 107 41. Inclination of Orbits of Earth and Venus 107 42. Showing the Sun's Movement among the Stars 110 43. Passage of the Sun by Star Regulus Ill 44. Apparent Path of Jupiter among the Stars 112 45. Illustrating Position of Planets 112 46. Apparent Movements of an Inferior Planet 113 47. Apparent Movements of a Superior Planet 114 47a. A Swarm of Meteors meeting the Earth 118 48. Explosion of a Bolide 120 49. Flight of Bolides 121 50. The Santa Rosa Aerolite 122 51. Orbit of November Meteors and the Comet of 1866 125 52. Aspects of Remarkable Comets 127 53. Phases and Apparent Dimensions of Venus 140 54. The Earth and Moon in Space 142 55. Aurora as Waving Curtains 143 56. Tide resulting from Centrifugal Motion 147 57. Lunar Landscape 150 ILL USTRA TIONS. Xlii FIG. PAGE 58. Telescopic View of the Moon 154 59. Illumination of Lunar Craters and Peaks 155 60. Lunar Crater "Copernicus" 156 61. Eclipses: Shadows of Earth and Moon 157 62. Apparent Sizes of Mars, seen from the Earth 160 63. Jupiter 164 64. Various Positions of Jupiter's Satellites 166 65. View of Saturn and his Rings 168 66. Perturbations of Uranus 176 67. Map: Cireumpolar Constellations 201 68. Map of Constellations on the Meridian in December 202 69. Map of Constellations on the Meridian in January 203 70. Map of Constellations on the Meridian in April 204 71. Map of Constellations on the Meridian in June 205 72. Map of Constellations on the Meridian in September 206 73. Map of Constellations on the Meridian in November 207 74. Southern Cireumpolar Constellations 208 75. Aspects of Double Stars 213 76. Sprayed Star Cluster below rj in Hercules 216 77. Globular Star Cluster in the Centaur 216 78. Great Nebula about Orionis 218 79. The Crab Nebula above Tauri 219 80. The Ring Nebula in Lyra 220 81. Showing Place of Ring Nebula 221 82. The Horizontal Pendulum.... ... 272 MAPS TO FIND THE STARS At the End. I. CREATIVE PROCESSES. "In tha beginning God created the heaven and the earth. And the earth was without form, and void ; and darkness was upon the face of the deep." Genesis i. 1, 2. 1 " Not to the domes, where crumbling arch and column Attest tlie feebleness of mortal hand, But to that fane, most catholic and solemn, Which God hath planned, To that cathedral, boundless as our wonder, Whose quenchless lamps the sun and moon supply , Its choir the winds and waves, its organ thunder, Its dome the sky." HORACE SMITH " The heavens are a point from the pen of His perfection ; The world is a rose-bud from the bower of His beauty ; The sun is a spark from the light of His wisdom ; And the sky a bubble on the sea of His power." SIR W. JONES RECREATIONS IN ASTRONOMY. I. CREATIVE PROCESSES. DURING all the ages there has been one bright and glittering page of loftiest wisdom unrolled before the eye of man. That this page may be read in every part, man's whole world turns him before it. This motion apparently changes the eternally stable stars into a mov- ing panorama, but it is only so in appearance. The sky is a vast, immovable dial-plate of " that clock whose pendulum ticks ages instead of seconds," and whose time is eternity. The moon moves among the illumi- nated figures, traversing the dial quickly, like a second- hand, once a month. The sun, like a minute-hand, goes over the dial once a year. Various planets stand for hour-hands, moving over the dial in various periods reaching up to one hundred and sixty-four years ; while the earth, like a ship of exploration, sails the infinite azure, bearing the observers to different points where they may investigate the infinite problems of this mighty machinery. This dial not only shows present movements, but it keeps the history of uncounted ages past ready to be 4 CREATIVE PROCESSES. read backward in proper order ; and it has glorious vol- umes of prophecy, revealing the far-off future to any man who is able to look thereon, break the seals, and read the record. Glowing stars are the alphabet of this lofty page. They combine to form words. Mete- ors, rainbows, auroras, shifting groups of stars, make pictures vast and significant as the armies, angels, and falling stars in the Revelation of St. John changing and progressive pictures of infinite wisdom and power. Men have not yet advanced as far as those who saw the pictures John describes, and hence the panorama is not understood. That continuous speech that day af- ter day uttereth is not heard ; the knowledge that night after night showeth is not seen ; and the invisible things of God from the creation of the world, even his eternal power and Godhead, clearly discoverable from things that are made, are not apprehended. The greatest triumphs of men's minds have been in astronomy and ever must be. We have not learned its alphabet yet. "We read only easy lessons, with as many mistakes as happy guesses. But in time we shall know all the letters, become familiar with the combi- nations, be apt at their interpretation, and will read with facility the lessons of wisdom and power that are written on the earth, blazoned in the skies, and pictured by the flowers below and the rainbows above. In order to know how worlds move and develop, we must create them; we must go back to their begin- ning, give their endowment of forces, and study the laws of their unfolding. This we can easily do by that faculty wherein man is likest his Father, a creative im- agination. God creates and embodies ; we create, but FORCE OF ATTRACT/OX. 5 it remains in thought only. But the creation is as bright, strong, clear, enduring, and real, as if it were em- bodied. Every one of us would make worlds enough to crush us, if we could embody as well as create. Our ambition would outrun our wisdom. Let us come into the high and ecstatic frame of mind which Shakspeare calls frenzy, in the exigencies of his verse, when "The poet's eye, in a fine frenzy rolling, Doth glance from heaven to earth, from earth to heaven ; And, as imagination bodies forth The forms of things unknown, the poet's pen Turns them to shapes, and gives to airy nothing A local habitation and a name." In the supremacy of our creative imagination let us make empty space, in order that we may therein build up a new universe. Let us wave the wand of our pow- er, so that all created things disappear. There is no world under our feet, no radiant clouds, no blazing sun, no silver moon, nor twinkling stars. We look up, there is no light ; down, through immeasurable abysses, there is no form ; all about, and there is no sound or sign of being nothing save utter silence, utter darkness. It cannot be endured. Creation is a necessity of mind even of the Divine mind. We will now, by imagination, create a monster world, every atom of which shall be dowered with the single power of attraction. Every particle shall reach out its friendly hand, and there shall be a drawing to- gether of every particle in existence. The laws gov- erning this attraction shall be two. When these parti- cles are associated together, the attraction shall be in proportion to the mass. A given mass will pull twice 6 CREATIVE PROCESSES. as much as one of half the size, because there is twice as much to pull. And a given mass will be pulled twice as much as one half as large, because there is twice as much to be pulled. A man who weighed one hundred and fifty pounds on the earth might weigh a ton and a half on a body as large as the sun. That shall be one law of attraction ; and the other shall be that masses attract inversely as the square of distances between them. Absence shall affect friendships that have a material basis. If a body like the earth pulls a man one hundred and fifty pounds at the surface, or four thousand miles from the centre, it will pull the same man one -fourth as much at twice the distance, one-sixteenth as much at four times the distance. That is, he will weigh by a spring balance thirty-seven and a half pounds at eight thousand miles from the centre, and nine pounds six ounces at sixteen thousand miles from the centre, and he will weigh or be pulled by the earth T * T of a pound at the distance of the moon. But the moon would be large enough and near enough to pull twenty-four pounds on the same man, so the earth could not draw him away. Thus the two laws of at- traction of gravitation are 1, Gravity is proportioned to the quantity of matter ; and 2, The force of gravity varies inversely as the square of the distance from the centre of the attracting body. The original form of matter is gas. Almost as I write comes the announcement that Mr. Lockyer has proved that all the so-called primary elements of mat- ter are only so many different sized molecules of one original substance hydrogen. Whether that is true or not, let us now create all the hydrogen we can FORCE OF ATTRACTION. 7 imagine, either in differently sized masses or in com- bination with other substances. There it is ! We can- not measure its bulk ; we cannot fly around it in any recordable eons of time. It has boundaries, to be sure, for we are finite, but we cannot measure them. Let it alone, now; leave it to itself. What follows? It is dowered simply with attraction. The vast mass begins to shrink, the outer portions are drawn inward. They rush and swirl in vast cyclones, thousands of miles in extent. The centre grows compact, heat is evolved by impact, as will be explained in Chapter II. Dull red light begins to look like coining dawn. Centuries go by; contraction goes on; light blazes in insufferable brightness ; tornadoes, whirlpools, and tempests scarcely signify anything as applied to such tumultuous tossing. There hangs the only world in existence ; it hangs in empty space. It has no tendency to rise ; none to fall ; none to move at all in any direction. It seethes and flames, and holds itself together by attractive power, and that is all the force with which we have endowed it. Leave it there alone, and withdraw millions of miles into space : it looks smaller and smaller. We lose sight of those distinctive spires of flame, those terrible move- ments. It only gives an even effulgence, a steady un- flickering light. Turn one quarter round. Still we see our world, but it is at one side. Now in front, in the utter darkness, suddenly create another world of the same size, and at the same distance from you. There they stand two huge, lone bodies, in empty space. But we created them dowered with at- traction. Each instantly feels the drawing influence of the other. They are mutually attractive, and begin to 8 CREATIVE PROCESSES. move toward each other. They hasten along an uride- viating straight line. Their speed quickens at every mile. The attraction increases every moment. They fly swift as thought. They dash their flaming, seething foreheads together. And now we have one world again. It is twice as large as before, that is all the difference. There is no variety, neither any motion ; just simple flame, and noth- ing to be warmed thereby. Are our creative powers exhausted by this effort ? No, we will create another world, and add another power to it that shall keep them apart. That power c Fig. 1. Orbit A D, resuUiiig from attraction, A C, aud projectile force, A B. shall be what is called the force of inertia, which is literally no power at all ; it is an inability to originate or change motion. If a body is at rest, inertia is that quality by which it will forever remain so, unless acted upon by some force from without ; and if a body is in motion, it will continue on at the same speed, in a straight line, forever, unless it is quickened, retarded, or turned from its path by some other force. Suppose our newly created sun is 860,000 miles in diameter. Go away 92,500,000 miles and create an earth eight thou- sand miles in diameter. It instantly feels the at- tractive power of the sun drawing it to itself twenty- FORCES OF ATTRACTION AND INERTIA. & four miles the first hour. Now, just as it starts, give this earth a push in a line at right angles with line of fall to the sun, that shall se.id it 66,168 miles every hour thereafter. It obeys both forces. The result is that the world moves constantly forward at the same speed by its inertia from that first push, and attraction momentarily draws it from its straight line, so that the new world circles round the other to the starting-point. Continuing under the operation of both forces, the worlds can never come together or fly apart. They circle about each other as long as these forces endure ; for the first world does not stand still and the second do all the going ; both revolve around the centre of gravity common to both. In case the worlds are equal in mass, they will both take the same orbit around a central stationary point, midway between the two. In case their mass be as one to eighty-one, as in the case of the earth and the moon, the centre of grav- ity around which both turn will be V of the distance from the earth's centre to the moon's centre. This brings the central point around which both worlds swing just inside the surface of the earth. It is like an apple attached by a string, and swung around the hand ; the hand moves a little, the apple very much. Thus the problem of two revolving bodies is readily comprehended. The two bodies lie in easy beds, and swing obedient to constant forces. When another body, however, is introduced, with its varying attraction, first on one and then on the other, complications are intro- duced that only the most masterly minds can follow. Introduce a dozen or a million bodies, and complica- tions arise that only Omniscience can unravel. 1* 10 CREATIVE PROCESSES. Let the hand swing an apple by an elastic cord. When the apple falls toward the earth it feels another force besides that derived from the hand, which greatly lengthens the elastic cord. To tear it away from the earth's attraction, and make it rise, requires additional force, and hence the string is lengthened ; but when it passes over the hand the earth attracts it downward, and the string is very much shortened : so the moon, held by an elastic cord, swings around the earth. From its extreme distance from the earth, at A, Fig. 2, it rushes with increasing speed nearly a quarter of a million of miles toward the sun, feeling its attraction increase with every mile until it reaches B; then it is retarded in its speed, by the same attraction, as it climbs back its quarter of a million of miles away from the sun, in defiance of its pow- er, to C. All the while the invisi- ble elastic force of the earth is nn- weariedly maintained ; and though the moon's dis- tances vary over a range of 31,355 miles, the moon is always in a determinable place. A simple revolu- tion of one world about another in a circular orbit would be a problem of easy solution. It would always be at the same distance from its centre, and going with the same velocity. But there are over sixty causes that interfere with such a simple orbit in the case of the moon, all of which causes and their disturbances must be considered in calculating such a simple matter as an eclipse, or predicting the moon's place as the sailors' guide. One of the most puzzling of the irregularities FORCES OF ATTRACTION AND INERTIA. 11 of our night-wandering orb has just been explained by Professor Hansen, of Gotha, as a curious result of the attraction of Venus. Take a single instance of the perturbations of Jupiter and Saturn which can be rendered evident. The times of orbital revolution of Saturn and Jupiter are nearly as five to two. Suppose the orbits of the planets to be, as in Fig. 3, both ellipses, but not necessarily equally distant in all parts. The planets are as near as possible at 1,1. Drawn toward each oth- er by mutual attraction, Jupi- ter's orbit bends outward, and Fig . 3 ._c^STf orbit i>, Saturn's becomes more nearly mutual attraction, straight, as shown by the dotted lines. A partial cor- rection of this difficulty immediately follows. As Jupi- ter moves on ahead of Saturn it is held back retarded in its orbit by that body ; and Saturn is hastened in its orbit by the attraction of Jupiter. Now greater speed means a straighter orbit. A rifle-ball flies nearer in a straight line than a thrown stone. A greater velocity given to a whirled ball pulls the elastic cord far enough to give the ball a larger orbit. Hence, being hastened, Saturn stretches out nearer its proper orbit, and, retard- ed, Jupiter approaches the smaller curve that is its true orbit. But if they were always to meet at this point, as they would if Jupiter made two revolutions to Saturn's one, it would be disastrous. In reality, when Saturn has gone around two-thirds of its orbit to 2, Jupiter will have gone once and two- thirds around and overtaken 12 CREATIVE PROCESSES. Saturn ; and they will be near again, be drawn togeth er, hastened, and retarded, as before ; their next con- junction would be at 3, 3, etc. Now, if they always made their conjunction at points equally distant, or at thirds of their orbits, it would cause a series of increasing deviations ; for Jupiter would be constantly swelling his orbit at three points, and Saturn increasingly contracting his orbit at the same points. Disaster would be easily foretold. But as their times of orbital revolutions are not exactly in the ratio of five and two, their points of conjunction slowly travel around the orbit, till, in a period of nine hundred years, the starting-point is again reached, and the perturba- tions have mutually corrected one another. For example, the total attractive effect of one planet on the other for 450 years is to quicken its speed. The effect for the next 450 years is to retard. The place of Saturn, when all the retardations have accumulated for 450 years, is one degree behind what it is computed if they are not considered ; and 450 years later it will be one degree before its computed place a perturbation of two degrees. When a bullet is a little heavier or ragged on one side, it will constantly swerve in that di- rection. The spiral groove in the rifle, of one turn in forty-five feet, turns the disturbing weight or raggedness from side to side makes one error correct another, and so the ball flies straight to the bull's-eye. So the place of Jupiter and Saturn, though further complicated by four moons in the case of Jupiter, and eight in the case of Saturn, and also by perturbations caused by other plan- ets, can be calculated with exceeding nicety. The difficulties would be greatly increased if the or- FORCES OF ATTRACTION AND INERTIA. i bits of Satnrn and Jupiter, instead of being 400,000,000 miles apart, were interlaced. Yet there are the or- bits of two hundred and tit'ty asteroids so interlaced that, if they were made of wire, no one could be lifted without raising the whole net-work of them. Never- theless, all these swift chariots of the sky race along the course of their intermingling tracks as securely as if they were each guided by an intelligent mind. They are guided l>y an intelligent mind and an almighty arm. Still more complicated is the question of the mutual attractions of all the planets. Lagrange has been able to show, by a mathematical genius that seems little short of omniscience in his single department of knowledge, that there is a discovered system of oscillations, affect- ing the entire planetary system, the periods of which are immensely long. The number of these oscillations is equal to that of all the planets, arid their periods range from 50,000 to 2,000,000 years. Looking into the open page of the starry heavens we see double stars, the constituent parts of which must re- volve around a centre common to them both, or rush to a common ruin. Eagerly we look to see if they revolve, and beholding them in the very act, we conclude, not groundlessly, that the same great law of gravitation holds good in distant stellar spaces, and that there the same sufficient mind plans, and the same sufficient power directs and controls all movements in harmony and security. When we come to the perturbations caused by the mutual attractions of the sun, nine planets, twenty moons, two hundred and fifty asteroids, millions of 14 CREATIVE PROCESSES. comets, and innumerable meteoric bodies swarming in space, and when we add to all these, that belong to one solar system, the attractions of all the systems of the other suns that sparkle on a brilliant winter night, we are compelled to say, " As high as the heavens are above the earth, so high above our thoughts and ways must be the thoughts and ways of Him who compre- hends and directs them all." II. CREATIVE PROGRESS. "And God said, Let there be light, and there was light." Genesis I., 3. "God is light."! John, i., 6. " Hail ! holy light, offspring of Heaven first born, Or of the eternal, co-eternal beam, May I express thee unblamed ? since God is light. And never but in unapproached light Dwelt from eternity, dwelt then in thee, Bright effluence of bright essence increate." MILTON. " A million torches lighted by Thy hand Wander unwearied throiigh the blue abyss ; They own Thy power, accomplish Thy command, All gay with life, all eloquent with bliss. What shall we call them ? Piles of crystal light A glorious company of golden streams Lamps of celestial ether burning bright Suns lighting systems with their joyous beams i But Thou to these art as the noon to night." DERZHAVIN. trans, by BOWRING, FORCES OF THE SUXBEAM. 17 II. CREATIVE PROGRESS. WORLDS would be very imperfect and useless when simply endowed with attraction and inertia, if no time were allowed for these forces to work out their legiti- mate results. We want something more than swirling eas of attracted gases, something more than compacted rocks. We look for soil, verdure, a paradise of beauty, animal life, and immortal minds. Let us go on with the process. Light is the child of force, and the child, like its fa- ther, is full of power. We dowered our created world with but a single quality a force of attraction. It not only had attraction for its own material substance, but sent out an all-pervasive attraction into space. By the force of condensation it flamed like a sun, and not only lighted its own substance, but it filled all space with the luminous outgoings of its power. A world may be limited, but its influence cannot; its body may have bounds, but its soul is infinite. Everywhere is its mani- festation as real, power as effective, presence as actual, as at the central point. He that studies ponderable bodies alone is not studying the universe, only its skel- eton. Skeletons are somewhat interesting in themselves, hut far more so when covered with flesh, flushed w r ith beauty, and inspired with soul. The universe has bones- 18 CREATIVE PROGRESS. flesh, beauty, soul, and all is one. It can be understood only by a study of all its parts, and by tracing effect to cause. But how can condensation cause light ? Power can- not be quiet. The mighty locomotive trembles with its own energy. A smitten piece of iron has all its infini- tesimal atoms set in vehement commotion ; they surge back and forth among themselves, like the waves of a storm-blown lake. Heat is a mode of motion. A heat- ed body commences a vigorous vibration among its par- ticles, and communicates these vibrations to the sur- rounding air and ether. When these vibrations reach 396,000,000,000,000 per second, the human eye, fitted to be affected by that number, discerns the emitted un- dulations, and the object seems to glow with a dull red light; becoming hotter, the vibrations increase in rapid- ity. When they reach 765,000,000,000,000 per second the color becomes violet, and the eye can observe them no farther. Between these numbers are those of differ- ent rapidities, which affect the eye as orange, yellow, green, blue, indigo, in an almost infinite number of shades according to the sensitiveness of the eye. We now see how our dark immensity of attractive atoms can become luminous. A force of compression results in vibrations within, communicated to the ether, discerned by the eye. Illustrations are numerous. If we suddenly push a piston into a cylinder of brass, the force produces heat enough to set fire to an inflam- mable substance within. Strike a half -inch cube of iron a moderate blow and it becomes warm ; a sufficient blow, and its vibrations become quick enough to be seen it is red-hot. Attach a thermometer to an extended FORCES OF THE SUNBEAM. 19 arm of a whirling wheel ; drive it against the air live hundred feet per second, the mercury rises 16. The earth goes 98,000 feet per second, or one thousand miles a minute. If it come to an aerolite or mass of metallic rock, or even a cloudlet of gas, standing still in space, its contact with our air evolves 600,000 of heat. And when the meteor comes toward the world twenty -six miles a second, the heat would become proportionally greater if the meteor could abide it, and not be con- sumed in fervent heat. It vanishes almost as soon as seen. If there were meteoric masses enough lying in our path, our sky would blaze with myriads of flashes of light. Enough have been seen to enable a person to read by them at night. If a sufficient number were present, we should miss their individual flashes as they blend their separate fires in one sea of insufferable glory. The sun is 326,800 as heavy as our planet; its attraction proportionally greater ; the aerolites more numerous ; and hence an infinite hail of stones, small masses and little worlds, makes ceaseless trails of light, whose individuality is lost in one dazzling sea of glory. On the 1st day of September, 1859, two astronomers, independently of each other, saw a sudden brightening on the surface of the sun. Probably two large meteoric masses were travelling side by side at two or three hun- dred miles per second, and striking the sun's atmos- phere, suddenly blazed into light bright enough to be seen on the intolerable light of the photosphere as a background. The earth responded to this new cause of brilliance and heat in the sun. Vivid auroras ap- peared, not only at the north and south poles, but even where such spectacles are seldom seen. The electro- 20 CREATIVE PROGRESS. magnetic disturbances were more distinctly marked. " In many places the telegraphic wires struck work. In Washington and Philadelphia the electric signalmen re- ceived severe electric shocks ; at a station in Norway the telegraphic apparatus was set fire to ; and at Boston a flame of tire followed the pen of Bain's electric tele- graph." There is the best of reason for believing that a continuous succession of such bodies might have gone far toward rendering the earth uncomfortable as a place of residence. Of course, the same result of heat and light would follow from compression, if a body had the power of contraction in itself. We endowed every particle of our gas, myriads of miles in extent, with an attraction for every other particle. It immediately compressed itself into a light-giving body, which flamed out through the interstellar spaces, flushing all the celestial regions with exuberant light. But heat exerts a repellent force among particles, and soon an equilibrium is reached, for there comes a time when the contracting body can contract no farther. But heat and light radiate away into cold space, then contrac- tion goes on evolving more light, and so the suns flame on through the millions of years unquenched. It is es- timated that the contraction of our sun, from filling im- mensity of space to its present size, could not afford heat enough to last more than 18,000,000 years, and that its contraction from its present density (that of a swamp) to such rock as that of which our earth is composed, could supply heat enough for 17,000,000 years longer. But the far-seeing mind of man knows a time must come when the present force of attraction FORCES OF ^HE SUNBEAM. 21 shall have produced all the heat it can, and a new force of attraction must be added, or the sun itself will be- come cold as a cinder, dead as a burned-out char. Since light and heat are the product of such enor- mous cosmic forces, they must partake of their nature, and be force. So they are. The sun has long arms, and they are full of unconquerable strength ninety-two millions, or any other number of millions, of miles away. All this light and heat comes through space that is 200 below zero, through utter darkness, and ap- pears only on the earth. So the gas is darkness in the underground pipes, but light at the burner. So the electric power is unfelt by the cable in the bosom of the deep, but is expressive of thought and feeling at the end. Having found the cause of light, we will com- mence a study of its qualities and powers. Light is the astronomer's necessity. When the sub- lime word was uttered, " Let there be light !" the study of astronomy was made possible. Man can gather but little of it with his eye ; so he takes a lens twenty-six inches in diameter, and bends all the light that passes through it to a focus, then magnih'es the image and takes it into his eye. Or he takes a mirror, six feet in diameter, so hollowed in the middle as to reflect all the rays falling upon it to one point, and makes this larger eye fill his own with light. By this Isrger light-gath- ering he discerns things for which the light falling on his pupil one-fifth of an inch in diameter would not be sufficient. We never have seen any sun or stars ; we have only seen the light that left thorn a few min- utes or years ago, more or less. Light is the aerial sprite that carries our measuring-rods across the infinite 22 CREATIVE PROGRESS. spaces ; light spreads out the history of that far-off be- ginning ; brings us the measure of stars a thousand times brighter than our sun ; takes up into itself evidences of the very constitutional elements of the far-off suns, and spreads them at our feet. It is of such capacity that the Divine nature, looking for an expression of its own omnipotence, omniscience, and power of revelation, was content to say, " God is Light." We shall need all our delicacy of analysis and measurement when we seek to determine the activities of matter so tine and near to spirit as light. "We first seek the velocity of light. In Fig. 4 the earth is 92,500,000 miles from the sun at E; Jupiter is 480,000,000 miles from the sun at J. It has four Fig. 4. Velocity of Light measured by Eclipses of Jupiter's Moons. moons : the inner one goes around the central body in forty-two hours, and is eclipsed at every revolution. The light that went out from the sun to M ceases to be reflected back to the earth by the intervention of the plan- et Jupiter. We know to a second when these eclipses take place, and they can be seen with a small telescope. But when the earth is on the opposite side of the sun FORCES OF THE SUNBEAM. 23 from Jupiter, at E', these eclipses at J' take place sixteen and a half minutes too late. What is the reason ? Is the celestial chronometry getting deranged ? No, indeed ; these great worlds swing never an inch out of place, nor a second out of time. By going to the other side of the sun the earth is 185,000,000 miles farther from Jupiter, and the light that brings the intelligence of that eclipse consumes the extra time in going over the extra distance. Divide one by the other and we get the velocity, 186,868 miles per second. That is probably correct to within a thousand miles. Methods of measurement by the toothed wheel of Fizeau confirm this re- sult. Suppose the wheel, Fig. 5, to have one thou- sand teeth, making five revolutions to the second. Five thousand flashes of Pig . 5. -Measuring the Velocity of Light. light each second will dart out. Let each flash travel nine miles to a mirror and return. If it goes that distance in Io ^ 07 of a sec- ond, or at the rate of 180,000 miles a second, the next tooth will have arrived before the eye, and each return- ing ray be cut off. Hasten the revolutions a little, and the next notch will then admit the ray, on its return, that went out of each previous notch : the eighteen miles hav- ing been traversed meanwhile. The result of experi- ments by Lieut. Michelson, as given Sept., 1879, is 186,380 miles per second, which cannot be fifty miles from correct. When we take instantaneous photographs by the ex- 24 CREATIVE PROGRESS. posure of the sensitive plate 2o ooo P H1 't f a second, a stream of light nine miles long dashes in upon the plate in that very brief period of time. The highest velocity we can give a rifle-ball is 2000 feet a second, the next second it is only 1500 feet, and oon it comes to rest. We cannot compact force enough behind a bit of lead to keep it flying. But light flies unweariedly and without diminution of speed. When it has come from the sun in eight minutes, Alpha Cen- tauri in three years, Polaris in forty -five years, other stars in one thousand, its wings are in nowise fatigued, nor is the rapidity of its flight slackened in the least. It is not the transactions of to-day that we read in the heavens, but it is history, some of it older than the time of Adam. Those stars may have been smitten out of existence decades of centuries ago, but their poured- out light is yet flooding the heavens. It can go both ways at once in the same place, without interference. We see the light reflected from the new moon to the earth ; reflected back from the house-tops, fields, and waters of earth, to the moon again, and from the moon to us once more three times in opposite di- rections, in the same place, without interference, and thus we see " the old moon in the arms of the new." Constitution of Light. Light was once supposed to be corpuscular, or con- sisting of transmitted particles. It is now known to be the result of undulations in ether. Reference has been made to the minuteness of these undulations. Their velocity is equally wonderful. Put a prism of glass into a ray of light coming into a dark room, and it is FORCES OF THE SUNBEAM. 25 instantly turned out of its course, some parts more and some less, according to the number of vibrations, and ap- pears as the seven colors on different parts of the screen. Fig. 6 shows the arrangement of colors, and the number of millions of millions of vibrations per second of each. Pig. 6 White Light resolved into Colors. But the different divisions we call colors are not colors in themselves at all, but simply a different number of vibrations. Color is all in the eye. Violet has in dif- ferent places from 716 to 765,000,000,000,000 of vibra- tions per second ; red has, in different places, from 396 to 470,000,000,000,000 vibrations per second. None of these in any sense are color, but affect the eye different- ly, and we call these different effects color. They are simply various velocities of vibration. An object, like one kind of stripe in our flag, which absorbs all kinds of vibrations except those between 396 and 470,000,000,- 000,000, and reflects those, appears red to us. The field for the stars absorbs and destroys all but those vibra- tions numbering about 653,000,000,000,000 of vibra- 2 26 CREATIVE PROGRESS. tions per second. A color is a constant creation. Light makes momentary color in the flag. Drake might have written, in the continuous present as well as in the past, " Freedom mingles with its gorgeous dyes The milky baldrick of the skies, And stripes its pure celestial white With streakings of the morning light." Every little pansy, tender as fancy, pearled with eva- nescent dew, fresh as a new creation of sunbeams, has power to suppress in one part of its petals all vibrations we call red, in another those we call yellow, and pur- ple, and reflect each of these in other parts of the same tender petal. "Pansies are for thoughts," even more thoughts than poor Ophelia knew. A cloud of smoke that is dense enough to absorb all the faster and weaker vibrations, leaving only the stronger to come through, will show the sun as red ; because the vibrations that produce the impression we have so named are the only ones that have vigor enough to get through. It is like an army charging upon a fortress. Under the deadly fire and fearful obstructions six-sevenths go down, but one-seventh comes through with the glory of victory upon its face. Light comes in undulations to the eye, as tones of sound to the ear. Must not light also sing? The lowest tone we can hear is made by 16.5 vibrations of air per second ; the highest, so shrill and "fine that nothing lives 'twixt it and silence," is made by 38,000 vibrations per second. Between these extremes lie eleven octaves ; C of the G clef having 258 vibrations to the second, and its octave above 517. Not that sound vibrations cease FORCES OF THE SUNBEAM. 27 at 38,000, but our organs are not fitted to hear beyond those limitations. If our ears were delicate enough, we could hear even up to the almost infinite vibrations of light. In one of those semi -inspirations we find in Shakspeare's works, he says "There's not the smallest oib which thou beholdest, But in his motion like an angel sings, Still quiring to the young-eyed cherubim. Such harmony is in immortal souls ; But, whilst this muddy vesture of decay Doth grossly close it in, we cannot hear it." And that older poetry which is always highest truth says, "The morning stars sing together." We miscon- strued another passage which we could not understand, and did not dare translate as it was written, till science crept up to a perception of the truth that had been stand- ing there for ages, waiting a mind that could take it in. Now we read as it is written " Thou makest the out-goings of the morning and evening to sing." Were our senses fine enough, we could hear the separate key- note of every individual star. Stars differ in glory and in power, and so in the volume and pitch of their song. Were our hearing sensitive enough, we could hear not only the separate key-notes but the infinite swelling harmony of these myriad stars of the sky, as they pour their mighty tide of united anthems in the ear of God : " In reason's ear they all rejoice, And utter forth a glorious voice. Forever singing, as they shine, The hand that made us is divine." This music is not monotonous. Stars draw near each other, and make a light that is unapproachable by mor- 28 CREATIVE PROGRESS. tals; then the music swells beyond our ability to en- dure. They recede far away, making a light so dim that the music dies away, so near to silence that only spirits can perceive it. No wonder God rejoices in his works. They pour into his ear one ceaseless tide of rapturous song. Our senses are limited we have only five, but there is room for many more. Some time we shall be taken out of " this muddy vesture of decay," no longer see the universe through crevices of our prison-house, but shall range through wider fields, explore deeper mys- teries, and discover new worlds, hints of which have never yet been blown across the wide Atlantic that rolls between them and men abiding in the flesh. Chemistry of Suns revealed J>y Light. When we examine the assemblage of colors spread from the white ray of sunlight, we do not find red sim- ple red, yellow yellow, etc., but there is a vast number of fine microscopic lines of various lengths, parallel here near together, there far apart, always the same number and the same relative distance, when the same light and prism are used. What new alphabets to new realms of knowledge are these ! Remember, that what we call colors are only various n umbel's of vibrations of ether. Remember, that every little group in the infinite variety of these vibrations may be affected differently from every other group. One number of these is bent by the prism to where we see what we call the violet, another number to the place we call red. All of the vibrations are destroyed when they strike a surface we call black. A part of them are destroyed when they FORCES OF THE SUNBEAM. 29 strike a substance we call colored. The rest are reflect- ed, and give the impression of color. In one place on the flag of our nation all vibrations are destroyed ex- cept the red; in another, all but the blue. Perhaps on that other gorgeous flag, not of our country but of our sun, the flag we call the solar spectrum, all vibrations are destroyed where these dark lines appear. Perhaps this effect is not produced by the surface upon which the rays fall, but by some specific substance in the sun. This is just the truth. Light passing through vapor of sodium has the vibrations that would fall on two nar- row lines in the yellow utterly destroyed, leaving two black spaces. Light passing through vapor of burning iron has some four hundred numbers or kinds of vibra- tions destroyed, leaving that number of black lines ; but if the salt or iron be glowing gas, in the source of the light itself the same lines are bright instead of dark. Thus we have brought to our doors a readable rec- ord of the very substances composing every world hot enough to shine by its own light. Thus, while our flag means all we have of liberty, free as the winds that kiss . it, and bright as the stars that shine in it, the flag of the sun means all that it is in constituent elements, all that it is in condition. We find in our sun many substances known to exist in the earth, and some that we had not discovered when the sun wrote their names, or rather made their mark, in the spectrum. Thus, also, we find that Betelguese and Algol are without any perceivable indications of hydrogen, and Sirius has it in abundance. What a sense of acquaintanceship it gives us to look up and recognize 30 CREATIVE PROGRESS. the stars whose very substance we know ! If we were transported thither, or beyond, we should not be alto- gether strangers in an unknown realm. But the stars differ in their constituent elements; every ray that flashes from them bears in its very be- ing proofs of what they are. Hence the eye of Omni- science, seeing a ray of light anywhere in the universe, though gone from its source a thousand years, would be able to tell from what orb it originally came. Creative Force of Light. Just above the color vibrations of the unbraided sun- beam, above the violet, which is the highest number our eyes can detect, is a chemical force ; it works the changes on the glass plate in photography ; it transfig- ures the dark, cold soil into woody fibre, green leaf, downy rose petals, luscious fruit, and far pervasive odor ; it flushes the wide acres of the prairie with grass and flowers, fills the valleys with trees, and covers the hills with corn, a single blade of which all the power of man could not make. This power is also fit and able to survive. The en- gineer Stephenson once asked Dr. Buckland, " What is the power that drives that train?" pointing to one thundering by. " Well, I suppose it is one of your big engines." " But what drives the engine ?" " Oh, very likely a canny Newcastle driver." " No, sir," said the engineer, " it is sunshine." The doctor was too dull to take it in. Let us see if we can trace such an evident effect to that distant cause. Ages ago the warm sun- shine, falling on the scarcely lifted hills of Pennsylvania, caused the reedy vegetation to grow along the banks of FORCES OF THE SUNBEAM. 31 shallow seas, accumulated vast amounts of this vegeta- tion, sunk it beneath the sea, roofed it over with sand, compacted the sand into rock, and changed this vegeta- ble matter the products of the sunshine into coal; and when it was ready, lifted it once more, all garnered for the use of men, roofed over with mighty mountains. We mine the coal, bring out the heat, raise the steam, drive the train, so that in the ultimate analyses it is sun- shine that drives the train. These great beds of coal are nothing but condensed sunshine the sun's great force, through ages gone, preserved for our use to-day. And it is so full of force that a piece of coal that will weigh three pounds (as big as a large pair of fists) has as much power in it as the average man puts into a day's work. Three tons of coal will pump as much water or shovel as much sand as the average man will pump or shovel in a lifetime ; so that if a man proposes to do nothing but work with his muscles, he had better dig three tons of coal and set that to do his work and then die, be- cause his work will be better done, and without any cost for the maintenance of the doer. Come down below the color vibrations, and we shall find that those which are too infrequent to be visible, manifest as heat. Naturally there will be as many dif- ferent kinds of heat as tints of color, because there is as great a range of numbers of vibration. It is our priv- ilege to sift them apart and sort them over, and find what kinds are best adapted to our various uses. Take an electric lamp, giving a strong beam of light and heat, and with a plano-convex lens gather it into a single beam and direct it upon a thermometer, twenty feet away, that is made of glass and filled with air. The 32 CREATIVE PROGRESS. expansion or contraction of this air will indicate the varying amounts of heat. Watch your air-thermometer, on which the beam of heat is pouring, for the result. There is none. And yet there is a strong current of heat there. Put another kind of test of heat beyond it and it appears ; coat the air-thermometer with a bit of black cloth, and that will absorb heat and reveal it. But why not at first? Because the glass lens stops all the heat that can affect glass. The twenty feet of air absorbs all the heat that affects air, and no kind of heat is left to affect an instrument made of glass and air ; but there are kinds of heat enough to affect instruments made of other things. A very strong current of heat may be sent right through the heart of a block of ice without melting the ice at all or cooling off the heat in the least. It is done in this way : Send the beam of heat through water in a glass trough, and this absorbs all the heat that can affect water or ice, getting itself hot, and leaving all other kinds of heat to go through the ice beyond ; and appropriate tests show that as much heat comes out on the other side as goes in on this side, and it does not melt the ice at all. Gunpowder may be exploded by heat sent through ice. Dr. Kane, years ago, made this experiment. He was coming down from the north, and fell in with some Esquimaux, whom he was anx- ious to conciliate. He said to the old wizard of the tribe, " I am a wizard ; I can bring the sun down out of the heavens with a piece of ice." That was a good deal to say in a country where there was so little sun. " So," he writes, " I took my hatchet, chipped a small piece of ice into the form of a double -convex lens, FORCES OF THE SUNBEAM. 33 smoothed it with my warm hands, held it up to the sun, and, as the old man was blind, I kindly burned a blister on the back of his hand to show him I could do it." These are simple illustrations of the various kinds of heat. The best furnace or stove ever invented con- sumes fifteen times as much fuel to produce a given amount of heat as the furnace in our bodies consumes to produce a similar amount. We lay in our supplies of carbon at the breakfast, dinner, and supper table, and keep ourselves warm by economically burning it with the oxygen we breathe. Heat associated with light has very different quali- ties from that which is not. Sunlight melts ice in the middle, bottom, and top at once. Ice in the spring-time is honey-combed throughout. A piece of ice set in the summer sunshine crumbles into separate crystals. Dark heat only melts the surface. Nearly all the heat of the sun passes through glass without hinderance ; but take heat from white-hot plat- inum and only seventy-six per cent, of it goes through glass, twenty -four per cent, being so constituted that it cannot pass with facility. Of heat from copper at 752 only six per cent, can go through glass, the other ninety-four per cent, being absorbed by it. The heat of the sunbeam goes through glass without any hinderance whatever. It streams into the room as freely as if there were no glass there. But what if the furnace or stove heat went through glass with equal facility ? We might as well try to heat our rooms with the window-panes all out, and the blast of winter sweep- ing through them. The heat of the sun, by its intense vibrations, comes 2* 34 CREATIVE PROGRESS. to the earth dowered with a power which pierces the miles of our atmosphere, but if our air were as pervious to the heat of the earth, this heat would fly away every night, and our temperature would go down to 200 be- low zero. This heat comes with the light, and then, dissociated from it, the number of its vibrations lessen- ed, it is robbed of its power to get away, and remains to work its beneficent ends for our good. Worlds that are so distant as to receive only ffaq of the heat we enjoy, riiay have atmospheres that retain it all. Indeed it is probable that Mars, that receives but one-quarter as much heat as the earth, has a tempera- ture as high as ours. The poet drew on his imagination when he wrote : " Who there inhabit must have other powers, Juices, and veins, and sense and life than ours ; One moment's cold like theirs would pierce the bone, Freeze the heart's-blood, and turn us all to stone." The power that journeys along the celestial spaces in the flashing sunshine is beyond our comprehension. It accomplishes with ease what man strives in vain to do with all his strength. At West Point there are some links of a chain that was stretched across the river to prevent British ships from ascending ; these links were made of two-and-a-quarter-inch iron. A powerful loco- motive might tug in vain at one of them and not stretch it the thousandth part of an inch. But the heat of a single gas-burner, that glows with the preserved sun- light of other ages, when suitably applied to the link, stretches it with ease ; such enormous power has a little heat. There is a certain iron bridge across the Thames at London, resting on arches. The warm sunshine, act- FORCES OF THE SUNBEAM. 35 ing upon the iron, stations its particles farther and far- ther apart. Since the bottom cannot give way the arches must rise in the middle. As they become long- er they lift the whole bridge, and all the thundering locomotives and miles of goods-trains cannot bring that bridge down again until the power of the sunshine has been withdrawn. There is Bunker Hill Monument, thirty-two feet square at the base, with an elevation of two hundred and twenty feet. The sunshine of every summer's day takes hold of that mighty pile of granite with its aerial fingers, lengthens the side affected, and bends the whole great mass as easily as one would bend a whipstock. A few years ago we hung a plummet from the top of this monument to the bottom. At 9 A.M. it began to move toward the west ; at noon it swung round toward the north ; in the afternoon it went east of where it first was, and in the night it settled back to its original place. The sunshine says to the sea, held in the grasp of gravitation, " Rise from your bed ! Let millions of tons of water fly on the wings of the viewless air, hundreds of miles to the distant mountains, and pour there those millions of tons that shall refresh a whole continent, and shall gather in rivers fitted to bear the commerce and the navies of nations." Gravitation says, " I will hold every particle of this ocean as near the centre of the earth as I can." Sunshine speaks with its word of power, and says, " Up and away !" And in the wreath- ing mists of morning these myriads of tons rise in the air, fly away hundreds of miles, and supply all the Ni- agaras, Mississippis and Amazons of earth. The sun says to the earth, wrapped in the mantle of winter, 36 CREATIVE PROGRESS. "Bloom again;" and the snows melt, the ice retires, aud vegetation breaks forth, birds sing, and spring is about us. Tims it is evident that every force is constitutional- ly arranged to be overcome by a higher, and all by the highest. Gravitation of earth naturally and legitimate- ly yields to the power of the sun's heat, and then the waters fly into the clouds. It as naturally and legiti- mately yields to the power of mind, and the waters of the Red Sea are divided and stand " upright as an heap." Water naturally bursts into flame when a bit of potas- sium is thrown into it, and as naturally when Elijah calls the right kind of fire from above. What seems a miracle, and in contravention of law, is only the con- stitutional exercise of higher force over forces organ- ized to be swayed. If law were perfectly rigid, there could be but one force ; but many grades exist from cohesion to mind and spirit. The highest forces are meant to have victory, and thus give the highest order and perfectness. Across the astronomic spaces reach all these powers, making creation a perpetual process rather than a single act. It almost seems as if light, in its varied capacities, were the embodiment of God's creative power ; as if, having said, " Let there be light," he need do nothing else, but allow it to carry forward the creative processes to the end of time. It was Newton, one of the earliest and most acute investigators in this study of light, who said, " I seem to have wandered on the shore of Truth's great ocean, and to have gathered a few pebbles more beautiful than common ; but the vast ocean itself rolls before me undiscovered and unexplored." EXPERIMENTS. EXPERIMENTS WITH LIGHT. A light set in a room is seen from every place ; hence light streams in every possible direction. If put in the centre of a hollow sphere, every point of the surface will be equally illumined. If put in a sphere of twice the diameter, the same light will fall on all the larger surface. The surfaces of spheres are as the squares of their diameters ; hence, in the larger sphere the surface is illumined only one-quarter as much as the smaller. The same is true of large and small rooms. In Fig. 7 it is ap- Fig. 7. parent that the light that falls on the first square is spread, at twice the distance, over the second square, which is four times as large, and at three times the distance over nine times the surface. The varying amount of light received by each planet is also shown in fractions above each world, the amount received by the earth being 1. Fig. 8. Measuring Intensities of Lights. The intensity of light is easily measured. Let two lights of different brightness, as in Fig. 8, cast shadows on the same screen. Arrange them as to distance so that both shadows shall be equally dark. Let them fall side by side, and study them carefully. Measure the respective distances. Suppose one is twenty inches, the other forty. Light varies as the square 38 CREATIVE PROGRESS. of the distance : the square of 20 is 400, of 40 is 1600. Divide 1600 by 400, and the result is that one light is four times as bright as the other. Light can be handled, directed, and bent, as well as iron bars. Darken a room and admit a beam of sunlight through a shutter, or a ray of lamp- light through the key-hole. If there is dust in the room it will be observed that light goes in straight lines. Because of this men are able to arrange houses and trees in rows, the hunter aims his rifle correctly, and the as- tronomer projects straight lines to infinity. Take a hand-mirror, or bet- Fig. 9. -Reflection and Diffusion of Light. ter, a piece of glass coated on one side with black varnish, and you can send your ray anywhere. By using two mirrors, or having an assistant and using several, you can cause a ray of light to turn as many corners as you please. I once saw Mr. Tyndall send a ray into a glass jar filled with smoke (Fig. 9). Admitting a slender ray through a small hole in a card over the mouth, one ray appeared ; removing the cover, the whole jar was luminous ; as the smoke disappeared in spots cavities of dark- ness appeared. Turn the same ray into a tumbler of water, it becomes EXPERIMENTS. 39 faintly visible ; stir into it a teaspoonful of milk, then turn in the ray of sunlight, and it glows like a lamp, illuminating the whole room. These experiments show how the straight rays of the sun are diffused in every direction over the earth. Set a small light near one edge of a mirror; then, by putting the eye near the opposite edge, you see almost as many flames as you please from the multiplied reflections. How can this be accounted for ? Into your beam of sunlight, admitted through a half-inch hole, put the mirror at an oblique angle ; you can arrange it so as to throw half a dozen bright spots on the opposite wall. In Fig. 10 the sunbeam enters at A, and, striking the mirror m at a, is partly reflected to 1 on the wall, and partly enters the glass, passes Fig. 10. Manifold Reflections. through to the silvered back at B, and is totally reflected to b, where it again divides, some of it going to the wall at 2, and the rest, continuing to make the same reflections and divisions, causes spots 3, 4, 5, etc. The brightest spot is at No. 2, because the silvered glass at B is the best re- flector and has the most light. When the discovery of the moons of Mars was announced in 1877, it was also widely published that they could be seen by a mirror. Of course this is impossible. The point of light mistaken for the moon in this sec- ondary reflection was caused by holding the mirror in an oblique position. Take a small piece of mirror, say an inch in surface, and putting under it three little pellets of wax, putty, or clay, set it on the wrist, with one of the pellets on the pulse. Hold the mirror steadily in the beam of light, and the frequency and prominence of each pulse-beat will be indicated by the tossing spot of light on the wall. If the operator becomes excited the fact will be evident to all observers. Pla'ce a coin in a basin (Fig. 11), and set it so that the rim will con- ceal the coin from the eye. Pour in water, and the coin will appear 40 CREATIVE PROGRESS. to rise into sight. When light passes from a medium of one density to a medium of another, its direction is changed. Thus a stick in water seems bent. Ships below the horizon are sometimes seen above, because of the different density of the layers of air. Thus light coming from the interstellar spaces, and entering our atmos- phere, is bent down more and more by its increasing density. The effect is greatest when the sun or star is near the horizon, none at all in the zenith. This brings the object into view before it is risen. Allowance for this displacement is made in all delicate astronomical observations. Pig. 12. Atmospherical Refraction. Notice on the floor the shadow of the window-frames. The glass of almost every window is so bent as to turn the sunlight aside enough to obliterate some of the shadows or increase their thickness. DECOMPOSITION OP LIGHT. Admit the sunbeam through a slit one inch long and one-twentieth of an inch wide. Pass it through a prism. Either purchase one or make it of three plain pieces of glass one and a half inch wide by six inches long, fastened together in triangular shape fasten the edges with hot wax and fill it with water ; then on a screen or wall you will have the colors of the rainbow, not merely seven but seventy, if your eyes are sharp enough. Take a bit of red paper that matches the red color of the spectrum. Move it along the line of colors toward the violet. In the orange it is dark, in the yellow darker, in the green and all beyond, black. That is because there are no more red rays to be reflected by it. So a green ob- ject is true to its color only in the green rays, and black elsewhere. All these colors may be recombined by a second prism into white light. III. ASTRONOMICAL INSTRUMENTS. "The eyes of the Lord are in every place." Proverbs xv. 3 "Man, having one kind of an eye given him by his Maker, proceeds to construct two other kinds. He makes one that magnifies invisible objects thousands of times, so that a dull razor-edge appears as thick as three fingers, until the amazing beauty of color and form in infinitesimal ob- jects is entrancingly apparent, and he knows that God's care of least things is infinite. Then he makes the other kind four or six feet in di- ameter, and penetrates the immensities of space thousands of times be- yond where his natural eye can pierce, until he sees that God s immensi- ties of worlds are infinite also." BISHOP FOSTER. THE TELESCOPE. 43 III. THE TELESCOPE. FREQUENT allusion has been made in the previous chapter to discovered results. It is necessary to under- stand more clearly the process by which such results have been obtained. Some astronomical instruments are of the simplest character, some most delicate and complex. When a man smokes a piece of glass, in or- der to see an eclipse of the sun, he makes a simple instrument. Ferguson, lying on his back and slipping beads on a string at a certain distance above his eye, measured the relative distances of the stars. The use of more complex instruments commenced when Galileo applied the telescope to the heavens. He cannot be said to have invented the telescope, but he certainly con- structed his own without a pattern, and used it to good purpose. It consists of a lens, O B (Fig. 13), which Fig. 13. Refracting Telescope. acts as a multiple prism to bend all the rays to one point at R. Place the e} 7 e there, and it receives as much light as if it were as large as the lens O B. The rays, however, are convergent, and the point difficult to 44 ASTRONOMICAL INSTRUMENTS. find. Hence there is placed at K a concave lens, pass- ing through which the rays emerge in parallel lines, and are received by the eye. Opera-glasses are made upon precisely this principle to-day, because they can be made conveniently short. If, instead of a concave lens at K, converting the con- verging rays into parallel ones, we place a convex or magnifying lens, the minute image is enlarged as much as an object seems diminished when the telescope is reversed. This is the grand principle of the refracting telescope. Difficulties innumerable arise as we attempt to enlarge the instruments. These have been overcome, one after another, until we have now Struve's admirable glass of 30 inches, and an assurance of the speedy com- pletion of the 36-inch lens for the Lick Observatory. The Reflecting Telescope. This is the only kind of instrument differing radi- cally from the refracting one already described. It re- ceives the light in a concave mirror, M (Fig. 14), which Fig. 14 Reflecting Telescope. reflects it to the focus F, producing the same result as the lens of the refracting telescope. At B a mirror may be placed obliquely, reflecting the image at right angles to the eye, outside the tube, in which case it is called the Newtonian telescope ; or a mirror at E may be placed perpendicularly, and send the rays through THE REFLECTING TELESCOPE. 45 an opening in the mirror at M. This form is called the Gregorian telescope. Or the mirror M may be slightly inclined to the coming rays, so as to bring the point F entirel-y outside the tube, in which case it is called the Herschelian telescope. In either case the image may be magnified, as in the refracting telescope. Keflecting telescopes are made of all sizes, up to the Cyclopean eye of the one constructed by Lord Rosse, which is six feet in diameter. The form of instru- ment to be preferred depends on the use to which it is to be put. The loss of light in passing through glass lenses is about two -tenths. The loss by reflection is often one-half. In view of this peculiarity and many others, it is held that a twenty-six-inch refractor is fully equal to any six-foot reflector. The mounting of large telescopes demands the high- est engineering ability. The whole instrument, with its vast weight of a twenty-six-irich glass lens, with its accompanying tube and appurtenances, must be pointed as nicely as a rifle, and held as steadily as the axis of the globe. To give it the required steadiness, the foun- dation on which it is placed is sunk deep in the earth, far from rail or other roads, and no part of the observ- atory is allowed to touch this support. When a star is once found, the earth swiftly rotates the telescope away from it, and it passes out of the field. To avoid this, clock-work is so arranged that the great telescope fol- lows the star by the hour, if required. It will take a star at its eastern rising, and hold it constantly in view while it climbs to the meridian and sinks in the west (Fig. 15). The reflector demands still more difficult en- gineering. That of Lord Rosse has a metallic mirror 46 ASTRONOMICAL INSTRUMENTS. weighing six tons, a tube fifty-six feet long, which, with its appurtenances, weighs seven tons more. It moves between two walls only 20 east and west. The new Paris reflector (Fig. 16) has a much wider range of movement. The Spectroscope. A spectrum is a collection of the colors which are dispersed by a prism from any given light. If it is sun- light, it is a solar spectrum ; if the source of light is a Fig. 16. New Paris Reflector. THE SPECTROSCOPE. 49 star, candle, glowing metal, or gas, it is the spectrum of a star, candle, glowing metal, or gas. An instrument to see these spectra is called a spectroscope. Consider- ing the infinite variety of light, and its easy modifica- tion and absorption, we should expect an immense number of spectra. A mere prism disperses the light so imperfectly that different orders of vibrations, per- ceived as colors, are mingled. No eye can tell where one commences or ends. Such a spectrum is said to be impure. What we want is that each point in the spectrum should be made of rays of the same number of vibrations. As we can let only a small beam of light pass through the prism, in studying celestial objects with a telescope and spectroscope we must, in every instance, contract the aperture of the instrument un- til we get only a small beam of light. In or- der to have the colors thoroughly dispersed, the best instruments pass the beam of light through a series of prisms called a bat- tery, each one spread- ing farther the colors which the previous ones had spread. In Fig. 17 the ray is seen 3 . , , , Fig. 17. Spectroscope, with Battery of Prisms. entering through the telescope A, which renders the rays parallel, and pass- ing through the prisms out to telescope B, where the 3 50 ASTRONOMICAL INSTRUMENTS. spectrum can be examined on the retina of the eye for a screen. In order to still farther disperse the rays, some batteries receive the ray from the last prism at upon an oblique mirror, send it up a little to another, which delivers it again to the prism to make its journey back again through them all, and come out to be ex- amined just above where it entered the first prism. Attached to the examining telescope is a diamond- ruled scale of glass, enabling us to fix the position of any line with great exactness. In Fig. 18 is seen, in the lower part, a spectrum of the sun, with about a score of its thousands of lines H ft G FC&K DCBA Fig. IS. Spectra of glowing Hydrogen and the Sun. made evident. In the upper part is seen the spectrum of bright lines given by glowing hydrogen gas. These lines are given by no other known gas; they are its autograph. It is readily observed that they precisely correspond with certain dark lines in the solar spec- trum. Hence we easily know that a glowing gas gives the same bright lines that it absorbs from the light of another source passing through it that is, glowing gas gives out the same rays of light that it absorbs when it is not glowing. We are sure, therefore, that hydrogen exists in the sun. In the same manner we detect salt, iron, and a dozen other metals. Applied to the stars the spectro- THE SPECTROSCOPE. 51 scope shows that they resemble the sun in constitution and general condition. They are divided into four gen- eral orders, according to resemblances of their spectra. The first order includes mostly stars showing a white light, as Rigel, Altair, Regulus, etc. Nearly one-half of the stars are included in this order. The second order includes mostly stars showing a yellow light, as A retu- rns, Aldebaran, etc. These most resemble the sun in condition and chemical condition. The third order shows a red light. The fourth includes only faint stars. A patient study of these signs of substances reveals richer results than a study of the cuniform characters engraved on Assyrian slabs; for one is the handwri- ting of men, the other the handwriting of "God. One of the most difficult and delicate problems solved by the spectroscope is the approach or departure of a light-giving body in the line of sight. Stand before a locomotive a mile away, you cannot tell whether it ap- proaches or recedes, yet it will dash by in a minute. How can the movements of the stars be comprehended when they are at such an immeasurable distance ? It can best be illustrated by music. The note C of the G clef is made by two hundred and fifty-seven vi- brations of air per second. Twice as many vibrations per second would give us the note C an octave above. Sound travels at the rate of three hundred and sixty- four yards per second. If the source of these two hun- dred and fifty -seven vibrations could approach us at three hundred and sixty-four yards per second, it is ob- vious that twice as many waves would be put into a given space, and we should hear the upper C when only waves enough were made for the lower C. The same 52 ASTRONOMICAL INSTRUMENTS. result would appear if we carried our ear toward the sound fast enough to take up twice as many waves as though we stood still. This is apparent to every ob- server in a railway train. The whistle of an approach- ing locomotive gives one tone ; it passes, and we in- stantly detect another. Let two trains, running at a speed of thirty-six yards a second,' approach each oth- er. Let the whistle of one sound the note E, three hundred and twenty -three vibrations per second. It will be heard on the other as the note G, three hun- dred and eighty -eight vibrations per second; for the speed of each train crowds the vibrations into one-tenth less room, adding 32+ vibrations per second, making three hundred and eighty-eight in all. The trains pass. The vibrations are put into one -tenth more space by the whistle making them, and the other train allows only nine-tenths of what there are to overtake the ear. Each subtracts 32+ vibrations from three hundred and twenty-three, leaving only two hundred and fifty-eight, which is the note C. Yet the note E was constantly uttered. If a source of light approach or depart, it will have a similar effect on the light waves. How shall we detect it ? If a star approach us, it puts a greater number of waves into an inch, and shortens their length. If it re- cedes, it increases the length of the wave puts a less number into an inch. If a body giving only the num- ber of vibrations we call green were to approach suf- ficiently fast, it would crowd in vibrations enough to appear what we call blue, indigo, or even violet, accord- ing to its speed. If it receded sufficiently fast, it would leave behind it only vibrations enough to fill up the THE SPECTROSCOPE. 53 space with what we call yellow, orange, or red, accord- ing to its speed ; yet it would be green, and green only, all the time. But how detect the change ? If red waves are shortened they become orange in color; and from below the red other rays, too far apart to be seen by the eye, being shortened, become visible as red, and we can- not know that anything has taken place. So, if a star recedes fast enough, violet vibrations being lengthened become indigo ; and from above the violet other rays, too short to be seen, become lengthened into visible vio- let, and we can detect no movement of the colors. The dark lines of the spectrum are the cutting out of rays of definite wave-lengths. If the color spectrum moves away, they move with it, and away from their proper place in the ordinary spectrum. If, then, we find them toward the red end, the star is receding ; if toward the violet end, it is approaching. Turn the instrument on the centre of the sun. The dark lines take their appro- priate place, and are recognized on the ruled scale. Turn it on one edge, that is approaching us one and a quarter miles a second by the revolution of the sun on its axis, the spectral lines move toward the violet end ; turn the spectroscope toward the other edge of the sun, it is re- ceding from us one and a quarter miles a second by reason of the axial revolution, and the spectral lines move toward the red end. Turn it near the spots, and it reveals the mighty up -rush in one place and the down-rush in another of one hundred miles a second. We speak of it as an easy matter, but it is a problem of the greatest delicacy, almost defying the mind of man to read the movements of matter. It should be recognized that Professor Young, of 54 ASTRONOMICAL INSTRUMENTS. Princeton, is the most successful operator in this recent realm of science. He already proposes to correct the former estimate of the sun's axial rotations, derived from observing its spots, by the surer process of observ- ing accelerated and retarded light. Within a very few years this wonderful instrument, the spectroscope, has made amazing discoveries. In chemistry it reveals substances never known before ; in analysis it is delicate to the detection of the mill- ionth of a grain. It is the most deft handmaid of chemistry, the arts, of medical science, and astronomy. It tells the chemical constitution of the sun, the move- ments taking place, the nature of comets, and nebulae. By the spectroscope we know that the atmospheres of Venus and Mars are like our own ; that those of Jupi- ter and Saturn are very unlike ; it tells us which stars approach and which recede, and just how one star dif- fereth from another in glory and substance. In the near future we shall have the brilliant and diversely colored flowers of the sky as well classified into orders and species as are the flowers of the earth. CELESTIAL MEASUREMENTS. "Who hath measured the waters in the hollow of his hand, and meted out heaven with the span ? Mine hand also hath laid the foundation of the earth, and my rignt hand hath spanned the heavens." Isa. xl. 12; xlviii. 13. * Go to yon tower, where busy science plies Her vast antennae, feeling thro' the skies; That little vernier, on whose slender lines The midnight taper trembles as it shines, A silent index, tracks the planets' inarch In all their wanderings thro' the ethereal arch, Tells through the mist where cazzled Mercury burns, And marks the spot where Uranus returns. *' So, till by wrong or negligence effaced, The living index which thy Maker traced Repeats the line each starry virtue draws Through the wide circuit of creation's laws: Still tracks unchanged the everlasting ray Where the dark shadows of temptation stray ; But, once defaced, forgets the orbs of light, And leaves thee wandering o'er the expanse of night." OLIVER WENDELL HOLMES. USES OF ASTRONOMY. 57 IY. CELESTIAL MEASUREMENTS. WE know that astronomy has what are called practi- cal uses. If a ship had been driven by Euroclydon for fourteen dismal days and nights without sun or star ap- pearing, a moment's glance into the clear sky from the heaving deck, by a very slightly educated sailor, would tell within one hundred rods where he was, and de- termine the distance and way to the nearest port. We know that, in all final and exact surveying, positions must be fixed by the stars. Earth's landmarks are un- certain and easily removed ; those which we get from the heavens are stable and exact. In 1878 the United States steam -ship Enterprise was sent to survey the Amazon. Every night a "star party" went ashore to fix the exact latitude and lon- gitude by observations of the stars. Our real land- marks are not the pillars we rear, but the stars millions of miles away. All our standards of time are taken from the stars ; every railway train runs by their time to avoid collision ; by them all factories start and stop. Indeed, we are ruled by the stars even more than the old astrologers imagined. Man's finest mechanism, highest thought, and broad- est exercise of the creative faculty have been inspired by astronomy. No other instruments approximate in delicacy those which explore the heavens; no other 3* 58 CELESTIAL MEASUREMENTS. system of thought can draw such vast and certain con- clusions from its premises. " Too low they build who build beneath the stars ;" we should lay our foundations in the skies, and then build upward. We have been placed on the outside of this earth, in- stead of the inside, in order that we may look abroad. We are carried about, through unappreciable distance, at the inconceivable velocity of one thousand miles a minute, to give us different points of vision. The earth, on its softly-spinning axle, never jars enough to unnest a bird or wake a child ; hence the foundations of our observatories are firm, and our measurements ex- act. Whoever studies astronomy, under proper guid- ance and in the right spirit, grows in thought and feel- ing, and becomes more appreciative of the Creator. Celestial Movements. Let it not be supposed that a mastery of mathematics and a finished education are necessary to understand the results of astronomical research. It took at first the highest power of mind to make the discoveries that are now laid at the feet of the lowliest. It took sublime faith, courage, and the results of ages of experience in navigation, to enable Columbus to discover that path to the New World which now any little boat can follow. Ages of experience and genius are stored up in a loco- motive, but quite an unlettered man can drive it. It is the work of genius to render difficult matters plain, abstruse thoughts clear. A brief explanation of a few terms will make the prin- ciples of world inspection easily understood. Imagine a perfect circle thirty feet in diameter that is } create ZTHflS OF ASTRONOMY. 59 one (Fig. 19). Draw through it a diameter horizontally, another perpendicularly. The angles made by the intersecting lines are each said to be ninety degrees, marked thus . The arc of a circle included between any two of the lines is also 90. Every cir- cle, great or small, is divided into these 360. If the sun rose in the east and came to the zenith at noon, it would have passed 90. When it set in the west it would have traversed half the circle, or 180. In Fig. 20 the angle of the lines meas- Fig. 20. Illustration of Angles. ured on the graduated arc is 10. The mountain is 10 high, the world 10 in diameter, the comet moves 10 a day, the stars are 10 apart. The height of the moun- tain, the diameter of the world, the velocity of the comet, and the distance between the stars, depend on the distance of each from the point of sight. Every degree is divided into 60 minutes (marked '), and every minute into 60 seconds (marked "). Imagine yourself inside a perfect sphere one hundred feet in diameter, witli the interior surface above, around, and below studded with fixed bright points like stars. The familiar constellations of night might be blazoned there in due proportion. If this star-sprent sphere were made to revolve once in twenty-four hours, all the stars would successively 60 CELESTIAL MEASUREMENTS. pass in review. How easily we could measure distances between stars, from a certain fixed meridian, or the equator ! How easily we could tell when any particular star would culminate ! It is as easy to take all these measurements when our earthly observatory is steadi- ly revolved within the sphere of circumambient stars. Stars can be mapped as readily as the streets of a great city. Looking down on it in the night, one could trace the lines of lighted streets, and judge something of its extent and regularity. But the few lamps of even- ing would suggest little of the greatness of the public buildings, the magnificent enterprise and commerce of its citizens, or the intelligence of its scholars. Looking up to the lamps of the celestial city, one can judge something of its extent and regularity ; but they sug- gest little of the magnificence of the many mansions. Stars are reckoned as so many degrees, minutes, and seconds from each other, from the zenith, or from a giv- en meridian, or from the equator. Thus the stars called the Pointers, in the Great Bear, are 5 apart ; the near- est one is 29 from the Pole Star, which is some 40 above the horizon at Philadelphia. In going to Eng- land you creep up toward the north end of the earth, till the Pole Star is 54 high. It stays near its place among the stars continually, " Of whose true-fixed and resting quality There is no fellow in the firmament." How to Measure. Suppose a telescope, fixed to a mural circle, to revolve on an axis, as in Fig. 21 ; point it horizontally at a star ; USES OF ASTRONOMY. 61 turn it up perpendicular to another star. Of course the two stars are 90 apart, and the graduated scale, which is attached to the outer edge of the circle, shows a revolution of a quarter circle, or 90. But a perfect accuracy of measurement must be sought ; for a mistake of the breadth of a hair, seen at the distance of one hundred and twenty-five feet, would cause an error of 3,000,000 miles at the distance of the sun, and im- Fig. 21. Mural Circle. mensely more at the distance of the stars. The cor- rection of an inaccuracy of no greater magnitude than that has reduced our estimate of the distance of our sun 3,000,000 miles. Consider the nicety of the work. Suppose the grad- uated scale to be thirty feet in circumference. Divided into 360, each would be one inch long. Divide each degree into 60', each one is ^-V of an inch long. It takes good eyesight to discern it. But each minute must be 62 CELESTIAL MEASUREMENTS. divided into 60", and these must not only be noted, but even tenths and hundredths of seconds must be discern- ed. Of course they are not seen by the naked eye; some mechanical contrivance must be called in to assist. A watch loses two minutes a week, and hence is unrelia- ble. It is taken to a watch-maker that every single sec- ond may be quickened -^l^o P art * i tse ^ Now 20 ooo part of a second would be a small interval of time to measure, but it must be under control. If the tempera- ture of a summer morning rises ten or twenty degrees we scarcely notice it ; but the magnetic tasimeter meas- ures -S^QTS of a degree. Come to earthly matters. In 1874, after nearly twenty -eight years' work, the State of Massachusetts opened a tunnel nearly five miles long through the Hoosac Mountains. In the early part of the work the engineers sunk a shaft near the middle 1028 feet deep. Then the question to be settled was where to go so as to meet the approaching excavations from the east and west. A compass could not be relied on under a moun- tain. The line must be mechanically fixed. A little divergence at the starting-point would become so great, miles away, that the excavations might pass each other without meeting; the grade must also rise toward the central shaft, and fall in working away from it ; but the lines were fixed with such infinitesimal accuracy that, when the one going west from the eastern portal and the one going east from the shaft met in the heart of the mountain, the western line was only one-eighth of an inch too high, and three-sixteenths of an inch too far north. To reach this perfect result they had to trian- gulate from the eastern portal to distant mountain USES OF ASTRONOMY. 63 peaks, and thence down the valley to the central shaft, and thus fix the direction of the proposed line across the mouth of the shaft. Plumb-lines were then drop- ped one thousand and twenty-eight feet, and thus the line at the bottom was fixed. Three attempts were made in 1867, 18TO, and 1872 to fix the exact time-distance between Greenwich and Washington. These three separate efforts do not differ one-tenth of a second. Such demonstrable results on earth greatly increase our confidence in similar measure- ments in the skies. A scale is frequently affixed to a pocket -rule, by which we can easily measure one-hundredth of an inch (Fig. 22). The upper and lower line is divided into tenths of an inch. Ob- serve the slanting line at the right hand. It leans from the perpendicular one- tenth of an inch, as shown by noticing where it reaches the top line. When it reaches the second horizontal line it has left the perpendicular one-tenth of that tenth that is, one-hundredth. The intersection marks -j^j- of an inch from one end, and one-hundredth from the other. When division-lines, on measures of great nicety, get too fine to be read by the eye, we use the microscope. By its means we are able to count 112,000 lines ruled on a glass plate within an inch. The smallest object that can be seen by a keen eye makes an angle of 40", but by putting six microscopes on the scale of the tel- escope on the mural circle, we are able to reach an exactness of 0".l, or -g-g-Vff of an inch. This instru- ment is used to measure the declination of stars, or an- 64 CELESTIAL MEASUREMENTS. gular distance north or south of the equator. Thus a star's place in two directions is exactly fixed. When the telescope is mounted on two pillars instead of the face of a wall, it is called a transit instrument. This is used to determine the time of transit of a star over the meridian, and if the transit instrument is provided with a graduated circle it can also be used for the same purposes as the mural circle. Man's capacity to meas- ure exactly is indicated in his ascertainment of the length of waves of light. It is easy to measure the three hundred feet distance between the crests of storm-waves in the wide Atlantic ; easy to measure the different wave-lengths of the different tones of musical sounds. So men measure the lengths of the undula- tions of light. The shortest is of the violet light, 154.84 ten-rnillionths of an inch. By the horizontal pendulum Professor Koot has made a 6 V of an inch apparent. The next elements of accuracy must be perfect time and perfect notation of time. As has been said, we get our time from the stars. Thus the infinite and heavenly dominates the finite and earthly. Clocks are set to the invariable sidereal time. Sidereal noon is when we have turned ourselves under the point where the sun crosses the equator in March, called the vernal equinox. Sidereal clocks are figured to indicate twenty- four hours in a day : they tick exact seconds. To map stars we wish to know the exact second when they cross the meridian, or the north and south line in the celestial dome above us. The telescope (Fig. 21, p. 61) swings ex- actly north and south. In its focus a set of fine threads of spider-lines is placed (Fig. 23). The telescope is set just high enough, so that by the rolling over of the earth USES OF ASTRONOMY. 65 Fig. 23 Transit of a Star noted. the star will come into the field just above the horizon- tal thread. The observer notes the exact second and tenth of a second when the star reaches each vertical thread in the instrument, adds together the times and divides by five to get the average, and the exact time is reached. But man is not reliable enough to observe and record with sufficient accuracy. Some, in their excitement, an- ticipate its positive passage, and some cannot get their slow mental machinery in motion till after it has made the transit. Moreover, men fall into a habit of esti- mating some numbers of tenths of a second oftener than others. It will be found that a given observer will say three tenths or seven tenths oftener than four or eight, He is falling into ruts, and not trustworthy. General O. M. Mitchel, who had been director of the Cincinnati Observatory, once told one of his staff -offi- cers that he was late at an appointment. " Only a few minutes," said the officer, apologetically. "Sir," said the general, " where I have been accustomed to work, hundredth! of a second are too important to be neglected." And it is to the rare genius of this astron- omer, and to others, that we owe the mechanical accu- racy that we now attain. The clock is made to mark its seconds on paper wrapped around a revolving cylinder. Under the observer's fingers is an electric key. This iie can touch at the instant of the transit of the star 66 CELESTIAL MEASUREMENTS. over each wire, and thus put his observation on the same line between the seconds dotted by the clock. Of course these distances can be measured to minute fractional parts of a second. But it has been found that it takes an appreciable time for every observer to get a thing into his head and out of his finger-ends, and it takes some observers longer than others. A dozen men, seeing an electric spark, are liable to bring down their recording marks in a dozen different places on the revolving paper. Hence the time that it takes for each man to get a thing into his head and out of his fingers is ascertained. This time is called his personal equation, and is subtracted from all of his observations in order to get at the true time ; so willing are men to be exact about material matters. Can it be thought that moral and spiritual matters have no precision? Thus distances east or west from any given star or meridian are secured ; those north and south from the equator or the zenith are as easily fixed, and thus we make such accurate maps of the heavens that any movements in the far-off stars so far that it may take centuries to render the swiftest movements appreciable may at length be recognized and account- ed for. We now come to a little study of the modes of measuring distances. Create a perfect square (Fig. 24); draw a diagonal line. The square angles are 90, the divided angles give two of 45 each. Now the base A B is equal to the perpendicu- lar A C. Now any point C, where a Fig. 24. perpendicular, A C 3 and a diagonal, B 0, meet will be USES OF ASTRONOMY. 67 r \ as far from A as B is. It makes no difference if a river flows between A and C, and we cannot go over it ; we can measure its distance as easily as if we could. Set a table four feet by ^ eight out-doors (Fig. 25) ; so arrange it / that, looking along one end, the line / j of sight just strikes a tree the other / ', side of the river. Go to the other ... ,, ^\ _ j .^. end, and, looking toward the tree, you find the line of sight to the tree falls an inch from the end of the table on the farther side. The lines, therefore, approach each other one inch in every four feet, and will come together at a tree three hundred and eighty -four feet away. The next process is to measure the Fig. 25. Measuring DIB- height or magnitude of objects at an ascertained distance. Put two pins in a stick half an inch apart (Fig. 26). Hold it up two feet from the eye, Fig. 26. Measuring Elevations. and let the upper pin fall in line with your eye and the top of a distant church steeple, and the lower pin in line with the bottom of the church and your eye. If the church is three-fourths of a mile away, it must be eighty-two feet high ; if a mile away, it must be one hundred and ten feet high. For if two lines spread (J8 CELESTIAL MEASUREMENTS. one-half an inch going two feet, in going four feet they will spread an inch, and in going a mile, or five thou- sand two hundred and eighty feet, they will spread out one -fourth as many inches, viz., thirteen hundred and twenty that is, one hundred and ten feet. Of course these are not exact methods of measurement, and would not be correct to a hair at one hundred and twenty-five feet, but they perfectly illustrate the true methods of measurement. Imagine a base line ten inches long. At each end erect a perpendicular line. If they are carried to in- finity they will never meet : will be forever ten inches apart. But at the distance of a foot from the base line incline one line toward the other 10000000 f an inch, and the lines will come together at a distance of three hundred miles. That new angle differs from the for- mer right angle almost infinitesimally, but it may be measured. Its value is about three-tenths of a second. If we lengthen the base line from ten inches to all the miles we can command, of course the point of meet- ing will be proportionally more distant. The angle made by the lines where they come together will be obviously the same as the angle of divergence from a right angle at this end. That angle is called the parallax of any body, and is the angle that would be made by two lines coming from that body to the two ends of any conventional base, as the semi-diameter of the earth. That that angle would vary according to the various dis- tances is easily seen by Fig. 27. Let O P be the base. This would subtend a greater angle seen from star A than from star B. Let B be far enough away, and O P would become invisible, and B USES OF ASTRONOMY. 69 would have no parallax for that base. Thus the moon has a parallax of 57' with the semi-equatorial diameter of the earth for a base. And the sun has a parallax 8". 85 on the same base. It is not necessary to confine ourselves to right angles in these measurements, for the same principles hold true in any angles. Now, suppose two observers on the equator should look at the inoon at the same instant. One is on the top of Cotopaxi, on the west coast of South America, and one on the west coast of Africa. They are 90 apart half the earth's diam- eter between them. The one on Cotopaxi sees it exactly overhead, at an angle of 90 with the earth's diameter. The one on the coast of Africa sees its angle with the same line to be 89 3' that is, its parallax is 57'. Try the same experiment on the sun farther away, as is seen in Fig. 27, and its smaller parallax is found to be only 8".85. It is not necessary for two observers to actually sta- tion themselves at two distant parts of the earth in order to determine a parallax. If an observer could go from one end of the base-line to the other, he could determine both angles. Every observer is actually car- ried along through space by two motions : one is that of the earth's revolution of one thousand miles an hour around the axis ; and the other is the movement of the earth around the sun of one thousand miles in a minute. Hence we can have the diameter not only of 70 CELESTIAL MEASUREMENTS. the earth (eight thousand miles) for a base-line, but the diameter of the earth's orbit (185,000,000 miles), or any part of it, for such a base. Two observers at the ends of the earth's diameter, looking at a star at the same in- stant, would find that it made the same angle at both ends; it has no parallax on so short a base. We must seek a longer one. Observe a certain star on the 21st of March ; then let us traverse the realms of space for six months, at one thousand miles a minute. We come round in our orbit to a point opposite where we were six months ago, with 184,000,000 of miles between the points. Now, with this for a base-line, measure the an- gles of the same stars: it is the same angle. Sitting in ray study here, I glance out of the window and dis- cern separate bricks, in houses five hundred feet away, with my unaided eye ; they subtend a discernible an- gle. But one thousand feet away I cannot distinguish individual bricks ; their width, being only two inches, does not subtend an angle apprehensible to my vision. So at these distant stars the earth's enormous orbit, if lying like a blazing ring in space, with the world set on its edge like a pearl, and the sun blazing like a diamond in the centre, would all shrink to a mere point. Not quite to a point from the nearest stars, or we should never be able to measure the distance of any of them. Professor Airy says that our orbit, seen from the nearest star, would be the same as a circle six-tenths of an inch in diameter seen at the distance of a mile : it would all be hidden by a thread one-twenty-fifth of an inch in diameter, held six hundred and fifty feet from the eye. If a straight line could be drawn from a star, Sirius in the east to the star Yega in the west, touching our USES OF ASTRONOMY. 71 earth's orbit on one side, as T K A (Fig. 28), and a line were to be drawn six B A T months later from the same stars, touching our earth's orbit on the oth- erside,asRBT,sucha line would not diverge sufficiently from a straight line for us to detect its divergence. Numerous vain at- tempts had been made, up to the year 1835, to detect and measure the angle of parallax by which we could rescue some one or more of the stars from the inconceiv- able depths of space, and ascertain their distance from us. We are ever impelled to triumph over what is de- clared to be unconquerable. There are peaks in the Alps no man has ever climbed. They are assaulted every year by men zealous of more worlds to conquer. So these greater heights of the heavens have been as- saulted, till some ambitious spirits have outsoared even imagination by the certainties of mathematics. It is obvious that if one star were three times as far from us as another, the nearer one would seem to be displaced by our movement in our orbit three times as much as the other ; so, by comparing one star with an- other, we reach a ground of judgment. The ascertain- ment of longitude at sea by means of the moon affords a good illustration. Along the track where the moon sails, nine bright stars, four planets, and the sun have been selected. The nautical almanacs give the distance of the moon from these successive stars every hour in the night for three years in advance. The sailor can measure the distance at any time by his sextant. Looking from the world at D (Fig. 29), the distance of the moon and 72 CELESTIAL MEASUREMENTS. star is A E, which is given in the almanac. Looking from C, the distance is only B E, which enables even the uneducated sailor to find the distance, C D, on the earth, or his distance from Greenwich. J Fig. 29. Mode of Ascertaining Longitude. So, by comparisons of the near and far stars, the ap- proximate distance of a few of them has been deter- mined. The nearest one is the brightest star in the Centaur, seldom visible in our northern latitudes, which has a parallax of about one second. The next nearest is No. 61 in the Swan, or 61 Cygni, having a parallax of 0".34:. Approximate measurements have been made on Sirius, Capella, the Pole Star, etc., about eighteen in all. The distances are immense: only the swiftest agents can traverse them. If our earth were suddenly to dis- solve its allegiance to the king of day, and attempt a flight to the North Star, and should maintain its flight of one thousand miles a minute, it would fly away to- ward Polaris for thousands upon thousands of years, till a million years had passed away, before it reached that northern dome of the distant sky, and gave its new alle- giance to another sun. The sun it had left behind it would gradually diminish till it was small as Arcturus, then small as could be discerned by the naked eye, until at last it would finally fade out in utter darkness long before the new sun was reached. Light can trav- erse the distance around our earth eight times in one second. It comes in eight minutes from the sun, but it takes three and a quarter years to come from Alpha USES OF ASTRONOMY. 73 Centauri, seven and a quarter years from 61 Cjgni, and forty-five years from the Polar Star. Sometimes it happens that men steer along a lee shore, dependent for direction on Polaris, that light- house in the sky. Sometimes it has happened that men have traversed great swamps by night when that star was the light-house of freedom. In either case the exigency of life and liberty was provided for forty-five years before by a Providence that is divine. We do not attempt to name in miles these enormous distances ; we must seek another yard-stick. Our astro- nomical unit and standard of measurement is the dis- tance of the earth from the sun 92,500,000 miles. This is the golden reed with which we measure the celestial city. Thus, by laying down our astronomi- cal unit 226,000 times, we measure to Alpha Centauri, more than twenty millions of millions of miles. Doubt- less other suns are as far from Alpha Centauri and each other as that is from ours. Stars are not near or far according to their brightness. 61 Cygni is a telescopic star, while Sirius, the brightest star in the heavens, is twice as far away from us. One star differs from another star in intrinsic glory. The highest testimonies to the accuracy of these ce- lestial observations are found in the perfect predictions of eclipses, transits of planets over the sun, occupation of stars by the moon, and those statements of the Nau- tical Almanac that enable the sailor to know exactly where he is on the pathless ocean by the telling of the stars : " On the trackless ocean this book is the mariner's trusted friend and counsellor; daily and nightly its revelations bring safety to ships in all parts of the 74 CELESTIAL MEASUREMENTS. world. It is something more than a mere book ; it is an ever-present manifestation of the order and harmony of the universe." Another example of this wonderful accuracy is found in tracing the asteroids. Within 200,000,000 or 300,000,000 miles from the sun, the two hundred and fifty (Sep- tember, 1885.) minute bodies that have been already discovered move in paths very nearly the same indeed two of them traverse the same orbit, being one hundred and eighty degrees apart ; they look alike, yet the eye of man in a few observations so determines the curve of each orbit, that one is never mistaken for another. But astronomy has higher uses than fixing time, estab- lishing landmarks, and guiding the sailor. It greatly quickens and enlarges thought, excites a desire to know, leads to the utmost exactness, and ministers to adora- tion and love of the Maker of the innumerable suns. THE SUN. "And God marie two great lights; the greater light to rule the day. and the lesser light to rule the night : he made the stars also." Gen. i. 16. " It is perceived that the sun of the world, with all its essence, which is heat and light, flows into every tree, and into every shrub and flower, and into every stone, mean as well as precious ; and that every object takes its portion from this common influx, and that the sun does not divide its light and heat, and dispense a part to this and a part to that. It is simi- lar with the sun of heaven, from which the Divine love proceeds as heat, and the Divine wisdom as light; these two flow into human minds, as the heat and light of the sun of the world into bodies, and vivify them ac- cording to the quality of the minds, each of which takes from the com- mon influx as much as is necessary." SWEDENBOBG. THE SUN. 77 v. THE SUN. SUPPOSE we had stood on the dome of Boston State- house November 9th, 1872, on the night of the great conflagration, and seen the fire break out; seen the en- gines dash through the streets, tracking their patli by their sparks; seen the fire encompass a whole block, leap the streets on every side, surge like the billows of a storm-swept sea ; seen great masses of inflammable gas rise like dark clouds from an explosion, then take fire in the air, and, cut off from the fire below, float like argosies of flame in space. Suppose we had felt the wind that came surging from all points of the compass to fan that conflagration till it was light enough a mile away to see to read the finest print, hot enough to de- compose the torrents of water that were dashed on it, making new fuel to feed the flame. Suppose we had seen this spreading fire seize on the whole city, extend to its environs, and, feeding itself on the very soil, lick up Worcester with its tongues of flame Albany, New York, Chicago, St. Louis, Cincinnati and crossing the plains swifter than a prairie fire, making each peak of the Rocky Mountains hold up aloft a separate torch of flame, and the Sierras w r hiter with heat than they ever were with snow, the waters of the Pacific resolve into their constituent elements of oxygen and hydrogen, and 78 A SOLAR SYSTEM. burn with unquenchable fire! We withdraw into the air, and see below a world on fire. All the prisoned powers have burst into intensest activity. Quiet breezes have become furious tempests. Look around this flam- ing globe on fire above, below, around there is noth- ing but fire. Let it roll beneath us till Boston comes round again. No ember has yet cooled, no spire of flame has shortened, no surging cloud has been quiet- ed. Not only are the mountains still in flame, but other ranges burst up out of the seething sea. There is no place of rest, no place not tossing with raging flame ! Yet all this is only a feeble figure of the great burn- ing sun. It is but the merest hint, a million times too insignificant. The sun appears small and quiet to us because we are so far away. Seen from the various planets, the rela- tive size of the sun appears as in Fig. 30. Looked for from some of the stars about us, the sun could not be seen at all. Indeed, seen from the earth, it is not al- ways the same size, because the distance is not always the same. If we represent the size of the sun by one thousand on the 23d of September or 21st of March, it would be represented by nine hundred and sixty-seven on the 1st of July, and by one thousand and thirty -four on the 1st of January. We sometimes speak of the sun as having a diameter of 860,000 miles. We mean that that is the extent of the body as seen by the eye. But that is a small part of its real diameter. So we say the earth has an equa- torial diameter of 7925 miles, and a polar one of 7899. But the air is as much a part of the earth as the rocks are. The electric currents are as much a part of the THE SUN. 79 earth as the ores and mountains they traverse. What the diameter of the earth is, including these, no man can tell. We used to say the air extended forty-five miles, but we now know that it reaches vastly farther. So of Fig. 30. Relative Size of Snn as seen from Different Planets. the sun, we might almost say that its diameter is infi- nite, for its light and heat reach beyond our measure- ment. Its living, throbbing heart sends out pulsations, keeping all space full of its tides of living light. 80 A SOLAR SYSTEM. Fig. 31 Zodiacal Light. We might say with evident truth that the far-off planets are a part of the sun, since the space they trav- erse is filled with the power of that controlling king ; not only with light, but also with gravitating power. But come to more ponderable matters. If we look THE SUN. 81 into our western sky soon after sunset, on a clear, moon- less night in March or April, we shall see a dim, soft light, somewhat like the milky- way, often reaching, well defined, to the Pleiades. It is wedge-shaped, in- clined to the south, and the smallest star can easily be seen through it. Mai ran and Cassini affirm that they have seen sudden sparkles and movements of light in it. All our best tests show the spectrum of this light to be continuous, and therefore reflected ; which indicates that it is a ring of small masses of meteoric matter surround- ing the sun, revolving with it and reflecting its light. One bit of stone as large as the end of one's thumb, in a cubic mile, would be enough to reflect what light we see looking through millions of miles of it. Perhaps an eye sufficiently keen and far away would see the sun surrounded by a luminous disk, as Saturn is with his rings. As it extends beyond the earth's orbit, if this be measured as a part of the sun, its diameter would be about 200,000,000 miles. Come closer. When the sun is covered by the disk of the moon at the instant of total eclipse, observers are startled by strange swaying luminous banners, ghostly and weird, shooting in changeful play about the central darkness (Fig. 32). These form the corona. Men have usually been too much moved to describe them, and have always been incapable of drawing them in the short minute or two of their continuance. But in 1878 men travelled eight thousand miles, coining and return- ing, in order that they might note the three minutes of total eclipse in Colorado. Each man had his work as- signed to him, and he was drilled to attend to that and nothing else. Improved instruments were put into his 4* A SOLAR SYSTEM. hands, so that the sun was made to do his own drawing and give his own picture at consecutive instants. Fig. 33 is a copy of a photograph of the corona of 1878, by Fig. 32. The Corona in 1858, Brazil. Mr. Henry Draper. It showed much less changeability that year than common, it being very near the time of least sun-spot. The previous picture was taken near the time of maximum sun-spot. It was then settled that the corona consists of re- flected light, sent to us from dust particles or meteor- oids swirling in the vast seas, giving new densities and THE SUN. 83 rarities, and hence this changeful light. Whether they are there by constant projection, and fall again to the sun, or are held by electric influence, or by force of or- bital revolution, we do not know. That the corona can- not be in any sense an atmosphere of any continuous gas, is seen from the fact that the comet of 1843, pass- ing within 93,000 miles of the body of the sun, was not burned out of existence as a comet, nor in any percepti- Fig. 33. The Ooroua iu 1STS, Colorado. ble degree retarded in its motion. If the sun's diameter is to include the corona, it will be from 1,260,000 to 1,460,000 miles. 84 A SOLAk SYSTEM. Come closer still. At the instant of the totality of the eclipse red flames of most fantastic shape play along the edge of the moon's disk. They can be seen at any time by the use of a proper telescope with a spectro- scope attached. I have seen them with great distinct- ness and brilliancy with the excellent eleven-inch tele- scope of the Wesleyan University. A description of their appearance is best given in the language of Professor Young, of Princeton College, who has made these flames the object of most successful study. On September 7th, 1871, he was observing a large hydrogen cloud by the sun's edge. This cloud was about 100,000 miles long, and its upper side was some 50,000 miles above the sun's surface, the lower side some 15,000 miles. The whole had the appearance of being supported on pillars of fire, these seeming pillars being in reality hydrogen jets brighter and more active than the substance of the cloud. At half -past twelve, when Professor Young chanced to be called away from his observatory, there were no indications of any approaching change, except that one of the connecting stems of the southern extrem- ity of the cloud had grown considerably brighter and more curiously bent to one side ; and near the base of another, at the northern end, a little brilliant lump had developed itself, shaped much like a summer thunder- head. But when Professor Young returned, about half an hour later, he found that a very wonderful change had taken place, and that a very remarkable process was act- ually in progress. " The whole thing had been literally blown to shreds," he says, " by some inconceivable up- rush from beneath. In place of the quiet cloud I had Fig. 34. Solar Prominences of Flaming Hydrogei THE SUN. 87 left, the air if I may use the expression was filled with the flying debris, a mass of detached vertical fusi- form fragments, each from ten to thirty seconds (i. e., from four thousand five hundred to thirteen thousand five hundred miles) long, by two or three seconds (nine hundred to thirteen hundred and fifty miles) wide brighter, and closer together where the pillars had for- merly stood, and rapidly ascending. When I looked, some of them had already reached a height of nearly four minutes (100,000 miles); and while I watched them they arose with a motion almost perceptible to the eye, until, in ten minutes, the uppermost were more than 200,000 miles above the solar surface. This was ascertained by careful measurements, the mean of three closely accordant determinations giving 210,000 miles as the extreme altitude attained. I am particular in the statement, because, so far as I know, chromato- spheric matter (red hydrogen in this case) has never before been observed at any altitude exceeding five minutes, or 135,000 miles. The velocity of ascent, also one hundred and sixty -seven miles per second is considerably greater than anything hitherto recorded. * * * As the filaments arose, they gradually faded away like a dissolving cloud, and at a quarter past one only a few filmy wisps, with some brighter streamers low down near the chrotnatosphere, remained to mark the place. But in the mean while the little ' thunder-head' before alluded to had grown and developed wonder- fully into a mass of rolling and ever-changing flame, to speak according to appearances. First, it was crowd- ed down, as it were, along the solar surface ; later, it arose almost pyramidally 50,000 miles in height ; then 88 A SOLAR SYSTEM. its summit was drawn down into long filaments and threads, which were most curiously rolled backward and forward, like the volutes of an Ionic capital, and finally faded away, and by half-past two had vanished like the other. The whole phenomenon suggested most forcibly the idea of an explosion under the great prominence, acting mainly upward, but also in all directions out- ward ; and then, after an interval, followed by a corre- sponding in-rush." No language can convey nor mind conceive an idea of the fierce commotion we here contemplate. If we call these movements hurricanes, we must remember that what we use as a figure moves but one hundred miles an hour, while these move one hundred miles a second. Such storms of fire on earth, " coming down upon us from the north, would, in thirty seconds after they had crossed the St. Lawrence, be in the Gulf of Mexico, carrying with them the whole surface of the continent in a mass not simply of ruins but of glowing vapor, in which the vapors arising from the dissolution of the materials composing the ci'ties of Boston, New York, and Chicago would be mixed in a single indis- tinguishable cloud." In the presence of these evident visions of an actual body in furious flame, we need hes- itate no longer in accepting as true the words of St. Peter of the time " in which the [atmospheric] heav ens shall pass away with a great noise, and the ele- ments shall melt with fervent heat ; the earth also, and the works that are therein, shall be burned up." This region of discontinuous flame below the corona is called the chromosphere. Hydrogen is the principal material of its upper part ; iron, magnesium, and other THE SlTtf. 89 metals, some of them as yet unknown on earth, but hav- ing a record in the spectrum, in the denser parts below. If these fierce fires are a part of the sun, as they as- suredly are, its diameter would be from 1,060,000 to 1,260,000 miles. Let us approach even nearer. We see a clearly recog- nized even disk, of equal dimensions in every direction. This is the photosphere. We here reach some definite- ly measurable data for estimating its visible size. We already know its distance. Its disk subtends an angle of 32' 4" 2", or a little more than half a degree. Three hundred and forty such suns, laid side by side, would span the celestial arch from east to west with a half circle of light. Two lines drawn from our earth at the angle mentioned would be 860,000 miles apart at the distance of 92,500,000 miles. This, then, is the diameter of the visible and measurable part of the sun. It would require one hundred and eight globes like the earth in a line to measure the sun's diameter, and three hundred and thirty-nine, to be strung like the beads of a neck lace, to encircle his waist. The sun has a volume equal to 1.245,000 earths, but being about a quarter as dense, it has a mass of only 326.800 earths. It has seven hun- dred times the mass of all the planets, asteroids, and satellites put together. Thus it is able to control them all by its greater power of attraction. Concerning the condition of the surface of the sun many opinions are held. That it is hot beyond all esti- mate is indubitable. Whether solid or gaseous we are not sure. Opinions differ : some incline to the first theory, others to the second ; some deem the sun com- posed of solid particles, floating in gas so condensed 90 A SOLAR SYSTEM. by pressure and attraction as to shine like a solid, it has no sensible changes of general level, but has pro- digious activity in spots. These spots have been the objects of earnest and almost hourly study on the part of such men as Secchi, Lockyer, Faye, Young, and oth- ers, for years. But it is a long way off to study an ob- ject. No telescope brings it nearer than 100,000 miles. Theory after theory has been advanced, each one satis- factory in some points, none in all. The facts about the spots are these : They are most abundant on the two Bides of the equator. They are gregarious, depressed below the surface, of vast extent, black in the centre, usually surrounded by a region of partial darkness, be- yond which is excessive light. They have motion of their own over the surface motion rotating about an axis, upward and downward about the edges. They change their apparent shape as the sun carries them Pig. 35. Change in Spots as rotated across the Disk, showing Cavities. across its disk by axial revolution, being narrow as they present their edges to us, and rounder as we look per- pendicularly into them (Fig. 35). These spots are also very variable in number, some- times there being none for nearly two hundred days, and again whole years during which the sun is never with- out them. The period from maximum to maximum THE SUN. 91 of spots is about eleven years. We might have looked for them in vain in 1878. They were numerous in 1884, and will be in 1894 if not again delayed. The cause of this periodicity was inferred to be the near approach of the enormous planet Jupiter, causing disturbance by its attraction. But the periods do not correspond, and the cause is the result of some law of solar action to us as yet unknown. These spots may be seen with almost any telescope, the eye being protected by deeply colored glasses. Until within one hundred years they were supposed to be islands of scoriae floating in the sea of molten matter. But they were depressed below the surface, and showed a notch when on the edge. Wilson origi- nated and Herschel developed the theory that the sun's real body was dark, cool, and habitable, and that the photosphere was a luminous stratum at a distance from the real body, with openings showing the dark spots below. Such a sun would have cooled off in a week, but would previously have annihilated all life below. The solar spots being most abundant on the two sides of the equator, indicates their cyclonic character; the centre of a cyclone is rarefied, and therefore colder, and cold on the sun is darkness. M. Faye says : " Like our cyclones, they are descending, as I have proved by a special study of these terrestrial phenomena. They carry down into the depths of the solar mass the cooler materials of the upper layers, formed principally of hydrogen, and thus produce in their centre a decided extinction of light and heat as long as the gyratory movement continues. Finally, the hydrogen set free at the base of the whirlpool becomes reheated at this 92 A SOLAR SYSTEM. great depth, and rises up tmnultuonsly around the whirl- pool, forming irregular jets, which appear above the chromosphere. These jets constitute the protuberances. The whirlpools of the sun, like those on the earth, are of all dimensions, from the scarcely visible pores to the enormous spots which we see from time to time. They Fig. 36. Solar Spot, by Langley. have, like those of the earth, a marked tendency, first to increase and then to break up, and thus form a row of spots extending along the same parallel." A spot of 20,000 miles diameter is quite small; there was one 74,816 miles across, visible to the naked eye for a week in 1843. This particular sun-spot somewhat THE SUN. 93 helped the Millerites. On the day of the eclipse, in 1858, a spot over 107,000 miles in extent was clearly seen. In such vast tempests, if there were ships built as large as the whole earth, they would be tossed like autumn leaves in an ocean storm. The revolution of the sun carries a spot across its face in about fourteen days. After a lapse of as much more time, they often reappear on the other side, changed but recognizable. They often break out or disappear under the eye of the observer. They divide like a piece of ice dropped on a frozen pond, the pieces sliding off in every direction, or combine like separate floes driven together into a pack. Sometimes a spot will last for more than two hundred days, recognizable through six or eight revolutions. Sometimes a spot will last only half an hour. The velocities indicated by these movements are in- credible. An up-rush and down-rush at the sides has been measured of twenty miles a second ; a side-rush or whirl, of one hundred and twenty miles a second. These tempests rage from a few days to half a year, traversing regions so wide that our Indian Ocean, the realm of storms, is too small to be used for comparison ; then, as they cease, the advancing sides of the spots approach each other at the rate of 20,000 miles an hour; they strike together, and the rising spray of fire leaps thou- sands of miles into space. It falls again into the in- candescent surge, rolls over mountains as the sea over pebbles, and all this for eon after eon without sign of exhaustion or diminution. All these swift succeeding Himalayas of fire, where one hundred worlds could be buried, do not usually prevent the sun's appearing to our far-off eyes as a perfect sphere. 94 A SOLAR SYSTEM. What the Sun does for us. To what end does this enormous power, this central source of power, exist ? That it could keep all these gigantic forces within itself could not be expected. It is in a system where every atom is. made to affect every other atom, and every world to influence every other. The Author of all lives only to do good, to send rain on the just and unjust, to cause his sun to rise on the evil and the good, and to give his spirit, like a perpet- ually widening river, to every man to profit withal. The sun reaches his unrelaxing hand of gravitation to every other world at every instant. The tendency of every world is to fly off in a straight line. This ten- dency must be momentarily curbed, and the planet held in its true curve about the sun. These giant worlds must be perfectly handled. Their speed, amounting to seventy times as fast as that of a rifle -ball, must be managed. Each and every world may be said to be lifted momentarily and swung perpetually at rrin's- length by the power of the sun. The sun warms us. It would convey but a small idea of the truth to state how many hundreds of mill- ions of cubic miles of ice could be melted by the sun every second without quenching its heat; b ^ if any one has any curiosity to know, it is 287,200,000 cubic miles of ice per second. We journey through space which has a temperature of 200 below zero ; but we live, as it were, in a con- servatory, in the midst of perpetual winter. We are roofed over by the air that treasures the heat, floored under by strata both absorptive and retentive of heat, THE SUN. 95 aiid between the earth and air violets grow and grains ripen. The sun has a strange chemical power. It kisses the cold earth, and it blushes with flowers and matures the fruit and grain. We are feeble creatures, and the sun gives us force. By it the light winds move one-eighth of a mile an hour, the storm fifty miles, the hurricane one hundred. The force is as the square of the velocity. It is by means of the sun that the mer- chant's white-sailed ships are blown safely home. So the sun carries off the miasma of the marsh, the pollu- tion of cities, and then sends the winds to wash and cleanse themselves in the sea-spray. The water-falls of the earth turn machinery, and make Lowells and Man- chesters possible, because the sun lifted all that water to the hills. Intermingled with these currents of air are the cur- rents of electric power, all derived from the sun. These have shown their swiftness and willingness to serve man. The sun's constant force displayed on the earth is equal to 543,000,000,000 engines of 400-horse power each, working day and night; and yet the earth receives only a 3 $ i 0*0 o o o o P ar * of the whole force of the sun. Besides all this, the sun, with provident care, has made and given to us coal. This omnipotent worker has stored away in past ages an inexhaustible reservoir of his power which man may easily mine and direct, thus releasing himself from absorbing toil. EXPERIMENTS. Any one may see the spots on the sun who has a spy -glass. Darken the room and put the glass through an opening toward the sun, as shown in Fig. 37. The eye-piece should be drawn out about half an inch be- 96 A SOLAR SYSTEM. jrond its usual focusing for distant objects. The farther it is drawn, the nearer must we hold the screen for a perfect image. By holding a paper near the eye-piece, the proper direction of the instru- ment may be discovered without injury to the eyes. By this means the sun can be studied from day to day, and its spots or the transits of Mer- cury and Venus shown to any number of spectators. Fig. 37. Holding Telescope to see the Snn's Spots. First covering the eyes with very dark or smoked glasses, erect a disk of pasteboard four inches in diameter between you and the sun ; close one eye; stand near it, and the whole sun is obscured. Withdraw from it till the sun's rays just shoot over the edge of the disk on every side. Measure the distance from the eye to the disk. You will be able to de- termine the distance of the sun by the rule of three : thus, as four inches is to 860,000 miles, so is distance from eye to disk to distance from dUk to the sun. Take such measurements at sunrise, noon, and sunset, and see the apparently differing sizes due to refraction. VI. THE PLANETS, AS SEEN FROM SPACE "He hangeth the earth upon nothing." Job xxvi. 7. 5 "Let a power be delegated to a finite spirit equal to the projection of the most ponderous planet in its orbit, and, from an exhaustless magazine, let this spirit select his grand central orb. Let him with puissant arm locate it in space, and, obedient to his mandate, there let it remain forever fixed. He proceeds to select his planetary globes, which he is now re- quired to marshal in their appropriate order of distance from the sun. Heed well this distribution ; for should a single globe be misplaced, the divine harmony is destroyed forever. Let us admit that finite intelligence mav at length determine the order of combination ; the mighty host is arrayed in order. These worlds, like fiery coursers, stand waiting the command to fly. But, mighty spirit, heed well the grand step, ponder well the direction in which thou wilt launch each waiting world ; weigh well the mighty impulse soon to be given, for out of the myriads of direc- tions, and the myriads of impulsive forces, there comes but a single com- bination that will secure the perpetuity of your complex scheme. In vain does the bewildered finite spirit attempt to fathom this mighty depth. In vain does it seek to resolve the stupendous problem. It turns away, and while endued with omnipotent power, exclaims, ' Give to me infinite wis- dom, or relieve me from the impossible task !' " O. M. MITCHEL, LL.D. THE PLANETS, AS SEEN FROM SPACE. 99 VI. THE PLANETS, AS SEEN FROM SPACE. IF we were to go out into space a few millions of miles from either pole of the sun, and were endowed with wonderful keenness of vision, we should perceive certain facts, viz : That space is frightfully dark except when we look directly at some luminous body. There is no air to bend the light out of its course, no clouds or other objects to reflect it in a thousand directions. Every star is a brilliant point, even in perpetual sun- shine. The cold is frightful beyond the endurance of our bodies. There is no sound of voice in the absence of air, and conversation by means of vocal organs being impossible, it must be carried on by means of mind communication. We see below an unrevolving point on the sim that marks its pole. Ranged round in order are the various planets, each with its axis pointing in very nearly the same direction. All planets, except pos- sibly Venus, and all moons except those of Uranus and Neptune, present their equators to the sun. The direc- tion of orbital and axial revolution seen from above the North Pole would be opposite to that of the hands of a watch. The speed of this orbital revolution must be propor- tioned to the distance from the sun. The attraction oi the sun varies inversely as the square of the distance. 100 A SOLAR SYSTEM. Fig. 58. Orbita and Comparative Sizes of the Planets. It holds a planet with a certain power ; one twice as far off, with one-fourth that power. This attraction must be counterbalanced by centrifugal force ; great force from great speed when attraction is great, and small from less THE PLANETS, AS SEEN FROM SPACE, 10,1, speed when attractive power is diminished by Distance, Hence Mercury must go 29.5 miW.pefVqej^d^-Aifc&i ty times as fast as a rifle-ball that goes two-fifths of a mile in a second or be drawn into the sun; while Neptune, seventy -five times as far off, and hence at- tracted only -j-gVs as much, must be slowed down to 3.4 miles a second to prevent its flying away from the fee- bler attraction of the sun. The orbital velocity of the various planets in miles per second is as follows : Mercury 29.55 Venus 21.61 Earth 18.38 Mars H.99 Jupiter 8.06 Saturn 5.95 Uranus 4.20 Neptune 3.36 Hence, while the earth makes one revolution in its year, Mercury has made over four revolutions, or pass- ed through four years ; the slower Neptune has made only y^ of one revolution. The time of axial rotation which determines the length of the day varies with different planets. The periods of the four planets nearest the sun vary only half an hour from that of the earth, while the enor- mous bodies of Jupiter and Saturn revolve in ten and ten and a quarter hours respectively. This high rate of speed, and its resultant, centrifugal force, has aided in preventing these bodies from becoming as dense as they would otherwise be Jupiter being only 0.24 as dense as the earth, and Saturn only 0.13. This extremely rapid revolution produces a great flattening at the poles. If Jupiter should rotate four times more rapidly than it does, it could not be held together compactly. As it is, the polar diameter is five thousand miles less than the equatorial : the difference in diameters produced by the SOLAR SYSTEM. e. op the* .earth, owing to the slower motion 'abiauialiea-.jjitiVsj.l^ing only twenty -six miles. The effect of this will be more specifically treated here- after. The difference in the size of the planets is very no- ticeable. If we represent the sun by a gilded globe two feet in diameter, we must represent Vulcan and Mercury by mustard-seeds ; Yenus, by a pea ; Earth, by another ; Mars, by one-half the size ; Asteroids, by the motes in a sunbeam ; Jupiter, by a small-sized orange ; Saturn, by a smaller one ; Uranus, by a cherry ; and Neptune, by one a little larger. Apply the principle that attraction is in proportion to the mass, and a man who weighs one hundred and fifty pounds on the earth weighs three hundred and ninety-six on Jupiter, and only fifty -eight on Mars; while on the Asteroids he could play with bowlders for marbles, hurl hills like Milton's angels, leap into the fifth -story windows with ease, tumble over precipices without harm, and go around the little worlds in seven jumps. The seasons of a planet are caused by the inclination of its axis to the plane of its orbit. In Fig. 39 the ro- tating earth is seen at A, with its northern pole turning in constant sunlight, and its southern pole in constant darkness ; everywhere south of the equator is more dark- ness than day, and hence winter. Passing on to B, the world is seen illuminated equally on each side of the equator. Every place has its twelve hours' darkness and light at each revolution. But at C the axis of the earth always preserving the same direction the north- ern pole is shrouded in continual gloom. Every place THE PLANETS, AS SEEN FROM SPACE. 105 north of the equator gets more darkness than light, and hence winter. The varying inclination of the axes of the different planets gives a wonderful variety to their seasons. The sun is always nearly over the equator of Jupiter, and every place has nearly its five hours day and five hours night. The seasons of Earth, Mars, and Saturn are so much alike, except in length, that no comment is nee essary. The ice-fields at either pole of Mars are ob- served to enlarge and contract, according as it is win- ter or summer there. Saturn's seasons are each seven and a half years long. The alternate darkness and light at the poles is fifteen years long. But the seasons of Venus present the greatest anom- aly, if its assigned inclination of axis (75) can be relied on as correct, which is doubtful. Its tropic zone extends nearly to the pole, and at the same time the winter at the other pole reaches the equator. The short period of this planet causes it to present the south pole to the sun only one hundred and twelve days after it has been scorching the one at the north. This gives two win- ters, springs, summers, and autumns to the equator in two hundred and twenty-five days. If each whirling world should leave behind it a trail of light to mark its orbit, and our perceptions of form were sufficiently acute, we should see that these curves of light are not exact circles, but a little flattened into ellipses, with the sun always in one of the foci. Hence each planet is nearer to the sun at one part of its orbit than another; that point is called the perihelion, and the farthest point aphelion. This eccentricity of orbit, or distance of the sun from the centre, is very small. 5* 106 A SOLAR SYSTEM. In the case of Yenus it is only .007 of the whole, and in no instance is it more than .2, viz., that of Mercury. This makes the sun appear twice as large, bright, and hot as seen and felt on Mercury at its perihelion than at its aphelion. The earth is 3,236,000 miles nearer to the sun in our winter than summer. Hence the summer in the southern hemisphere is more intolerable than in the northern. But this eccentricity is steadily diminishing at a uniform rate, by reason of the perturbing influence of the other planets. In the case of some other planets it is steadily increasing, and, if it were to go on a suffi- cient time, might cause frightful extremes of tempera- ture ; but Lalande has shown that there are limits at which it is said, " Thus far shalt thou go, and no far- ther." Then a compensative diminution will follow. Conceive a large globe, to represent the sun, float- ing in a round pond. The axis will be inclined 7 to the surface of the water, one side of the equator be 7 below the surface, and the other side the same distance above. Let the half-submerged earth sail around the sun in an appropriate orbit. The surface of the water will be the plane of the orbit, and the water that reaches out to the shore, where the stars would be set, will be the plane of the ecliptic. It is the plane of the earth's orbit extended to the stars. The orbits of all the planets do not lie in the same plane, but are differently inclined to the plane of the ecliptic, or the plane of the earth's orbit. Going out from the sun's equator, so as to see all the orbits of the planets on the edge, we should see them inclined to that of the earth, as in Fig. 40. If the earth, and Saturn, and Pallas were lying at THE PLANETS, AS SEEN FROM SPACE. 107 Fig. 40. Inclination of the Planes of Orbits. right angles with the nodal line of their orbits, and in the same direction from the snn, and the outer bodies were to start in a direct line for the sun, they would not collide with the earth on their way ; but Saturn would pass 4,000,000 and Pallas 50,000,000 miles over our heads. From this same cause we do not see Venus and Mercury make a transit across the disk of the sun at every revolution. Fig. 41 shows a view of the orbits of the earth and Fig. 41. Inclination of Orbits of Venus and Earth. Nodal Line, D B. Venus seen not from the edge but from a position somewhat above. The point E, where Venus crosses the plane of the earth's orbit, is called the ascending node. If the earth were at B when Venus is at E, Venus would be seen on the disk of the sun, making a transit. The same would be true if the earth were at D, and Venus at the descending node F. This general view of the flying spheres is full of in- 108 A SOLAR SYSTEM. terest. While quivering themselves with thunderous noises, all is silent about them ; earthquakes may be struggling on their surfaces, but there is no hint of contention in the quiet of space. They are too distant from one another to exchange signals, except, perhaps, the fleet of asteroids that sail the azure between Mars and Jupiter. Some of these come near together, con- tinuing to fill each other's sky for days with brightness, then one gradually draws ahead. They have all phases for each other crescent, half, full, and gibbous. These hundreds of bodies fill the realm where they are with inexhaustible variety. Beyond are vast spaces cold, dark, void of matter, but full of power. Occasionally a little spark of light looms up rapidly into a world so huge that a thousand of our earths could not occupy its vast bulk. It swings its four or eight moons with per- fect skill and infinite strength ; but they go by and leave the silence unbroken, the darkness unlighted for years. Nevertheless, every part of space is full of pow- er. Nowhere in its wide orbit can a world find a place ; at no time in its eons of flight can it find an instant when the sun does not hold it in safety and life. The Outlook from the Earth. If we come in from our wanderings in space and take an outlook from the earth, we shall observe certain movements, easily interpreted now that we know the system, but nearly inexplicable to men who naturally supposed that the earth was the largest, most stable, and central body in the universe. We see, first of all, sun, moon, and stars rise in the east, mount the heavens, and set in the west. As I THE PLANETS, AS SEEN FROM SPACE. 109 revolve in my pivoted study-chair, and see all sides of the room library, maps, photographs, telescope, and windows I have no suspicion that it is the room that whirls ; bnt looking out of a car-window in a depot at another car, one cannot tell which is moving, whether it be his car or the other. In regard to the world, we have come to feel its whirl. We have noticed the pyr- amids of Egypt lifted to hide the sun ; the mountains of Hymettus hurled down, so as to disclose the moon that was behind them to the watchers on the Acropo- lis ; and the mighty mountains of Moab removed to re- veal the stars of the east. Train the telescope on any star ; it must be moved frequently, or the world will roll the instrument away from the object. Suspend a cannon-ball by a fine wire at the equator; set it vibrat- ing north and south, and it swings all day in precisely the same direction. But suspend it directly over the north pole, and set it swinging toward Washington ; in five hours after it is swinging toward the Sandwich Isl- ands ; in twelve hours, toward Siam,in Asia; in eighteen hours, toward Eome, in Italy ; and in twenty-four, to- ward Washington again, not because it has changed the plane of its vibration, but because the earth has whirled beneath it, and the torsion of the wire has not been suf- ficient to compel the plane of the original direction to change with the turning of the earth. The law of in- ertia keeps it moving in the same direction. The same experimental proof of revolution is shown in a propor- tional degree at any point between the pole and the equator. But the watchers on the Acropolis do not get turned over so as to see the moon at the same time every night. 110 A SOLAR SYSTEM. We turn down our eastern horizon, but we do not find fair Luna at the same moment we did the night before. We are obliged to roll on for some thirty to fifty min- utes longer before we find the moon. It must be go- ing in the same direction, and it takes us longer to get round to it than if it were always in the same spot ; so we notice a star near the moon one night it is 13 west of the moon the next night. The moon is going around Pig. 42. Showing the Snn's Movement among the Stars. the earth from west to east, and if it goes 13 in one day, it will take a little more than twenty-seven days to go the entire circle of 360. THE PLANETS, AS SEEN FROM SPACE. Ill In our outlook we soon observe that we do not by our revolution come to see the same stars rise at the same hour every night. Orion and the Pleiades, our familiar friends in the winter heavens, are gone from the summer sky. Have they fled, or are we turned from them ? This is easily understood from Fig. 42. When the observer on the earth at A looks into the midnight sky he sees the stars at E ; but as the earth passes on to B, he sees those stars at E four minutes sooner every night ; and at midnight the stars at F are over his head. Thus in a year, by going around the sun, we have every star of the celestial dome in our mid- night sky. We see also how the sun appears among the successive constellations. When we are at A, we see the sun among the stars at G ; but as we move to- ward B, the sun appears to move toward H. If we had observed the sun rise on the 20th of August, 1876, we should have seen it rise a little before Kegulus, and a little south of it, in such a relation as circle 1 is x-^ to the star in Fig. 43. By sunset the earth M >=olar sun spots, then we shall learn why the Jovian bright spots moved faster than the great red spot. We shall probably be convinced at the same time that the regal planet is far more in the condition of the sun than his less massive and less richlv endowed brethren. Richter says that " an angel once took a man and stripped him of his flesh, and lifted him up into space to show him the glory of the universe. When the flesh was taken away the man ceased to be cowardly, and was ready to fly with the angel past galaxy after galaxy, and infinity after in- finity, and so man and angel passed on, viewing the universe, until the sun was out of sight until our solar system appeared as a speck of light against the black empyrean, and there was only darkness. And they looked onward, and in the infinities of light before, a speck of light ap- peared, and suddenly they were in the midst of rushing worlds. But they passed beyond that system, and beyond system after system, and infinity after infinity, until the human heart sank, and the man cried out: 'End is there none of the universe of God ?' The angel strengthened the man by words of counsel and courage, and they flew on again until worlds left behind them were out of sight, and specks of light in advance were trans- formed, as they approached them, into rushing systems ; they moved over architraves of eternities, over pillars c f immensities, over architecture of galaxies, unspeakable in dimensions and duration, and the human heart sank again and called out : ' End is there none of the universe of God ?' And all the stars echoed the question with amazement: 'End is there none of the universe of God ?' And this echo found no answer. They moved on again past immensities of immensities, and eternities of eterni- ties, until in the dizziness of uncounted galaxies the human heart sank for the last time, and called out : ' End is there none of the universe of God ?' And again all the stars repeated the question, and the angel answered : ' End is there none of the universe of God. Lo, also, there is no be- ginning.'" THE OPEN PAGE OF THE HEAVENS. 195 X. THE OPEN PAGE OF THE HEAVENS. THE Greeks set their mythological deities in the skies, and read the revolving pictures as a starry poem. Not that they were the first to set the blazonry of the stars as monuments of their thought ; we read certain allu- sions to stars and asterisms as far back as the time of Job. And the Pleiades, Arcturus, and Orion are some of the names used by Him who " calleth all the stars by their names, in the greatness of his power." Homer and Hesiod, 750 B.C., allude to a few stars and groups. The Arabians very early speak of the Great Bear; but the Greeks completely nationalized the heavens. They col- onized the earth widely, but the heavens completely ; and nightly over them marched the grand procession of their apotheosized divinities. There Hercules perpetu- ally wrought his mighty labors for the good of man ; there flashed and faded the changeful star Algol, as an eye in the head of the snaky-haired Medusa ; over them flew Pegasus, the winged horse of the poet, careering among the stars ; there the ship Argo, which had ex- plored all strange seas of earth, nightly sailed in the in- finite realms of heaven; there Perseus perpetually killed the sea-monster by celestial aid, and perpetually won the chained Andromeda for his bride. Very evident was their recognition of divine help : equally evident was 196 THE STELLAR SYSTEM. their assertion of human ability and dominion. They gathered the illimitable stars, and put uncountable suns into the shape of the Great Bear the most colossal form of animal ferocity and strength across whose broad forehead imagination grows weary in flying ; but they did not fail to put behind him a representative of themselves, who forever drives him around a sky that never sets a perpetual type that man's ambition and expectation correspond to that which has always been revealed as the divine. The heavens signify much higher power and wisdom to us; we retain the old pictures and groupings for the convenience of finding individual stars. It is enough for the astronomer that we speak of a star as, right ascension, Ih. 17m., declination, 88 42'. But for most people, if not all, it is better to call it Polaris. So we might speak of a lake in latitude 42 40', longitude 79 22', but it would be clearer to most persons to say Chautauqua. For exact location of a star, right ascension and declination must be given ; but for general indica- tion its name or place in a constellation is sufficiently exact. The heaven is rather indeterminably laid out in irregular tracts, and the mythological names are pre- served. The brightest stars are then indicated in order by the letters of the Greek alphabet Alpha (a), Beta (/3), Gamma (y), etc. Stars are numbered in the order of right ascension without regard to their brilliancy. Thus No. 50 Cygni is Alpha ; E. A., 20h. 36m.l9s. No. 61 is, K. A., 21h. Om. 10s. Thus any star unknown by name is easily found. An acquaintance with the names, pecu- liarities, and movements of the stars visible at different seasons of the year is an unceasing source of pleasure. It THE OPEX PAGE OF THE HEAVENS. 197 is not vision alone that is gratified, for one fine enough may hear the morning stars sing together, and understand the speech that day uttereth unto day, and the knowl- edge that night showeth unto night. One never can be alone if he is familiarly acquainted with the stars. He rises early in the summer morning, that he may see his winter friends ; in winter, that he may gladden himself with a sight of the summer stars. He hails their suc- cessive rising as he does the coming of his personal friends from beyond the sea. On the wide ocean he is commercing with the skies, his rapt soul sitting in his eyes. Under the clear skies of the East he hears God's voice speaking to him, as to Abraham, and saying, " Look now toward the heavens, and tell the number of the stars, if thou be able to number them." A general acquaintance with the stars will be first at- tempted ; a more particular knowledge afterward. Fig. 67 (page 201) is a map of the circumpolar region, which is in full view every clear night. It revolves daily round Polaris, its central point. Toward this star, the two end stars of the Great Dipper ever point, and are in consequence called "the Pointers." The map may be held toward the northern sky in such a position as the stars may happen to be. The Great Bear, or Dipper, will be seen at nine o'clock in the evening above the pole in April and May ; west of the pole, the Pointers downward, in July and August ; close to the north ho- rizon in October and November; and east of the pole the Pointers highest, in January and .February. The names of such constantly visible stars should be familiar. In order, from the end of the tail of the Great Bear, we have J3enetnasch ,, Mizar , Little Alcor close to it, AH- 9* 196 THE STELLAR SYSTEM. their assertion of human ability and dominion. They gathered the illimitable stars, and put uncountable suns into the shape of the Great Bear the most colossal form of animal ferocity and strength across whose broad forehead imagination grows weary in flying; but they did not fail to put behind him a representative of themselves, who forever drives him around a sky that never sets a perpetual type that man's ambition and expectation correspond to that which has always been revealed as the divine. The heavens signify much higher power and wisdom to us; we retain the old pictures and groupings for the convenience of finding individual stars. It is enough for the astronomer that we speak of a star as, right ascension, Hi. 17rn., declination, 88 42'. But for most people, if not all, it is better to call it Polaris. So we might speak of a lake in latitude 42 40', longitude 79 22', but it would be clearer to most persons to say Chaufanqua. For exact location of a star, right ascension and declination must be given ; but for general indica- tion its name or place in a constellation is sufficiently exact. The heaven is rather indeterminably laid out in irregular tracts, and the mythological names are pre- served. The brightest stars are then indicated in order by the letters of the Greek alphabet Alpha (a), Beta (/3), Gamma (y), etc. Stars are numbered in the order of right ascension without regard to their brilliancy. Thus No. 50 Cygni is Alpha ; R. A., 20h. 36m.l9s. No. 61 is, R. A., 21h. Om. 10s. Thus any star unknown by name is easily found. An acquaintance with the names, pecu- liarities, and movements of the stars visible at different seasons of the year is an unceasing source of pleasure. It THE OPEN PAGE OF THE HEAVENS. 197 is not vision alone that is gratified, for one fine enough may hear the morning stars sing together, and understand the speech that day uttereth unto day, and the knowl- edge that night showeth unto night. One never can be alone if he is familiarly acquainted with the stars. He rises early in the summer morning, that he may see his winter friends; in winter, that he may gladden himself with a sight of the summer stars. He hails their suc- cessive rising as he does the coming of his personal friends from beyond the sea. On the wide ocean he is commercing with the skies, his rapt soul sitting in his eyes. Under the clear skies of the East he hears God's voice speaking to him, as to Abraham, and saying, " Look now toward the heavens, and tell the number of the stars, if thou be able to number them." A general acquaintance with the stars will be first at- tempted ; a more particular knowledge afterward. Fig. 67 (page 201) is a map of the circumpolar region, which is in full view every clear night. It revolves daily round Polaris, its central point. Toward this star, the two end stars of the Great Dipper ever point, and are in consequence called "the Pointers." The map may be held toward the northern sky in such a position as the stars may happen to be. The Great Bear, or Dipper, will be seen at nine o'clock in the evening above the pole in April and May ; west of the pole, the Pointers downward, in July and August ; close to the north ho- rizon in October and November; and east of the pole the Pointers highest, in January and .February. The names of such constantly visible stars should be familiar. In order, from the end of the tail of the Great Bear, we have Beuetnasch ij, Mizar , Little Alcor close to it, Ali- 198 THE STELLAR SYSTEM. oth e, Megrez S, at the junction, has been growing dim- mer for a century, Phad 7, Dubhe and Merak. It is best to get some facility at estimating distances in de- grees. Dubhe and Merak, " the Pointers," are five de- grees apart. Eighteen degrees forward of Dubhe is the Bear's nose ; and three pairs of stars, fifteen degrees apart, show the position of the Bear's three feet. Fol- low "the Pointers" twenty-nine degrees from Dubhe, and we come to the pole-star. This star is double, made of two suns, both appearing as one to the naked eye. It is a test of an excellent three-inch telescope to resolve it into two. Three stars beside it make the curved-up handle of the Little Dipper of Ursa Minor. Between the two Bears, thirteen degrees from Megrez, and eleven degrees from Mizar, are two stars in the tail of the Dragon, which curves about to appropriate all the stars not otherwise assigned. Follow a curve of fifteen stars, doubling back to a quadrangle from five to three de- grees on a side, and thirty-five degrees from the pole, for his head. His tongue runs out to a star four degrees in front. We shall find, hereafter, that the foot of Her- cules stands on this head. This is the Dragon slain by Cadmus, and whose teeth produced such a crop of san- guinary men. The star Thuban was once the pole-star. In the year B.C. 2300 it was ten times nearer the pole than Polaris is now. In the year A.D. 2100 the pole will be within 30' of Polaris ; in A.D. 7500, it will be at a of Cepheus ; in A.D. 13,500, within 7 of Vega ; in A.D. 15,700, at the star in the tongue of Draco ; in A.D. 23,000, at Thuban ; in A.D. 28,000, back to Polaris. This indicates no change in the position of the dome THE OPEN PAGE OF THE HEAVENS. 199 of stars, but a change iu the direction of the axis of the earth pointing to these various places as the cy- cles pass. As the earth goes round its orbit, the axis, maintaining nearly the same direction, really points to every part of a circle near the north star as large as the earth's orbit, that is, 185,000,000 miles in diameter. But, as already shown, that circle is too small to be discerni- ble at our distance. The wide circle of the pole through the ages is really made up of the interlaced curves of the annual curves continued through 25,870 years. The stem of the spinning top wavers, describes a circle, and finally falls ; the axis of the spinning earth wavers, describes a circle of nearly 26,000 years, and never falls. The star y Draconis, also called Etanin, is famous in modern astronomy, because observations on this star led to the discovery of the aberration of light. If we held a glass tube perpendicularly out of the window of a car at rest, when the rain was falling straight down, we could see the drops pass directly through. Put the car in motion, and the drops would seem to start toward us, and the top of the tube must be bent forward, or the drops entering would strike on the backside of the tube carried toward them. So our telescopes are bent forward on the moving earth, to enable the entered light to reach the eye-piece. Hence the star does not appear just where it is. As the earth moves faster in some parts of its orbit than others, this aberration is sometimes greater than at others. It is fortunate that light moves with a uniform velocity, or this difficult problem would be still further complicated. The dis- placement of a star from this cause is about 20". 43, 200 THE STELLAR SYSTEM. On the side of Polaris, opposite to Ursa Major, is King Cephens, made of a few dim stars in the form of the letter K. Near by is his brilliant wife Cassiopeia, sitting on her throne of state. They were the grace- less parents who chained their daughter to a rock for the sea-monster to devour ; but Perseus, swift with the winged sandals of Mercury, terrible with his avenging sword, and invincible with the severed head of Me- dusa, whose horrid aspect of snaky hair and scaly body turned to stone every beholder, rescues the maiden from chains, and leads her away by the bands of love. Noth- ing could be more poetical than the life of Perseus. When he went to destroy the dreadful Gorgon, Medusa, Pluto lent him his helmet, which would make him in- visible at will ; Minerva loaned her buckler, impenetra- ble, and polished like a mirror; Mercury gave him a dagger of diamonds, and his winged sandals, which would carry him through the air. Coming to the loathsome thing, he would not look upon her, lest he, too, be turned to stone ; but, guided by the reflection in the buckler, smote off her head, carried it high over Libya, the dropping blood turning to serpents, which have infested those deserts ever since. The human mind has always been ready to deify and throne in the skies the heroes that labor for others. Both Perseus and Hercules are divine by one parent, and human by the other. They go up and down the earth, giving deliverance to captives, and breaking ev- ery yoke. They also seek to purge away all evil ; they slay dragons, gorgons, devouring monsters, cleanse the foul places of earth, and one of them so wrestles with death as to wjn a victim from his grasp. Finally, bv CIRCUMPOLAR CONSTELLATIONS. 201 Fig. 6T Circumpolar Constellations. Always visible. In this position Janu- ary 20th, at 10 o'clock; February 4th, at 9 o'clock; and February 19th, at 8 o'clock. an ascension in light, they go up to be in light forever. They are not ideally perfect. They right wrong by slaying wrong -doers, rather than by being crucified themselves; they are just murderers; but that only plucks the fruit from the tree of evil. They never attempted to infuse a holy life. They punished rather than regenerated. It must be confessed, also, that they were not sinless. But they were the best saviors the race could imagine, and are examples of that perpetual effort of the human mind to incarnate a Divine Helper who shall labor and die for the good of men. THE STELLAR SYtiTJt'M. Fig. 6S Algol is oil the Meridian, 51 Soulh of Pole. At 10 o'clock, Decembei Tth ; 9 o'clock, December 22d ; 8 o'clock, January 5th. Equatorial Constellations. If we turn our backs on Polaris on the 10th of No- vember, at 10 o'clock in the evening, and look directly overhead, we shall see the beautiful constellation of Andromeda. Together with the square of Pegasus, it makes another enormous dipper. The star a Alpheratz is in her face, the three at the left cross her breast. |3 and the two above mark the girdle of her loins, and y is in the foot. Perseus is near enough for help ; and Cetns, the sea-monster, is far enough away to do no harm. Below, and east of Andromeda, is the Ram of the golden fleece, recognizable by the three stars in an acute triangle. The brightest is called Arietis, or Hamel. East of this are the Pleiades, and the V-shaped Hyades in Taurus, or the Bull. The Pleiades rise about 9 o'clock on the evening of the 10th of September, and at 3 o'clock A.M. on June 10th. EQUATORIAL CONSTELLATIONS. 203 Fig. 69. Capella (45 from the Pole) aud Rigel (100) are on the Meridian at 8 o'clock February Tth, 9 o'clock January 22d, and at 10 o'clock January 7th. Fig. 69 extends east and south of our last map. It is the most gorgeous section of our heavens. (See the Notes to the Frontispiece.) Note the triangle, 26 on a side, made by Betelguese, Sirins, and Procyon. A line from Procyon to Pollux leads quite near to Polaris. Orion is the mighty hunter. Under his feet is a hare, behind him are two dogs, and before him is the rushing bull. The curve of stars to the right of Bellatrix, 7, represents his shield of the Nemean lion's hide. The three stars of his belt make a measure 3 long ; the upper one, Mintaka, is less than 30' south of the equi- noctial. The ecliptic passes between Aldebaran and the Pleiades. Sirius rises about 9 o'clock P.M. on the 1st of December, and about 4 o'clock A.M. on the 16th of Au- gust. Procyon rises about half an hour earlier. 204 THE STELLAR SYSTEM. Fig. 70. Regnlns comes on the Meridian, 79 sonth from the Pole, at 10 o'clock March 23d, 9 o'clock April 8th, and at 8 o'clock April 28d. Fig. 70 continues eastward. Note the sickle in the head and neck of the Lion. The star /3 is Denebola, in his tail. Arcturus appears by the word Bootes, at the edge of the map. These two stars make a triangle with Spica, about 35 on a side. The geometric head of Hydra is easily discernible east of Procyon. The star y in the Virgin is double, with a period of 145 years. is just above the equinoctial. There is a fine nebula two-thirds of the way from 8 to j, and a little above the line connecting the two. Coma Berenices is a beauti- ful cluster of faint stars. Spica rises at 9 o'clock on the 10th of February, at 5 o'clock A.M. on the 6th of November. EQUATORIAL CONSTELLATIONS. 205 Fig. il. Arcturus comes to the Meridian, 70 from the Pole, at 10 o'clock May 25th, 9 o'clock Juue 9th, and at 8 o'clock Jane 26th. Fig. 71 represents the sky to the eastward and north- ward of the last. A line drawn from Polaris and Benetnasch comes east of Arcturus to the little triangle called his sons. Bootes drives the Great Bear round the pole. Arcturus and Denebola make a triangle with a, also called Cor Cceroli, in the Hunting Dogs. This triangle, and the one having the same base, with Spica for its apex, is called the "Diamond of the Virgin." Hercules appears head down a in the face, /3, 7, S in his shoulders, IT and >j in the loins, r in the knee, the foot being bent to the stars at the right. The Serpent's head, making an x , is just at the right of the y of Hercules, and the partial circle of the Northern Crown above. The head of Draco is seen at /3 on the left of the map. Arcturus rises at 9 o'clock about the 20th of February, and at 5 A.M. on the 22d of October ; Kegu- lus 3h. 35m. earlier. 206 THE STELLAR SYSTEM. ' Fig. 72. Altair comes to the Meridian, 82 from the Pole, at 10 o'clock i-.si. Au- gust 18th, at 9 o'clock September 2d, and at 8 o'clock September ISth. Fig. 72 portrays the stars eastward and southward. Scorpio is one of the most brilliant and easily traced constellations. Antares, a, in the heart, is double. In Sagittarius is the Little Milk-dipper, and west of it the bended bow. Vega is at the top of the map. Near it observe , a double, and E, a quadruple star. The point to which the solar system is tending is marked by the sign of the earth below TT Herculis. The Serpent, west of Hercules, and coiled round nearly to Aquila, is very traceable. In the right-hand lower corner is the Cen- taur. Below, and always out of our sight, is the famous a Centauri. The diamond form of the Dolphin is some- times called " Job's Coffin.'' The ecliptic passes close BQ UA TORIAL CONSTELLA TIONS. Fig. 73. Fomulhaut couies to the Meridian, only 17 from the horizon, at 8 o'clock November 4th. to j3 of Scorpio, which star is in the head. Antares, in Scorpio, rises at 9 o'clock P.M. on May 9th, and at 5 o'clock A.M. on January 5th. In Fig. 73 we recognize the familiar stars of Pegasus, which tell us we have gone quite round the heavens. Note the beautiful cross in the Swan. /3 in the bill is named Albireo, and is a beautiful double to almost any glass. Its yellow and blue colors are very distinct. The place of the famous double star 61 Cygni is seen. The first magnitude star in the lower left-hand corner is Fomalhaut, in the Southern Fish, a Pegasi is in the diagonal corner from Alpheratz, in Andromeda. The star below Altair is /3 Aquilae, and is called Alschain ; the one above is y Aquilae, named Tarazed. This is not a brilliant section of the sky. Altair rises at 9 o'clock on the 29th of May, and at 6 o'clock A.M. on the llth of January. 208 THE STELLAR SYSTEM. Fig. 74. Southern Circumpular Constellations invisible north of ilie Equator. Fig. 74: gives the stars that are best seen by per- sons south of the earth's equator. In the ship is brill- iant Canopus, and the remarkable variable ?j. Below it is the beautiful Southern Cross, near the pole of the southern heavens. Just below are the two first mag- nitude stars Bungiila, a, and Achernar, /3, of the Centaur. Such a number of unusually brilliant stars give the southern sky an unequalled splendor. In the midst of them, as if for contrast, is the dark hole, called by the sailors the "Coal -sack," where even the telescope re- veals no sign of light. Here, also, are the two Magel- lanic clouds, both easily discernible by the naked eye ; the larger two hundred times the apparent size of the moon, lying between the pole and Canopus, and the other between Achernar and the pole. The smaller cloud is only one-fourth the size of the other. Both are mostly resolvable into groups of stars from the fifth to the fifteenth magnitude. CHARACTERISTICS OF THE STARS. 209 For easy out-door finding of the stars above the hori- zon at any time, see star-maps at end of the book. Characteristics of the Stars. Such a superficial examination of stars as we have made scarcely touches the subject. It is as the study of the baptismal register, where the names were an- ciently recorded, without any knowledge of individuals. The heavens signify much more to us than to the Greeks. We revolve under a dome that investigation has infinitely enlarged from their estimate. Their lit- tle lights were turned by clumsy machinery, held to- gether by material connections. Our vast worlds are connected by a force so fine that it seems to pass out of the realm of the material into that of the spiritual. Animal ferocity or a human Hercules could image their idea of power. Ours finds no symbol, but rises to the Almighty. Their heavens were full of fighting Orions, wild bulls, chained Andromedas, and devouring mon- sters. Our heavens are significant of harmony and unity ; all worlds carried by one force, and all harmo- nized into perfect music. All their voices blend their various significations into a personal speaking, which says, " Hast thou not heard that the everlasting God, the Lord, the creator of the ends of the earth, fainteth not, neither is weary ?" There is no searching of his understanding. Lift up your eyes on high, and behold who hath created all these things, that brought out their host by number, that calleth them all by their names in the greatness of his power; for that he is strong in power not one faileth. 210 THE STELLAR SYSTEM. Number. We find about five thousand stars visible to the naked eye in the whole heavens, both north and south. Of these twenty are of the first magnitude, sixty -five of the second, two hundred of the third, four hundred of the fourth, eleven hundred of the fifth, and three thousand two hundred of the sixth. We think we can easily number the stars; but train a six-inch telescope on a little section of the Twins, where six faint stars are visible, and over three thousand luminous points appear. The seventh magnitude has 13,000 stars; the eighth, 40,000 ; the ninth, 142,000. There are 18,000,000 stars in the zone called the Milky Way. When our eyes are not sensitive enough to be affected by the light of far- off stars the tasimeter feels their heat, and tells us the word of their Maker is true " they are innumerable."* Double and Multiple Stars. If we look up during the summer months nearly over- head at the star e Lyne, east of Vega (Fig. 72), we shall see with the naked eye that the star appears a little * Telescopic Work. Look at the Hyades and Pleiades in Taurus. Notice the different colors of stars in them both. Find the cluster Praesepe in Fig. 70, just a trifle above a point midway betweea Procyon and Regulus. It is equally distant from Procyon and a point a little below Pollux. Sweep along the Milky Way almost anywhere, and ob- serve the distribution of stars ; in some places perfect crowds, in oth- ers more sparsely scattered. Find with the naked eye the ricli cluster in Perseus. Draw a line from Algol to a of Perseus (Fig. 67) ; turn at right angles to the right, at a distance of once and four-tenths the first line a brightness will be seen, The telescope reveals u gorgeous cluster. DOUBLE AND MULTIPLE STARS. 211 elongated. Turn your opera -glass upon it, and two stars appear. Turn a larger telescope on this double star, and each of the components separate into two. It is a double double star. We know that if two stars are near in reality, and not simply apparently so by being in the same line of sight, they must revolve around a common centre of gravity, or rush to a common ruin. Eagerly we watch to see if they revolve. A few years suffice to show them in actual revolution. Nay, the movement of revolution has been decided before the companion star was discovered. Sirius has long been known to have a proper motion, such as it would have if another sun were revolving about it. Even the di- rection of the unseen body could always be indicated. In February, 1862, Alvan Clark, artist, poet, and maker of telescopes (which requires even greater genius than to be both poet and artist), discovered the companion of Sirins just in its predicted place. As a matter of fact, one of Mr. Clark's sons saw it first ; but their fame is one. The time of revolution of this pair is fifty years. But one companion does not meet the conditions of the movements. Here must also be one or more planets too small or dark to be seen. The double star in the Great Bear (see Fig. 70) makes a revolution in fifty- eight years. Procyon moves in an orbit which requires the pres- ence of a companion star, but it has as yet eluded our search. Castor is a double star; but a third star or planet, as yet undiscovered, is required to account for its perturbations. Men who discovered Neptune by the perturbations of Uranus are capable of judging the ca.use of the perturbations of suns. We have spoken of 212 THE STELLAR SYSTEM. the whole orbit of the earth being invisible from the stars. The nearest star in our northern hemisphere, 61 Cygni, is a telescopic double star ; the constituent parts of it are forty-five times as far from each other as the earth is from the sun, yet it takes a large opera-glass to show any distance between the stars.* When -y Virginis was observed in 1718 by Bradley, the component parts were 1" asunder. He incidental- ly remarked in his note -book that the line of their connection was parallel to the line of the two stars Spica, or a and <$ Virginis. By 1840 they were not more than 1" apart, and the line of their connection greatly changed. The appearance of the star is given in Fig. 75 (15), commencing at the left, for the years 1837, '38, '39, '40, '45, '50, '60, and '79 ; also a con- jectural orbit, placed obliquely, and the position of * Telescopic Work. Only such work will be laid out here as can be done by small telescopes of from two to four inch object-glasses. The numbers in Fig. 75 correspond to those of the table. No. Name. Fig. Dist. of Parts. Magni- tudes. Remarks. 1. t Lyrae.... 72 I' 56" Quadruple. 2. SLyra... 72 44 5 and 6 Topaz and green. 3. /3 Cvgni.. 73 34 3 " 6 Yellow and blue. 4. 61 Cygni. 73 20 5 " 6 Nearest star but one. 5. Mizar 67 14 3 " 4 Both white. 6. Polaris... 67 18* 2 " 9 jTest object of eye ( and glass. 7. p Orionis. Frontispiece. 7 5 " 8 Yellow and blue. 8. ft Orionis. ' 9 1 " 8 Rigel. 9. S " . " 10 2 " 8 Red and white. 10. " . ii Septuple. 11. X " . " 5 White and violet. 12. v " " A,B. 11 4 ""'JO Octuple. 13. Castor.... 69 5 * 2 " 3 White. 14. 15. Pollux.... y Virginis. 69 70 5 Triple. 3 and 3 Orange, gray, lilac. Both yellow". DOUBLE AND MULTIPLE STARS. 213 the stars at the times mentioned, commencing at the top. The time of its complete revolution is one hun- dred and fifty years. Pig. 75. Aspects and Revolution of Double Stars. The meaning of these double stars is that two or more suns revolve about their centre of gravity, as the rnoon and earth about their centre. If they have plan- ets, as doubtless they have, the movement is no more complicated than the planets we call satellites of Saturn revolving about their central body, and also about the sun. Kindle Saturn and Jupiter to a blaze, or let out their possible light, and our system would appear a triple star in the distance. Doubtless, in the far past, before these giant planets were cooled, it so appeared. We find some stars double, others triple, quadruple, octuple, and multiple. It is an extension of the same principles that govern our system. Some of these suns are so far asunder that they can swing their Neptunes between them, with less perturbation than Uranus and Neptune have in ours. Light all our planets, and there would be a multiple star with more or less suns seen, '214 Tti STELLAR SYSTEM. according to the power of the instrument. Perhaps the octuple star a in Orion differs in no respect from our sys- tem, except in the size and distance of its separate bod- ies, and less cooling, either from being younger, or from the larger bodies cooling more slowly. Suns are of all ages. Infinite variety fills the sky. It is as preposter- ous to expect that every system or world should have analogous circumstances to ours at the present time, as to insist that every member of a family should be of the same age, and in the same state of development. There are worlds that have not yet reached the conditions of habitability by men, and worlds that have passed these conditions long since. Let them go. There are enough left, and an infinite number in the course of preparation. Some are fine and lasting enough to be eternal mansions. Colored Stars. In the smoky morning we get only red light, but the sun is white. So Aldebaran and Betelguese may be girt by vapors, that only the strong red rays can pass. Again, an iron moderately heated gives out dull red light ; becoming hotter, it emits white light. Sirins, Regulus, Vega, and Spica may be white from greater intensity of vibration. Procyon, Capella, and Polaris are yellow from less intensity of vibration. Again, burn salt in a white flame, and it turns to yellow ; mix alcohol and boracic acid, ignite them, and a beautiful green flame results; alcohol and nitrate of strontia give red flame ; alcohol and nitrate of barytes give yellow flame. So the composition of a sun, or the spe- cial development of any one substance thereof at any time, may determine the color of a star. CLUSTERS OF STARS. 215 The special glory of color in the stars is seen in the marked contrasts presented in the double and multiple stars. The larger star is usually white, still in the in- tensity of heat and vibration ; the others, smaller, are somewhat cooled off, and hence present colors lower down the scale of vibration, as green, yellow, orange, and even red. That stars should change color is most natural. Many causes -would produce this effect. The ancients said Si- rius was red. It is now white. The change that would most naturally follow mere age and cooling would be from white, through various colors, to red. We are charmed with the variegated flowers of our gardens of earth, but he who makes the fields blush with flowers under the warm kisses of the sun has planted his wider gardens of space with colored stars. " The rainbow flowers of the footstool, and the starry flowers of the throne," proclaim one being as the author of them all. Clusters of Stars. From double and multiple we naturally come to groups and clusters. Allusion has been made to the Hyades, Pleiades, etc. Every one has noticed the Milky "Way. It seems like two irregular streams of compacted stars. It is not supposed that they are nec- essarily nearer together than the stars in the sparse re- gions about the pole. But the 18,000,000 suns belong- ing to our system are arranged within a space repre- sented by a flattened disk. If one hundred lights, three inches apart, are arranged on a hoop ten feet in diame- ter, they would be in a circle. Add a thousand or two more the same distance apart, filling up the centre, and 216 THE STELLAR SYSTEM. 76. Sprayed Cluster below rj in Hercules. extending a few inches on each side of the inner plane of the hoop : an eye in the centre, looking out toward the edge, would see a milky way of lights ; looking out toward the sides or poles, would see comparatively few. It would seem as if this oblate spheroidal ar- rangement was the result of a revolution of all the suns composing the system. Jupiter and earth are flat- tened at the poles for the same reason. In various parts of the heavens there are small globular well-defined clus- ters, and clusters very irregular in form, marked with sprays of stars. There is a cluster of this latter class in Hercules, just under the S, in Fig. 72. " Probably no one ever saw it with a good telescope without a shout of wonder." Here is a cluster of the former class represented in Fig. 77. " The noble globular clus- ter a) Centauri is beyond all comparison the richest and largest object of the kind Fig ' 77 - Glubular Clnster - in the heavens. Its stars are literally innumerable ; and as their total light, when received by the naked eye, af- fects it hardly more than a star of the fifth to fourth NEBULAE. 217 magnitude, the minuteness of each star may be imag- ined." There are two possibilities of thought concerning these clusters. Either that they belong to our stellar system, and hence the stars must be small and young, or they are another universe of millions of suns, so far away that the inconceivable distances between the stars are shrunken to a hand's-breadth, and their unbearable splendor of innumerable suns can only make a gray haze at the distance at which we behold them. The latter is the older and grander thought ; the former the newer and better substantiated. Nebula. The gorgeous clusters we have been considering ap- pear to the eye or the small telescope as little cloudlets of hazy light. One after another were resolved into stars ; and the natural conclusion was, that all would yield and reveal themselves to be clustered suns, when we had telescopes of sufficient power. But the spec- troscope, seeing not merely form but substance also, shows that some of them are not stars in any sense, but masses of glowing gas. Two of these nebulae are visi- ble to the naked eye : one in Andromeda (see Fig. 68), and one around the middle star of the sword of Orion, shown in Fig. 78. A three -inch telescope resolves 9 Orionis into the famous trapezium, and a five-inch in- strument sees two stars more. The shape of the nebula is changeable, and is hardly suggestive of the moulding influence of gravitation. It if, probably composed of glowing nitrogen and hydrogen gases. Nebulae are of all conceivable shapes circular, annular, oval, lenticu- 10 218 THE STELLAR SYSTEM. lar, conical, spiral, snake -like, looped, and nameless. Compare the sprays of the Crab nebulae above Tauri, Fig. 78. The great Nebula about the multiple Star Oriouis. (See Frontispiece.) seen in Fig. 79, and the ring nebula, Fig. 80. This last possibly consists of stars, and is situated, as shown in Fig. 81, midway between /3 and 7 Lyras. When Herschel was sweeping the heavens with his telescope, and saw but few stars, he often said to his assistant, " Prepare to write ; the nebulae are coming." They are most abundant where the stars are least so. A zone about the heavens 30 wide, with the Milky Way in the centre, would include one-fourth of the ce- lestial sphere ; but instead of one-fourth, we find nine- NEBULA. 219 tenths of the stars in this zone, and but one-tenth of the nebulse. These immense masses of unorganized matter are noticed to change their forms, vary their light greatly, but not quickly ; they change through the ages. " God works slowly." He takes a thousand years to lift his hand off. Fig. 79. Crab Nebula, near Tauri. (SVM Frontispiece.) There are many unsolved problems connected with these strange bodies. Whether they belong to our sys- tem, or are beyond it, is not settled ; the weight of evi- dence leans to the first view. 220 THE STELLAR SYSTEM. Variable Stars. Our sun gives a variable amount of light, changing through a period of eleven years. Probably every star, Fig. 80. The Ring Nebnla. ii examined by methods sufficiently delicate and exact, would be found to be variable. The variations of some VARIABLE STARS. 221 stars are so marked as to challenge investigation. /3 Lyrae (Fig. 81) has two maxima and minima of light. In Fig. 81. Constellation Lyra, showing place of the Ring Nebula. three days it rises from magnitude 4 to 3 ; in a week it falls to 4, and rises to 3 ; and in three days more drops to 4: it makes all these changes in thirteen days; but this period is constantly increasing. The variations of one hundred and forty -three stars have been well ascertained. Mira, or the Wonderful, in the Whale (Fig. 68), is easily found when visible. Align from Capella to the Pleiades, and as much farther, and four stars will be seen, situated thus: * * * The right-hand one is Mira. For half a month it shines as a star of the second magnitude. Then for three months it fades away, and is lost to sight ; going down even to the eleventh mag- nitude. Bat after five months its resurrection morning comes; and in three months more eleven months in all our Wonderful is in its full glory in the heavens. But its period and brilliancy are also variable. The star Megrez, 8 in the Great Bear, has been growing dim 222 THE STELLAR SYSTEM. for a century. In 1836 Betelguese was exceedingly variable, and continued so till 1840, when the changes became much less conspicuous. Algol (Fig. 68) has been already referred to. This slowly winking eye is of the second magnitude during 2d. 14h. Then it dozes off toward sleep for 4h. 24m., when it is nearly invisible. It wakes up during the same time; so that its period from maximum brilliancy to the same state again is 2d. 20h. 48m. Its recognizable changes are within five or six hours. As I write, March 25th, 1879, Algol gives its minimum light at 9h. 36m. P.M. It passes fifteen minima in 43d. 13m. There will therefore be another minimum May 7th, at 9h. 49m. Its future periods are easy to estimate. Perhaps it has some dark body revolving about it at frightful speed, in a period of less than three days. The period of its variability is growing shorter at an increasing rate. If its variability is caused by a dark body revolving about it, the orbit of that body is contracting, and the huge satellite will soon, as celestial periods are reckoned, commence to graze the surface of the sun itself, rebound again and again, and at length plunge itself into the central fire. Such an event would evolve heat enough to make Algol flame up into a star of the first magnitude, and perhaps out^ blaze Sirius or Capella in our winter sky. None of the causes for these changes we have been able to conjecture seem very satisfactory. The stars may have opaque planets revolving about them, shut- ting off their light ; they may rotate, and have unequal- ly illuminated sides; they may revolve in very elliptical orbits, so as to greatly alter their distance from us ; they may be so situated in regard to zones of meteorites as TEMPORARY, NEW, AND LOST STARS. 223 to call down periodically vast showers ; but none or all of these suppositions apply to all cases, if they do to any. Temporary, New, and Lost Stars. Besides regular movements to right and left, up and down, to and from us changes in the intensity of illu- mination by changes of distance besides variations oc- curring at regular and ascertainable intervals, there are stars called temporary, shining awhile and then disap- pearing ; new, coming to a definite brightness, and BO remaining ; and lost, those whose first appearance was not observed, but which have utterly disappeared. In November, 1572, a new star blazed out in Cassio- peia. Its place is shown in Fig. 67, \ y being the stars S * in the seat of the chair, and being the first one ? * in the back. This star was visible at noonday, and was brighter than any other star in the heavens. In January, 1573, it was less bright than Jupiter ; in April it was below the second magnitude, and the last of May it utterly disappeared. It was as variable in color as in brilliancy. During its first two months, the period of greatest brightness, it was dazzling white, then became yellow, and finally as red as Mars or Aldebaran, and so expired. A bright star was seen very near to the place of the Pilgrim, as the star of 1572 was called, in A.D. 945 and 1264. A star of the tenth magnitude is now seen brightening slowly almost exactly in the same place. It is possible that this is a variable star of a period of about three hundred and ten years, and will blaze out again about 1885. But we have had, within a few years, fine opportuni- 224: THE STELLAR SYSTEM. ties to study, with improved instruments, two new stars. On the evening of May 12th, 1866, a star of the second magnitude was observed in the Northern Crown, where no star above the fifth magnitude had been twenty- four hours before. In Argelander's chart a star of the tenth magnitude occupies the place. May 13th it had declined to the third magnitude, May 16th to the fourth, May 17th to the fifth, May 19th to the seventh, May 31st to the ninth, and has since diminished to the tenth. The spectroscope showed it to be a star in the usual condition ; but through the usual colored spectrum, crossed with bright lines, shone four bright lines, two of which indicated glowing hydrogen. Here was plen- ty of proof that an unusual amount of this gas had given this sun its sudden flame. As the hydrogen burned out the star grew dim. Two theories immediately presented themselves: First, that vast volumes had been liberated from within the orb by some sudden breaking up of the doors of its great deeps; or, second, this star had precipitated upon itself, by attraction, some other sun or planet, the force of whose impact had been changed into heat. Though we see the liberated hydrogen of our sun burst up with sudden flame, it can hardly be supposed that enough could be liberated at once to increase the light and heat one hundred-fold. In regard to the second theory, it is capable of proof that two suns half as large as ours, moving at a velocity of four hundred and seventy-six miles per second, would evolve heat enough to supply the radiation of our sun for fifty million years. How could it be possible for a sun like this newly blazing orb to cool off to such a TEMPORARY, NEW, AND LOST STARS. 225 degree in a month ? Besides, there would not be one chance in a thousand for two orbs to come directly to- gether. They would revolve about each other till a kind of grazing contact of grinding worlds would slow- ly kindle the ultimate heat. It is far more likely that this star encountered an enormous stream of meteoric bodies, or perhaps absorb- ed a whole comet, that laid its million leagues of tail as fuel on the central tire. Only let it be remembered that the fuel is far more force than substance. Allu- sion has already been made to the sudden brightening of our sun on the first day of September, 1859. That was caused, no doubt, by the fall of large meteors, fol- lowing in the train of the comet of 1843, or some other comet. What the effect would have been, had the whole mass of the comet been absorbed, cannot be imagined. Another new star lately appeared in Cygnus, near the famous star 61 the first star in the northern hem- isphere whose distance was determined. It was first seen November 24th, 1876, as a third magnitude star of a yellow color. By December 2d it had sunk to the fourth magnitude, and changed to a greenish color. It had then three bright hydrogen lines, the strong double sodium line, and others, which made it strongly resem- ble the spectrum of the chromosphere of our sun. An entirely different result appeared in the fading of these two stars. In the case of the star in the Crown, the ex- traordinary light was the first to fade, leaving the usual stellar spectrum. In the case of the star in Cygnus, the part of the spectrum belonging to stellar light was the first to fade, leaving the bright lines ; that is, the gas of one gave way to regular starlight, and the starlight 10* 226 THE STELLAR SYSTEM. of the other having faded, the regular light of the glow- ing gas continued. By some strange oversight, no one studied the star again for six months. In September and November, 1877, the light of this star was found to be blue, and not to be starlight at all. It had no rain- bow spectrum, only one kind of rays, and hence only one color. Its sole spectroscopic line is believed to be that of glowing nitrogen gas. We have then, probably, in the star of 1876, a body shining by a feeble and un- discernible light, surrounded by a discernible immensi- ty of light of nitrogen gas. This is its usual condition; but if a flight of meteors should raise the heat of the central body so as to outshine the nebulous envelope, we should have the conditions we discovered in No- vember, 1876. But a rapid cooling dissipates the ob- servable light of all colors, and leaves only the glowing gas of one color. Movements of Stars. We call the stars fixed, but motion and life are nec- essary to all things. Besides the motion in the line of sight described already, there is motion in every other conceivable direction. We knew Sirius moved before we had found the cause. We know that our sun moves back and forth in his easy bed one-half his vast diam- eter, as the larger planets combine their influence on one side or the other. The sun has another movement. We find the stars in Hercules gradually spreading from each other. Her- cules's brawny limbs grow brawnier every century. There can be but one cause : we are approaching that quarter of the heavens. (See , Fig. 72.) We are even MOVEMENTS OF STARS. 227 able to compute the velocity of our approach ; it is eight miles a second. The stars in the opposite quarter of the heavens in the Dove are drawing nearer together. This movement would have no effect on the apparent place of the stars at either pole, if they were all equally distant ; but it must greatly extend or contract the ap- parent space between them, since they are situated at various distances. Independent of this, the stars themselves are all io motion, but so vast is the distance from which we ob- serve them that it has taken an accumulation of centu- ries before they could be made measurable. A train going forty miles an hour, seen from a distance of two miles, almost seems to stand still. Arcturus moves through space three times as fast as the earth, but it takes a century to appear to move the eighth part of the diameter of the moon. There is a star in the Hunt- ing Dogs, known as 1830 Groombridge, which has a velocity beyond what all the attraction of the matter of the known universe could give it. By the year 9000 it may be in Berenice's Hair. Some stars have a common movement, being evident- ly related together. A large proportion of the bright- er stars between Aldebaran and the Pleiades have a common motion eastward of about ten seconds a cen- tury. All the angles marked by a, /3, 7, \ Orionis will be altered in different directions; X is moving toward y. A and t will appear as a double star. In A.D. 50,000 Procyon will be nearer % Orionis than Kigel now is, and Sirius will be in line with a and x Orionis. All the stars of the Great Dipper, except Benetnasch and Dubhe, have a common motion somewhat in the direc- 228 THE STELLAk SYSTEM. tion of Thuban (Fig. 67), while the two named have a motion nearly opposite. In 36,000 years the end of the Dipper will have fallen out so that it will hold no water, arid the handle will be broken square off at Mi- zar. " The Southern Cross," says Humboldt, " will not always keep its characteristic form, for its four stars travel in different directions with unequal velocities. At the present time it is not known how many myriads of years must elapse before its entire dislocation." These movements are not in fortuitous or chaotic ways, but are doubtless in accordance with some perfect plan. We have climbed up from revolving earth and moon to revolving planets and sun, in order to under- stand how two or ten suns can revolve about a common centre. Let us now leap to the grander idea that all the innumerable stars of a winter night not only can, but must revolve about some centre of gravity. Men have been looking for a central sun of suns, and have not found it. None is needed. Two suns can balance about a point ; all suns can swing about a common centre. That one unmoving centre may be that city more gorgeous than Eastern imagination ever conceived, whose pavement is transparent gold, whose walls are precious stones, whose light is life, and where no dark planetary bodies ever cast shadows. There reigns the King and Lord of all, and ranged about are the far- off provinces of his material systems. They all move in his sight, and receive power from a mind that never wearies. XI. THE WORLDS AND THE WORD. Tbe worlds were framed by the word of God." Heb. xi., 3 " Mysterious night! when our first parent knew thee From report divine, and heard thy name, Did he not tremble for this lovely frame, This glorious canopy of light and blue ? Yet, 'neath a curtain of translucent dew, Bathed in the rays of the great setting flauie, Hesperus, with all the host of heaven, came, And lo ! creation widened in man's view. Who could have thought such darkness lay concealed Within thy beams, O Sur. ! Oh who could find, Whilst fruit and leaf and insect stood revealed, That to such countless worlds thou mad'st us blind ! Why do we then shun death with anxious strife ? If light conceal so much, wherefore not life ?" BLANCO WHITE TUB WORLDS AND THE WORD. 231 XI. THE WORLDS AND THE WORD. MEN have found the various worlds to be far rich- er than they originally thought. They have opened door after door in their vast treasuries, have ascended throne after throne of power, and ruled realms of in- creasing extent. We have no doubt that unfoldings in the future will amaze even those whose expectations have been quickened by the revealings of the past. What if it be found that the Word is equally inex- haustible? After ages of thought and discovery we have come out of the darkness and misconceptions of men. We believe in no serpent, turtle, or elephant supporting the world; no Atlas holding up the heavens; no crys- tal domes, " with cycles and epicycles scribbled o'er." What if it be found that one book, written by ignorant men, never fell into these mistakes of the wisest ! Nay, more, what if some of the greatest triumphs of modern science are to be found plainly stated in a book older than the writings of Homer? If suns, planets, and satellites, with all their possibilities of life, changes of flora and fauna, could be all provided for, as some scientists tell us, in the fiery star-dust of a cloud, why may not the same Author provide a perpetually widen- ing river of life in his Word? As we believe He is perpetually present in his worlds, we know He has 232 THE WOJtLDS AND THE WORD. promised to be perpetually present in his Word, making it alive with spirit and life. The wise men of the past could not avoid alluding to ideas the falsity of which subsequent discovery has revealed ; but the writers of the Bible did avoid such erroneous allusion. Of course they referred to some things, as sunrise and sunset, according to appearance ; but our most scientific books do the same to-day. That the Bible could avoid teaching the opposite of scientific truth proclaims that a higher than human wisdom was in its teaching. That negative argument is strong, but the affirmative argument is much stronger. The Bible declares scien- tific truth far in advance of its discovery, far in ad- vance of man's ability to understand its plain declara- tions. Take a few conspicuous illustrations: The Bible asserted from the first that the present order of things had a beginning. After ages of investi- gation, after researches in the realms of physics, argu- ments in metaphysics, and conclusions by the necessities of resistless logic, science has reached the same result. The Bible asserted from the first that creation of matter preceded arrangement. It was chaos void without form darkness: arrangement was a subsequent work. The world was not created in the form it was to have ; it was to be moulded, shaped, stratified, coal- ed, mountained, valleyed, subsequently. All of which science utters ages afterward. The Bible did not hesitate to affirm that light existed before the sun, though men did not believe it, and used it as a weapon against inspiration. Now we praise men for having demonstrated the oldest record. THE WORLDS AND THE WORD. 233 It is a recently discovered truth of science that the strata of the earth were formed by the action of water, and the mountains were once under the ocean. It is an idea long familiar to Bible readers : " Thou coverest the earth with the deep as with a garment. The waters stood above the mountains. At thy rebuke they fled ; at the voice of thy thunder they hasted away. The mountains ascend; the valleys descend into the place thou hast founded for them." Here is a whole volume of geology in a paragraph. The thunder of continental convulsions is God's voice; the mountains rise by God's power ; the waters haste away unto the place God pre- pared for them. Our slowness of geological discovery is perfectly accounted for by Peter. " For of this they are willingly ignorant, that by the word of God there were heavens of old, and land framed out of water, and by means of water, whereby the world that then was, being overflowed by water, perished." We recog- nize these geological subsidences, but we read them from the testimony of the rocks more willingly than from the testimony of the Word. Science exults in having discovered what it is pleased to call an order of development on earth tender grass, herb, tree ; moving creatures that have life in the wa- ters ; bird, reptile, beast, cattle, man. The Bible gives the same order ages before, and calls it God's successive creations. During ages on ages man's wisdom held the earth to be flat. Meanwhile, God was saying, century after cen- tury, of himself, " He sitteth upon the sphere of the earth " (Gesenins). Men racked their feeble wits for expedients to up- 234: THE WORLDS AXD THE WORD. hold the earth, and the best they could devise were ser- pents, elephants, and turtles ; beyond that no one had ever gone to see what supported them. Meanwhile, God was perpetually telling men that he had hung the earth upon nothing. Men were ever trying to number the stars. Hippar- chus counted one thousand and twenty-two; Ptolemy one thousand and twenty-six ; and it is easy to number those visible to the naked eye. But the Bible said, when there were no telescopes to make it known, that they were as the sands of the sea, " innumerable." Sci- ence has appliances of enumeration unknown to other ages, but the space-penetrating telescopes and tastime- ters reveal more worlds eighteen millions in a single system, and systems beyond count till men acknowl- edge that the stars are innumerable to man. It is God's prerogative "to number all the stars; he also calleth them all by their names." Torricelli's discovery that the air had weight was re- ceived with incredulity. For ages the air had propelled ships, thrust itself against the bodies of men, and over- turned their works. But no man ever dreamed that weight was necessary to give momentum. During all the centuries it had stood in the Bible, waiting for man's comprehension : " He gave to the air its weight " (Job xxviii. 25). The pet science of to-day is meteorology. The fluc- tuations and variations of the weather have hitherto baffled all attempts at unravelling them. It has seemed that there was no law in their tickle changes. But at length perseverance and skill have triumphed, and a single man in one place predicts the weather and winds THE WORLDS AND THE WORD. 235 for a continent. But the Bible has always insisted that the whole department was under law ; nay, it laid down that law so clearly, that if men had been willing to learn from it they might have reached this wisdom ages ago. The whole moral law is not more clearly crystallized in " Thou shalt love the Lord thy God with all thy heart, and thy neighbor as thyself," than all the fundamentals' of the science of meteorology are crystallized in these words: "The wind goeth toward the south (equator), and turneth about (up) unto the north ; it whirleth about continually, and the wind returneth again accord- ing to his circuits (established routes). All the rivers run into the sea ; yet the sea is not full : unto the place from whence the rivers come, thither they return again" (Eccles. i. 6, 7). Those scientific queries which God propounded to Job were unanswerable then; most of them are so now. " Whereon are the sockets of the earth made to sink ?" Job never knew the earth turned in sockets ; much less could he tell where they were fixed. God answered this question elsewhere. " He stretcheth the north (one socket) over the empty place, and hangeth the earth upon nothing." Speaking of the day-spring, God says the earth is turned to it, as clay to the seal. The earth's axial revolution is clearly recognized. Co- pernicus declared it early ; God earlier. No man yet understands the balancing of the clouds, nor the suspension of the frozen masses of hail, any more than Job did. Had God asked if he had perceived the length of the earth, many a man to-day could have answered yes. But the eternal ice keeps us from perceiving the breadth 236 THE WORLDS AND THE WORD. of the earth, and shows the discriminating wisdom of the question. The statement that the sun's going is from the end of the heaven, and his circuit to the ends of it, has given edge to many a sneer at its supposed assertion that the sun went round the earth. It teaches a higher truth that the sun itself obeys the law it enforces on the plan- ets, and flies in an orbit of its own, from one end of heaven in Argo to the other in Hercules. So eminent an astronomer and so true a Christian as General Mitchell, who understood the voices in which the heavens declare the glory of God, who read with delight the Word of God embodied in worlds, and who fed upon the written Word of God as his daily bread, declared, " We find an aptness and propriety in all these astronomical illustrations, which are not weakened, but amazingly strengthened, when viewed in the clear light of our present knowledge." Herschel says, "All hu- man discoveries seem to be made only for the purpose of confirming more strongly the truths that come from on high, and are contained in the sacred writings." The common authorship of the worlds and the Word becomes apparent ; their common unexplorable wealth is a necessary conclusion. Since the opening revelations of the past show an unsearchable wisdom in the Word, has that Word any prophecy concerning mysteries not yet understood, and events yet in the future ? There are certain problems as yet insolvable. We have grasped many clews, and followed them far into labyrinths of darkness, but not yet through into light. We ask in vain, "What is matter?" No man can THE WORLDS AND THE WORD. 23 7 answer. We trace it up through the worlds, till its in- creasing fineness, its growing power, and possible iden- tity of substance, seem as if the next step would reveal its spirit origin. What we but hesitatingly stammer, the Word boldly asserts. We ask, " What is force ?" No man can answer. We recognize its various grades, each subordinate to the higher cohesion dissolvable by heat; the affinity of oxygen and hydrogen in water overcome by the pierc- ing intensity of electric fire ; rivers seeking the sea by gravitation carried back by the sun ; rock turned to soil, soil to flowers ; and all the forces in nature meas- urably subservient to mind. Hence we partly under- stand what the Word has always taught us, that all lower forces must be subject to that which is highest. How easily can seas be divided, iron made to swim, water to burn, and a dead body to live again, if the highest force exert itself over forces made to be mas- tered. When we have followed force to its highest place, we always find ourselves considering the forces of mind and spirit, and say, in the words of the Scrip- tures, " God is spirit." We ask in vain what is the end of the present condi- tion of things. We have read the history of our globe with great difficulty its prophecy is still more difficult. We have asked whether the stars form a system, and if so, whether that system is permanent. We are not able to answer yet. We have said that the sun would in time become as icy cold and dead as the moon, and then the earth would wander darkling in the voids of space. But the end of the earth, as prophesied in the Word, is different : " The heavens will pass away with 238 THE WORLDS AND THE WORD. a rushing noise, and the elements will be dissolved with burning heat, and the earth and the works therein will be burned up." The latest conclusions of science point the same way. The great zones of uncondensed matter about the sun seem to constitute a resisting medium as far as they reach. Encke's comet, whose orbit comes near the sun, is delayed. This gives gravitation an overwhelming power, and hence the orbit is lessened and a revolution accomplished more quickly. Faye's comet, which wheels beyond the track of Mars, is not retarded. If the earth moves through a resisting sub- stance, its ultimate fall into the sun is certain. Wheth- er in that far future the sun shall have cooled off, or will be still as hot as to-day, Peter's description would admirably portray the result of the impact. Peter's description, however, seems rather to indicate an inter- ference of Divine power at an appropriate time before a running down of the system at present in existence, and a re-endowment of matter with new capabilities. After thousands of years, science discovered the true way to knowledge. It is the Baconian way of experi- ment, of trial, of examining the actual, instead of imag- ining the ideal. It is the acceptance of the Scriptural plan. " If a man wills to do God's will, he shall know." Oh taste and see ! In science men try hypotheses, think the best they can, plan broadly as possible, and then see if facts sustain the theory. They have adopted the Scriptural idea of accepting a plan, and then working in faith, in order to acquire knowledge. Fortunately, in the work of salvation the plan is always perfect. But, in order to make the trial under the most favora- ble circumstances, there must be faith. The faith of THE WORLDS AVD THE WORD. 239 science is amazing ; its assertions of the supersensual are astounding. It affirms a thousand things that can- not be physically demonstrated : that the flight of a rifle- ball is parabolic ; that the earth has poles ; that gases are made of particles ; that there are atoms ; that an elec- tric light gives ten times as many rays as are visible ; that there are sounds to which we are deaf, sights to which we are blind ; that a thousand objects and activi- ties are about us, for the perception of which we need a hundred senses instead of five. These faiths have near- ly all led to sight ; they have been rewarded, and the world's wealth of knowledge is the result. The Word has ever asserted the supersensuous, solicited man's faith, and ever uplifted every true faith into sight. Lowell is partly right when he sings : " Science was Faith once ; Faith were science now, Would she but lay her bow and arrows by, And arm her with the weapons of the time." Faith laid her bow and arrows by before men in pursuit of worldly knowledge discovered theirs. What becomes of the force of the sun that is being spent to-day ? It is one of the firmest rocks of science that there can be no absolute destruction of force. It is all conserved somehow. But how ? The sun con- tracts, light results, and leaps swiftly into all encircling space. It can never be returned. Heat from stars in- visible by the largest telescope enters the tastimeter, and declares that that force has journeyed from its source through incalculable years. There is no encircling dome to reflect all this force back upon its sources. Is it lost ? Science, in defence of its own dogma, should 240 THE WORLDS AND THE WORD. assign light a work as it flies in the space which we have learned cannot be empty. There ought to be a realm where light's inconceivable energy is utilized in build- ing a grander universe, where there is no night. Christ said, as he went out of the seen into the unseen, " I go to prepare a place for you ;" and when John saw it in vision the sun had disappeared, the moon was gone, but the light still continued. Science finds matter to be capable of unknown refine- ment ; water becomes steam full of amazing capabilities : we add more heat, superheat the steam, and it takes on new aptitudes and uncontrollable energy. Zinc burned in acid becomes electricity, which enters iron as a kind of soul, to fill all that body with life. All matter is capable of transformation, if not transfiguration, till it shines by the light of an indwelling spirit. Scripture readers know that bodies and even garments can be transfigured, be made anrprnrTwv (Luke xxiv. 4), shin- ing with an inner light. They also look for new heav- ens and a new earth endowed with higher powers, fit for perfect beings. When God made matter, so far as our thought per- mits us to know, he simply made force stationary and unconscious. Thereafter he moves through it with his own will. He can at any time change these forces, making air solid, water and rock gaseous, a world a cloud, or a fire-mist a stone. He may at some time re- store all force to consciousness again, and make every part of the universe thrill with responsive joy. " Then shall the mountains and the hills break forth before you into singing, and all the trees of the field clap their hands." One of these changes is to come to the earth. THE WORLDS AND THE WORD. 24-1 Amidst great noise the heaven shall flee, the earth be burned up, and all their forces be changed to new forms. Perhaps it will not then be visible to mortal eyes. Perhaps force will then be made conscious, and the flowers thereafter return our love as much as lower creatures do now. A river and tree of life may be consciously alive, as well as give life. Poets that are nearest to God are constantly hearing the sweet voices of responsive feeling in nature. "For his gayer hours She has a voice of gladness and a smile, And eloquence of beauty; and she glides Into his darker musings with a mild And gentle sympathy, that steals away Their sharpness ere he is aware." Prophets who utter God's voice of truth say, " The wilderness and the solitary place shall be glad for holy men, and the desert shall rejoice and blossom as the rose. It shall blossom abundantly and rejoice, even with joy and singing." Distinguish clearly between certainty and surmise. The certainty is that the world will pass through cata& trophic changes to a perfect world. The grave of unr formitarianism is already covered with grass. He that creates promises to complete. The invisible, impon- derable, inaudible ether is beyond our apprehension ; it transmits impressions 186,000 miles a second ; it is millions of times more capable and energetic than air. What may be the bounds of its possibility none can im- agine, for law is not abrogated nor designs disregarded as we ascend into higher realms. Law works out more beautiful designs with more absolute certainty. Why 11 242 THE WORLDS AND THE WORD. should there not be a finer universe than this, arid dis- connected from this world altogether a n't home for immortal souls? It is a necessity. God filleth all in all, is everywhere omnipotent and wise. Why should there be great vacuities, barren of power and its creative outgoings? God has fixed the stars as proofs of his agency at some points in space. But is it in points only? Science is proud of its dis- eovery that what men once thought to be empty space is more intensely active than the coarser forms of mat- ter can be. But in the long times which are past Job glanced at earth, seas, clouds, pillars of heaven, stars, day, night, all visible things, and then added : " Lo ! these are only the outlying borders of his works. What a whisper of a word we hear of Him ! The thunder of his power who can comprehend ?" Science discovers that man is adapted for mastery in this world. He is of the highest order of visible creat- ures. Neither is it possible to imagine an order of be- ings generically higher to be connected with the con- ditions of the material world. This whole secret was known to the author of the oldest writing. " And God blessed them, and God said unto them : Be fruitful, and multiply, and replenish the earth, and subdue it : and have dominion over the fish of the sea, and over the fowl of the air, and over every living thing that moveth upon the earth." The idea is never lost sight of in the sacred writings. And while every man knows he must fail in one great contest, and yield himself to death, the later portions of the divine Word offer him victory- even here. The typical man is commissioned to destroy even death, and make man a sharer in the victory. THE WORLDS AND THE WORD. 243 Science babbles at this great truth of man's position like a little child ; Scripture treats it with a breadth of perfect wisdom we are only beginning to grasp. Science tells us that each type is prophetic of a higher one. The whale has bones prophetic of a human hand. Has man reached perfection ? Is there no prophecy in him ? Not in his body, perhaps ; but how his whole soul yearns for greater beauty. As soon as he has found food, the savage begins to carve his paddle, and make himself gorgeous with feathers. How man yearns for strength, subduing animal and cosmic forces to his will ! How he fights against dark- ness and death, and strives for perfection and holiness ! These prophecies compel us to believe there is a world where powers like those of electricity and luminiferous ether are ever at hand ; where its waters are rivers of life, and its trees full of perfect healing, and from which all unholiness is forever kept. What we infer, Scrip- ture affirms. Science tells us there has been a survival of the fittest. Doubtless this is so. So in the future there will be a survival of the fittest. What is it ? Wisdom, gentle- ness, meekness, brotherly kindness, and charity. Over those who have these traits death hath no permanent power. The caterpillar has no fear as he weaves his own shroud ; for there is life within fit to survive, and ere long it spreads its gorgeous wings, and flies in the air above where once it crawled. Man has had two states of being already. One confined, dark, peculiarly nourished, slightly conscious; then he was born into another wide, differently nourished, and intensely con- scious. He knows he may be born again into a life 244 THE WORLDS AND THE WORD. wider yet, differently nourished, and even yet more in- tensely conscious. Science Las no hint how a long ascending series of developments crowned by man may advance another step, and make man laa-yytXoq equal to angels. But the simplest teaching of Scripture points out a way so clear that a child need not miss the glori- ous consummation. When Uranus hastened in one part of its orbit, and then retarded, and swung too wide, men said there must be another attracting world beyond ; and, looking there, Neptune was found. So, when individual men are so strong that nations or armies cannot break down their wills ; so brave, that lions have no terrors ; so holy, that temptation cannot lure nor sin defile them ; so grand in thought, that men cannot follow ; so pure in walk, that God walks with them let us infer an at- tracting world, high and pure and strong as heaven. The eleventh chapter of Hebrews is a roll-call of heroes of whom this world was not worthy. They were tort- ured, not accepting deliverance, that they might obtain a better resurrection. The world to come influenced, as it were, the orbits of their souls, and when their bod- ies fell off, earth having no hold on them, they sped on to their celestial home. The tendency of such souls necessitates such a world. The worlds and the Word speak but one language, teach but one set of truths. How was it possible that the writers of the earlier Scriptures described physical phenomena with wonderful sublimity, and with such penetrative truth ? They gazed upon the same heaven that those men saw who ages afterward led the world in knowledge. These latter were near-sighted, and ab- THE WORLDS AND THE WORD. 245 sorbed in the pictures on the first veil of matter ; the former were far-sighted, and penetrated a hundred strata of thickest material, and saw the immaterial pow- er behind. The one class studied the present, and made the gravest mistakes ; the other pierced the uncounted ages of the past, and uttered the profoundest wisdom. There is but one explanation. He that planned and made the worlds inspired the Word. Science and religion are not two separate depart- ments, they are not even two phases of the same truth. Science has a broader realm in the unseen than in the seen, in the source of power than in the outcomes of power, in the sublime laws of spirit than in the laws of matter; and religion sheds its beautiful light over all stages of life, till, whether we eat or whether we drink, or whatsoever we do, we may do all for the glory of God. Science and religion make common confession that the great object of life is to learn and to grow. Both will come to see the best possible means, for the attainment of this end is a personal relation to a teach er who is the Way, the Truth, and the Life. xn. THE ULTIMATE FORCE. " In the beginning was the Word, and the Word was with God, and the Word was God. The same was in the beginning with God. All things became by him, and without him was not anything made that was made * * * and bv mm all things stand together." *O thou eteraal one; whose presence bright All space doth occupy all motion guide Thou from primeval nothingness didst call First chaos, then existence. Lord, on thee Eternity had its foundation : all Sprung forth from thee of light, joy, harmony, Sole origin : all life, all beauty thine. Thy word created all, and doth create ; Thy splendor fills all space with rays divine ; Thou art and weit, and shall be glorious, great , Life-giving, life-sustaining Potentate, Thy chains the unmeasured universe surround Upheld by thee, by thee inspired with breath." DKKZHAVIN THE ULTIMATE FORCE. 249 XII. THE ULTIMATE FORCE. THE universe is God's name writ large. Thought goes up the shining suns as golden stairs, and reads the consecutive syllables all might, and wisdom, and beau- ty ; and if the heart be fine enough and pure enough, it also reads everywhere the mystic name of love. Let us learn to read the hieroglyphics, and then turn to the blazonry of the infinite page. That is the key-note ; the heavens and the earth declaring the glory of God, and men with souls attuned listening. To what voices shall we listen first ? Stand on tha shore of a lake set like an azure gem among the bosses of green hills. The patter of rain means an annual fall of four cubic feet of water on every square foot of it. It weighs sixty-two and three-tenths pounds to the cubic foot, i.e., fifty-two million tons on the surface of a little sheet of water twenty miles long by three wide. Now, all that weight of falling rain had to be lifted, a work compared to which taking up mountains and casting them into the sea is pastime. All that water had to be taken up before it could be cast down, and carried hun- dreds of miles before it could be there. You have heard Niagara's thunder ; have stood beneath the falling im- mensity; seen it ceaselessly poured from an infinite hand ; felt that you would be ground to atoms if you fell into that resistless flood. Well, all that infinity of 11* 250 THE ULTIMATE FORCE. water had to be lifted by main force, had to be taken up out of the far Pacific, brought over the Kocky Mountains ; and the Mississippi keeps bearing its wide miles of water to the Gulf, and Niagara keeps thunder- ing age after age, because there is power somewhere to carry the immeasurable floods all the time the other way in the upper air. But this is only the Alpha of power. Professor Clark, of Amherst, Massachusetts, found that such a soft and pulpy thing as a squash had so great a power of growth that it lifted three thousand pounds, and held it day and night for months. It toiled and grew un- der the growing weight, compacting its substance like oak to do the work. All over the earth this tremen- dous power and push of life goes on in the little star- eyed flowers that look up to God only on the Alpine heights, in every tuft of grass, in every acre of wheat, in every mile of prairie, and in every lofty tree that wrestles with the tempests of one hundred winters. But this is only the B in the alphabet of power. Rise above the earth, and you find the worlds tossed like playthings, and hurled seventy times as fast as a rifle-ball, never an inch out of place or a second out of time. But this is only the C in the alphabet of power. Rise to the sun. It is a quenchless reservoir of high- class energy. Our tornadoes move sixty miles an hour, those of the sun twenty thousand miles an hour. A forest on fire sends its spires of flame one hundred feet in air, the snn sends its spires of flame two hundred thousand miles. All our fires exhaust the fuel and burn out. If the sun were pure coal, it would burn out in five thousand years ; and yet this sea of unquenchable THE ULTIMATE FORCE. 251 flame seethes and burns, and rolls and vivifies a dozen worlds, and flashes life along the starry spaces for a mill- ion years without any apparent diminution. It sends out its power to every planet, in the vast circle in which it lies. It fills with light not merely a whole circle, but a dome ; not merely a dome above, but one below, and on every side. At our distance of ninety-two and a half millions of miles, the great earth feels that power in gravitation, tides, rains, winds, and all possible life every part is full of power. Fill the earth's orbit with a circle of such receptive worlds seventy thousand in- stead of one every one would be as fully supplied with power from this central source. More. Fill the whole dome, the entire extent of the surrounding sphere, bot- tom, sides, top, a sphere one hundred and eighty -five million miles in diameter, and every one of these un- countable worlds would be touched with the same pow* er as one ; each would thrill with life. This is only the D of the alphabet of power. And glancing up to the other suns, one hundred, five hundred, twelve hundred times as large, double, triple, septuple, multiple suns, we shall find power enough to go through the whole alpha- bet in geometrical ratio ; and then in the clustered suns, galaxies, and nebulae, power enough still unrepresented by single letters to require all combinations of the al- phabet of power. What is the significance of this single element of power ? The answer of science to-day is " cor- relation," the constant evolution of one force from an- other. Heat is a mode of motion, motion a result of heat. So far so good. But are we mere reasoners in a circle? Then we would be lost men, treading our round of death in a limitless forest. What is the ultimate? Reason 252 THE ULTIMATE FORCE. out in a straight line. No definition of matter allows it to originate force; only mind can do that. Hence the ultimate force is always mind. Carry your correlation as far as you please through planets, suns, nebulae, con- cretionary vortices, and revolving fire-mist there must always be mind and will beyond. Some of that will- power that works without exhaustion must take its own force and render it static, apparent. It may do this in such correlated relation that that force shall go on year after year to a thousand changing forms ; but that force must originate in mind. Go out in the falling rain, stand under the thunder- ous Niagara, feel the immeasurable rush of life, see the hanging worlds, and trace all this the carried rain, the terrific thunder with God's bow of peace upon it, and the unfailing planets hung upon nothing trace all this to the orb of day blazing in perpetual strength, but stop not there. Who made the sun ? Contrivance fills all thought. Who made the sun ? Nature says there is a rnind, and that mind is Almighty. Then you have read the first syllables, viz., being and power. What is the continuous relation of the universe to the mind from which it derived its power? Some say that it is the relation of a wound-up watch to the winder. It was dowered with sufficient power to revolve its cease- less changes, and its maker is henceforth an absentee God. Is it? Let us have courage to see. For twen- ty years one devotes ten seconds every night to put- ting a little force into a watch. It is so arranged that it distributes that force over twenty -four hours. In that twenty years more power has been put into that watch than a horse could exert at once. But suppose THE ULTIMATE FORCE. 253 one had tried to put all that force into the watch at once : it would have pulverized it to atoms. But supposing the universe had been dowered with power at first to run its enormous rounds for twenty millions of years. It is inconceivable; steel would be as friable as sand, and strengthless as smoke, in such strain. We have discovered some of the laws of the force we call gravitation. But what do we know of its essence ? How it appears to act we know a little, what it is we are profoundly ignorant. Few men ever discuss this question. All theories are sublimely ridiculous, and fail to pass the most primary tests. How matter can act where it is not, and on that with which it has no con- nection, is inconceivable. Newton said that any one who has in philosophical matters a competent faculty of thinking, could not ad- mit for a moment the possibility of a sun reaching through millions of miles, and exercising there an at- tractive power. A watch may run if wound up, but how the watch-spring in one pocket can run the watch in another is hard to see. A watch is a contrivance for distributing a force outside of itself, and if the universe runs at all on that principle, it distributes some force outside of itself. Le Sage's theory of gravitation by the infinitive hail of atoms cannot stand a minute, hence we come back as a necessity of thought to HerschePs statement. " It is but reasonable to regard gravity as a result of a con- sciousness and a will existent somewhere." Where ? I read an old book speaking of these matters, and it says of God, He hangeth the earth upon nothing; he up- holdeth constantly all things by the word of his power 254 THE ULTIMATE FORCE. By him all things consist or hold together. It teach- es an imminent mind ; an almighty, constantly exerted power. Proof of this starts up on every side. There is a recognized tendency in all high-class energy to de- teriorate to a lower class. There is steam in the boil- er, but it wastes without fuel. There is electricity in the jar, but every particle of air steals away a little, unless our conscious force is exerted to regather it. There is light in the sun, but infinite space waits to re- ceive it, and takes it swift as light can leap. We said that if the sun were pure coal, it would burn out in five thousand years, but it blazes undimmed by the million. How can it ? There have been various theories : chem- ical combustion, it has failed; meteoric impact, it is insufficient ; condensation, it is not proved ; and if it were, it is an intermediate step back to the original cause of condensation. The far-seeing eyes see in the sun the present active power of Him who first said, "Let there be light," and who at any moment can meet a Saul in the way to Damascus with a light above the brightness of the sun another noon arisen on mid-day ; and of whom it shall be said in the eternal state of un- clouded brightness, where sun and moon are no more, " The glory of the Lord shall lighten it, and the Lamb is the light thereof." But suppose matter could be dowered, that worlds could have a gravitation, one of two things must fol- low : It must have conscious knowledge of the position, exact weight, and distance of every atom, mass, and world, in order to proportion the exact amount of grav- ity, or it must fill infinity with an omnipresent attract- ive power, pnlling in myriads of places at nothing ; in THE ULTIMATE FORCE. 255 a few places at worlds. Every world must exert aii in- finitely extended power, but myriads of infinities can- not be in the same space. The solution is, one infinite power and conscious will. To see the impossibility of every other solution, join in the long and microscopic hunt for the ultimate particle, the atom ; and if found, or if not found, to a consider- ation of its remarkable powers. Bring telescopes and microscopes, use all strategy, for that atom is difficult to catch. Make the first search with the microscope: we can count 112,000 lines ruled on a glass plate in- side of an inch. But we are here looking at mountain ridges and valleys, not atoms. Gold can be beaten to the ^-j-jnnnr of an inch. It can be drawn as the coating of a wire a thousand times thinner, to the 340000000 f an inch. But the atoms are still heaped one upon an- other. Take some of the infusorial animals. Alonzo Gray says millions of them would not equal in bulk a grain of sand. Yet each of them performs the functions of respiration, circulation, digestion, and locomotion. Some of our blood-vessels are not a millionth of our size. What must be the size of the ultimate particles that freely move about to nourish an animal whose totality is too small to estimate? A grain of musk gives off atoms enough to scent every part of the air of a room. You detect it above, below, on every side. Then let the zephyrs of summer and the blasts of winter sweep through that room for forty years, bearing out into the wide world miles on miles of air, all perfumed from the atoms of that "rain of musk, and at the end of the forty years the weight of musk has not appreciably dimin- 256 THE ULTIMATE FORCE. islied. Yet uncountable myriads on myriads of atoms have gone. Our atom is not found yet. Many are the ways of searching for it which we cannot stop to consider. We will pass in review the properties with which materi- alists preposterously endow it. It is impenetrable and indivisible. Atoms of arsenic and phosphorus are one- half; and of mercury and zinc, twice the normal size. They have different shapes. They differ in weight, in quantity of combining power, in quality of combining power. They combine with different substances, in cer- tain exact assignable quantities. Thus, one atom of bro- mine combines with one of hydrogen, one of oxygen with two of hydrogen, one of nitrogen with three of hydrogen, one of silicon with four of hydrogen, etc. Hence our atom of hydrogen must have power to count, or at least to measure, or be cognizant of bulk. Again, atoms are of different sorts, as positive or negative to electric currents. They have power to take different shapes with different atoms in crystallization ; that is, there is a power in them, conscious or otherwise, that the same bricks shall make themselves into stables or palaces, sew- ers or pavements, according as the mortar varies. " No, no," you cry out; "it is only according as the builder varies his plan." There is no need to rehearse these powers much further; though not one -tenth of the supposed innate properties of this infinitesimal infinite have been recited properties which are expressed by the words atomicity, quantivalence, monad, dyad, univalent, perissad, quadrivalent, and twenty other terms, each ex- pressing some endowment of power in this invisible atom. Refer to one more presumed ability, an ability THE ULTIMATE FORCE. 257 to keep themselves in exact relation of distance and power to each other, without touching. It is well known that water does not till the space it occupies. We can put eight or ten similar bulks of different substances into a glass of water without great- ly increasing its bulk, some actually diminishing it. A philosopher has said that the atoms of oxygen and hy- drogen are probably not nearer to each other in water than one hundred and fifty men would be if scattered over the surface of England, one man to four hundred square miles. The atoms of the luminiferous ether are infinitely more diffused, and yet its interactive atoms can give 577 millions of millions of light-waves a second. And now, more preposterous than all, each atom has an at- tractive power for every other atom of the universe. The little mote, visible only in a sunbeam streaming through a dark room, and the atom, infinitely smaller, has a grasp upon the whole world, the far-off sun, and the stars that people infinite space. The Sage of Con- cord advises you to hitch your wagon to a star. But this is hitching all stars to an infinitesimal part of a wagon. Such an atom, so dowered, so infinite, so con- scious, is an impossible conception. But if matter could be so dowered as to produce such results by mechanism, could it be dowered to produce the results of intelligence ? Could it be dowered with power of choice without becoming mind ? If oxygen and hydrogen could be made able to combine into wa- ter, could the same unformed matter produce in one case a plant, in another a bird, in a third a man ; and in each of these put bone, brain, blood, and nerve in 258 THE ULTIMATE FORCE. proper relations? Matter must be mind, or subject to a present working mind, to do this. There must be a present intelligence directing the process, laying the dead bricks, marble, and wood in an intelligent order for a living temple. If we do put God behind a single veil in dead matter, in all living things he must be ap- parent and at work. If, then, such a thing as an infi- nite atom is impossible, shall we not best understand matter by saying it is a visible representation of God's personal will arid power, of his personal force, and per- haps knowledge, set aside a little from himself, still possessed somewhat of his personal attributes, still re- sponsive to his will. What we call matter may be best understood as God's force, will, knowledge, rendered apparent, static, and unweariably operative. Unless matter is eternal, which is unthinkable, there was noth- ing out of which the world could be made, but God himself ; and, reverently be it said, matter seems to re- tain fit capabilities for such source. Is not this the teaching of the Bible ? I come to the old Book. I come to that man who was taken up into the arcana of the third heaven, the holy of holies, and heard things im- possible to word. I find he makes a clear, unequivocal statement of this truth as God's revelation to him. " By faith," says the author of Hebrews, " we under- stand the worlds were framed by the word of God, so that things which are seen were not made of things which do appear." In Corinthians, Paul says But to ns there is but one God, the Father, of whom [as a source] are all things ; and one Lord Jesus Christ, by whom [as a creative worker] are all things. So in Ro- mans he says " For out of him, and through him, and to him are all things, to w r hom be glory forever. Amen.'' THE ULTIMATE FORCE. 259 God's intimate relation to matter is explained. No wonder the forces respond to his will ; no wonder pan- theism the idea that matter is God has had such a hold upon the minds of men. Matter, derived from him, bears marks of its parentage, is sustained by him, and when the Divine will shall draw it nearer to himself the new power and capabilities of a new creation shall appear. Let us pay a higher respect to the attractions and affinities ; to the plan and power of growth ; to the wisdom of the ant ; the geometry of the bee ; the mi- grating instinct that rises and stretches its wings toward a provided South for it is all God's present wisdom and power. Let us come to that true insight of the old prophets, who are fittingly called seers ; whose eyes pierced the veil of matter, and saw God clothing the grass of the field, feeding the sparrows, giving snow like wool and scattering hoar-frost like ashes, and ever standing on the bow of our wide -sailing world, and ever saying to all tumultuous forces, " Peace, be still." Let us, with more reverent step, walk the leafy soli- tudes, and say : "Father, thy hand Hath reared these venerable columns. Thou Did'st weave this verdant roof. Thou did'st look down Upon the naked earth, and forthwise rose All these fair ranks of trees. They in Thy sun Budded, and shook their green leaves in Thy breeze. "That delicate forest flower, With scented breath and looks so like a smile, Seems, as it issues from the shapeless mould, An emanation of the indwelling life, A visible token of the unfolding love That are the soul of this wide universe." BRYANT. 260 THE ULTIMATE FORCE. Philosophy has seen the vast machine of the uni- verse, wheel within wheel, in countless numbers and hopeless intricacy. But it has not had the spiritual insight of Ezekiel to see that they were every one of them full of eyes God's own emblem of the omni- scient supervision. What if there are some sounds that do not seem to be musically rhythmic. I have seen where an avalanche broke from the mountain side and buried a hapless city; have seen the face of a cliff shattered to frag- ments by the weight of its superincumbent mass, or pierced by the fingers of the frost and torn away. All these thunder down the valley and are pulverized to sand. Is this music ? No, but it is a tuning of instru- ments. The rootlets seize the sand and turn it to soil, to woody fibre, leafy verdure, blooming flowers, and de- licious fruit. This asks life to come, partake, and be made strong. The grass gives itself to all flesh, the insect grows to feed the bird, the bird to nourish the animal, the animal to develop the man. Notwithstanding the tendency of all high-class energy to deteriorate, to find equilibrium, and so be strength- less and dead, there is, somehow, in nature a tremen- dous push upward. Ask any philosopher, and lie will tell you that the tendency of all endowed forces is to find their equilibrium and be at rest that is, dead. He draws a dismal picture of the time when the sun shall be burned out, and the world float like a charnel ship through the dark, cold voids of space the sun a burned-out char, a dead cinder, and the world one dis- mal silence, cold beyond measure, and dead beyond con- sciousness. The philosopher has wailed a dirge with- THE ULTIMATE FORCE. 261 out hope, a requiem without grandeur, over the world's future. But nature herself, to all ears attuned, sings paeans, and shouts to men that the highest energy, that of life, does not deteriorate. Mere nature may deteriorate. The endowments of force must spend themselves. Wound-up watches and worlds must run down. But nature sustained by un- expendable forces must abide. Nature filled with un- expendable forces continues in form. Nature impelled by a magnificent push of life must ever rise. Study her history in the past. Sulphurous realms of deadly gases become solid worlds; surplus sunlight becomes coal, which is reserved power ; surplus carbon becomes diamonds ; sediments settle until the heavens are azure, the air pure, the water translucent. If that is the progress of the past, why should it deteriorate in the future ? There is a system of laws in the universe in which the higher have mastery over the lower. Lower pow- ers are constitutionally arranged to be overcome ; high- er powers are constitutionally arranged for mastery. At one time the water lies in even layers near the ocean's bed, in obedience to the law or power of gravi- tation. At another time it is heaved into mountain billows by the shoulders of the wind. Again it flies aloft in the rising mists of the morning, transfigured by a thousand rainbows by the higher powers of the sun. Again it develops the enormous force of steam by the power of heat. Again it divides into two light flying airs by electricity. Again it stands upright as a heap by the power of some law in the spirit realm, whose mode of working we are not yet large enough 262 THE ULTIMATE FORCE. to comprehend. The water is solid, liquid, gaseous on earth, and in air according to the grade of power oper- ating upon it. The constant invention of man finds higher and higher powers. Once he throttled his game, and often perished in the desperate struggle ; then he trapped it ; then pierced it with the javelin ; then shot it with an arrow, or set the springy gases to hurl a rifle-ball at it. Sometime he may point at it an electric spark, and it shall be his. Once he wearily trudged his twenty miles a day, then he took the horse into service and made sixty; invoked the winds, and rode on their steady wings two hundred and forty ; tamed the steam, and made almost one thousand ; and if he cannot yet send his body, he can his mind, one thousand miles a second. It all depends upon the grade of power he uses. Now, hear the grand truth of nature : as the years progress the higher grades of power increase. Either by discov- ery or creation, there are still higher class forces to be made available. Once there was no air, no usable elec- tricity. There is no lack of those higher powers now. The higher we go the more of them we find. Mr. Lockyer says that the past ten years have been years of revelation concerning the sun. A man could not read in ten years the library of books created in that time concerning the sun. But though we have solved cer- tain problems and mysteries, the mysteries have in- creased tenfold. We do not know that any new and higher forces have been added to matter since man's acquaintance with it. But it would be easy to add any number of them, or change any lower into higher. That is the THE ULTIMATE FORCE. 263 meaning of the falling granite that becomes soil, of the pulverized lava that decks the volcano's trembling sides with flowers ; that is the meaning of the grass becom- ing flesh, and of all high forces constitutionally ar- ranged for mastery over lower. Take the ore from the mountain. It is loose, friable, worthless in itself. Raise it in capacity to cast-iron, wrought -iron, steel, it becomes a highway for the commerce of nations, over the mountains and under them. It becomes bones, muscles, body for the inspiring soul of steam. It holds up the airy bridge over the deep chasm. It is obedient in your hand as blade, hammer, bar, or spring. It is inspirable by electricity, and bears hu- man hopes, fears, and loves in its own bosom. It has been raised from valueless ore. Change it again to something as far above steel as that is above ore. Change all earthly ores to highest possibility; string them to finest tissues, and the new result may fit God's hand as tools, and thrill with his wisdom and creative processes, a body fitted for God's spirit as well as the steel is fitted to your hand. From this world take opacity, gravity, darkness, bring in more mind, love, and God, and then we will have heaven. An imma- nent God makes a plastic world. When man shall have mastered the forces that now exist, the original Creator and Sustainer will say, " Be- hold, I create all things new." Nature shall be called nearer to God, be more full of his power. To the long- wandering ^Eneas, his divine mother sometimes came to cheer his heart and to direct his steps. But the god- dess only showed herself divine by her departure ; only when he stood in desolation did the hero know he had 264 THE ULTIMATE FORCE. stood face to face with divine power, beauty, and love. Not so the Christian scholars, the wanderers in Nature's bowers to-day. In the first dawn of discovery, we see her full of beauty and strength ; in closer communion, we find her full of wisdom ; to our perfect knowledge, she reveals an indwelling God in her; to our ardent love, she reveals an indwelling God in us. But the evidence of the progressive refinements of habitation is no more clear than that of progressive re- finement of the inhabitant : there must be some one to use these finer things. An empty house is not God's ideal nor man's. The child may handle a toy, but a man must mount a locomotive ; and before there can be New Jerusaleras with golden streets, there must be men more avaricious of knowledge than of gold, or they would dig them up; more zealous for love than jewels, or they would unhang the pearly gates. The uplifting refine- ment of the material world has been kept back until there should appear masterful spirits able to handle the higher forces. Doors have opened on every side to new realms of power, when men have been able to wield them. If men lose that ability they close again, and shut out the knowledge and light. Then ages, dark and feeble, follow. Some explore prophecy for the date of the grand transformation of matter by the coming of the Son of Man, for a new creation. A little study of nature would show that the date cannot be fixed. A little study of Peter would show the same thing. He says, " What manner of persons ought ye to be, in all holy conversa- tion and godliness, looking for and hastening the com- ing of the day of God, wherein the heavens being on THE ULTIMATE FORCE. 265 fire shall be dissolved, and the elements shall melt with fervent heat ? Nevertheless we, according to his prom- ise, look for a new heaven and a new earth." The idea is, that the grand transformation of matter waits the readiness of man. The kingdom waits the king. The scattered cantons of Italy were only pros- trate provinces till Victor Emanuel came, then they were developed into united Italy. The prostrate prov- inces of matter are not developed until the man is vic- tor, able to rule there a realm equal to ten cities here. Every good man hastens the coming of the day of God and nature's renovation. Not only does inference teach that there must be finer men, but fact affirms that trans- formation has already taken place. Life is meant to have power over chemical forces. It separates carbon from its compounds and builds a tree, separates the ele- ments and builds the body, holds them separate until life withdraws. More life means higher being. Cer- tainly men can be refined and recapacitated as well as ore. In Ovid's "Metamorphoses" he represents the lion in process of formation from earth, hind quarters still clay, but fore quarters, head, erect mane, and blaz- ing eye live lion and pawing to get free. We have seen winged spirits yet linked to forms of clay, but beat- ing the celestial air, endeavoring to be free; and we have seen them, dowered with new sight, filled with new love, break loose and rise to higher being. In this grand apotheosis of man which nature teaches, progress has already been made. Man has already out- grown his harmony with the environment of mere mat- ter. He has given his hand to science, and been lifted up above the earth into the voids of infinite space. He 12 266 THE ULTIMATE FORCE. has gone on and on, till thought, wearied amidst the in- finities of velocity and distance, has ceased to note them. But he is not content ; all his faculties are not filled. He feels that his future self is in danger of not being satisfied with space, and worlds, and all mental delights, even as his manhood fails to be satisfied with the ma- teriel toys of his babyhood. He asks for an Author and Maker of things, infinitely above them. He has seen wisdom unsearchable, power illimitable ; but he asks for personal sympathy and love. Paul expresses his feel- ing : every creature not the whole creation groaneth and travaileth in pain together until now, waiting for the adoption the uplifting from orphanage to parent- age a translation out of darkness into the kingdom of God's dear Son. He hears that a man in Christ is a new creation : old things pass away, all things be- come new. There is then a possibility of finding the Author of nature, and the Father of man. He begins his studies anew. Now he sees that all lines of knowl- edge converge as they go out toward the infinite mys- tery ; sees that these converging lines are the reins of government in this world ; sees the converging lines grasped by an almighty hand ; sees a loving face and form behind ; sees that these lines of knowledge and power are his personal nerves, along which flashes his will, and every force in the universe answers like a perfect muscle. Then he asks if this Personality is as full of love as of power. He is told of a tenderness too deep for tears, a love that has the Cross for its symbol, and a dying cry for its expression : seeking it, he is a new creation. He sees more wondrous things in the Word than in the THE ULTIMATE FORCE. 267 world. He comes to know God with his heart, better than he knows God's works by his mind. Every song closes with the key-note with which it be- gan, and the brief cadence at the close hints the realms of sound through which it has tried its wings. The brief cadence at the close is this: All force runs back into mind for its source, constant support, and uplifts into higher grades. Mr. Grove says, " Causation is the will, creation is the act, of God." Creation is planned and inspired for the attainment of constantly rising results. The order is chaos, light, worlds, vegetable forms, animal life, then man. There is no reason to pause here. This is not perfection, not even perpetuity. Original plans are not accomplished, nor original force exhausted. In another world, free from sickness, sorrow, pain, and death, per- fection of abode is offered. Perfection of inhabitant is necessary ; and as the creative power is everywhere present for the various uplifts and refinements of mat- ter, it is everywhere present with appropriate power for the uplifting and refinement of mind and spirit. SUMMARY OF LATEST DISCOVERIES AND CONCLUSIONS. Movements on the Sun. The discovery and measurement of the up-rush, down-rush, and whirl of currents about the sun- spots, also of the determination of the velocity of rotation by means of the spectroscope, as described (page 53), is one of the most delicate and difficult achievements of modern science. Movement of Stars in Line of Sight (page 51). The fol- lowing table shows this movement of stars, so far as at present known : APPROACHING. RECEDING. Map. Name. Rate per sec. Map. Name. Hate per sec. Fig. 71 Arcturus.. . 55 miles Fig. 69 Sirius 20 miles " 72 Vega 50 " Fr'piece Betelgtiese.. 22 " " 73 " 69 a Oygni .... Pollux 39 " 49 " Fig. 69 Rigel Castor 15 " 25 " " 67 Dubhe 46 " " 70 Regulus 15 " Sun's Appearance. This was formerly supposed to be an even, regular, dazzling brightness, except where the spots ap- peared. But the sun's surface is now known to be mottled with what are called rice grains or willow leaves. But the rice grains are as large as the continent of America. The spaces between are called pores. They constitute an innumer- able number of small spots. This appearance of the general surface is well portrayed in the cut on page 92. Close Relation between Sun and Earth. Men always knew that the earth received light from the sun. They subsequently discovered that the earth was momentarily held by the power SUMMARY OF LATEST DISCOVERIES, ETC. 269 of gravitation. But it is a recent discovery that the light is one of the principal agents in chemical changes, in molecular grouping and world -building, thus making all kinds of life possible (p. 30-36). The close connection of the sun and the earth will be still farther shown in the relation of sun-spots and auroras. One of the most significant instances is related on page 19, when the earth felt the fall of bolides upon the sun. Members of the body no more answer to the heart than the planets do to the sun. Hydrogen Flames. It has been demonstrated that the sun flames 200,000 miles high are hydrogen in a state of flaming incandescence (page 85). Sun's Distance. The former estimate, 95,513,794 miles, has been reduced by nearly one-thirtieth. Lockyer has stated it as low as 89,895,000 miles, and Proctor, in "Encyclopaedia Bri- tannica," at 91,430,000 miles, but discovered errors show that these estimates are too small. Newcomb gives 92,400,000 as within 200,000 miles of the correct distance. The data for a new determination of this distance, obtained from the transit of Venus, December 8th, 1874, have not yet been deciphered ; a fact that shows the difficulty and laboriousness of the work. Meanwhile it begins to be evident that observations of the transit of Venus do not afford the best basis for the most per feet determination of the sun's distance. Since the earth's distance is our astronomical unit of meas- ure, it follows that all other distances will be changed, when expressed in miles, by this ascertained change of the value of the standard. Oxygen in the Sun. In 1877 Professor Draper announced the discovery of oxygen lines in the spectrum of the sun. The discovery was doubted, and the methods used were criticised by Lockyer and others, but later and more delicate experiments substantiate Professor Draper's claim to the discovery. The elements known to exist in the sun are salt, iron, hydrogen, 270 SUMMARY OF LATEST DISCOVERIES, ETC. magnesium, barium, copper, zinc, cromium, and nickel. Some elements in the sun are scarcely, if at all, discoverable on the earth, and some on the earth not yet discernible in the sun. Substance of Stars. Aldebaran (Frontispiece) shows salt, magnesium, hydrogen, calcium, iron, bismuth, tellurium, anti- mony, and mercury. Some of the sun's metals do not appear. Stars differ in their very substance, and will, no doubt, introduce new elements to us unknown before. The theory that all nebulas are very distant clusters of stars is utterly disproved by the clearest proof that some of them are only incandescent gases of one or two kinds. Discoveries of New Bodies. Comets. The companion of Sirius (p. 211). The two satellites of Mars were discovered by Mr. Hall, U. S. Naval Observatory, August llth, 1877 (page 161). The outer one is called Diemos; the inner, Phobos. Sir William Herschel thought he discovered six satellites of Uranus. The existence of four of them has been disproved by the researches of men with larger telescopes. Two new ones, however, were discovered by Mr. Lassell in 1846. Saturn's Rings are proved to be in a state of fluidity and contraction (page 171). Meteors and Comets. The orbits of over one hundred swarms of meteoric bodies are fixed : their relation to, and in some cases indentity with, comets determined. Some comets are proved to be masses of great weight and solidity (page 133). Aerolites. Some have a texture like our lowest strata of rocks. There is a geology of stars and meteors as well as of the earth. M. Meunier has just received the Lalande Medal from the Paris Academy for his treatise showing that, so far as our present knowledge can determine, some of these meteors once belonged to a globe developed in true geological epochs, and which has been separated into fragments by agencies with which we are not acquainted. Dr. 0. Halm, a German lawyer, proves the existence of SUMMARY OF LATEST DISCOVERIES, ETC. 271 organic remains in the stones that come from space. From museums in Tubingen and in Vienna Halm procured himself more than six hundred chips of meteorites of the Choadrite class, proved in each case to be genuine, and having been col- lected on eighteen different occasions, partly during the pres- ent and partly during the last centurv, in Europe, Asia, and America. Minute inspection has discovered in them a quan- tity of organic remains, principally belonging to the most ancient form of porous corallines, to the genus of fossil zoo- phytes denominated Favosites, or at least bearing a very strong resemblance to these latter, though of a still smaller type. About fifty kinds of these tiny animals have been made out by Dr. Hahn, and assigned to sixteen different families. Dr. D. F. Weinland, who has devoted a year to the study of Halm's book, and testing his microscopic researches, says that it is only the shell of the Choadrite meteorite that is burnt and glazed by friction with our atmosphere. The heat does not extend so far during the short transit of the meteor as to impair the kernel, which has an appearance somewhat like coarse shell lime, of a conglomeration of petrified organic mat- ter, baked in a lump. Though only few specimens can be called well preserved, yet the substance is sufficiently distin- guishable to enable us to class most of the structures among the Polycistines and the Foramimfera. They must have ex- isted in water warm enough never to freeze down to the bottom. Where are we to seek for this water, if Professor Schiaparelli tells us that meteorites do not belong to our solar system, but are intruders from without? Very strange is the complete resemblance of all the cuttings examined to one an- other, though, as stated, they belong to stones fallen at dif- ferent periods in all parts of the globe. Are these parts of an exploded world, or have these little worlds developed life in a manner similar to larger ones? The Horizontal Pendulum. This delicate instrument is rep- 272 SUMMARY OF LATEST DISCOVERIES, ETC. resented in Fig. 82. It consists of an upright standard, strongly braced ; a weight, w, suspended by the hair-spring of a watch, B D, and held in a horizontal position by another watch-spring, A C. The weight is deflected from side to side by the slight- est influence. The least change in the level of a base thirty- nine inches long that could be detected by a spirit-level is 0".l of an arc equal to raising one end -y^W f an i" cn - But the pendulum detects a raising of one end s-ro-TrWo-o- of an inch. To ob- serve the movements of the pendu- lum, it is kept in a dark room, and a ray of light is directed to the mirror, w, and thence reflected upon a screen. Thus the least movement may be enor- mously magnified, and read and meas- ured by the moving spot on the screen. It has been discovered that when the sun rises it has sufficient attraction to incline this instrument to the east ; when it sets, to incline it to the west. The same is true of the moon. When either is exactly overhead or under- foot, of course there is no deflection. The mean deflection caused by the moon at rising or setting is 0".0l74; by the sun, 0".008. Great results are expected from this instrument hardly known as yet: among others, whether gravitation acts instantly or consumes Fig. 82. Horizontal Pendulum. time in coming from the sun. This will be shown by the time of the change of the pendulum from east to west when the sun reaches the zenith, and vice versa when it crosses the nadir. The sun will be best studied without light, in the quiet and darkness of some deep mine. SUMMAR Y OF LA TEST DISCO VERIES, ETC. 273 Light of Unseen Stars. From careful examination, it ap- pears that three-fourths of the light on a fine starlight night comes from stars that cannot be discerned by the naked eye. The whole amount of star light is about one-eightieth of that of the full moon. Lateral Movements of Stars, page 226-28. Future Discoveries A Trans-Neptunian Planet. Professor Asaph Hall says : " It is known to me that at least two Amer- ican astronomers, armed with powerful telescopes, have been searching quite recently for a trans-Neptunian planet. These searches have been caused by the fact that Professor New- comb's tables of Uranus and Neptune already begin to differ from observation. But are we to infer from these errors of the planetary tables the existence of a trans-Neptunian planet ? It is possible that such a planet may exist, but the probability is, I think, that the differences are caused by errors in the theo- ries of these planets. * * * A few years ago the remark was fre- quently made that the labors of astronomers on the solar system were finished, and that henceforth they could turn their whole attention to sidereal astronomy. But to-day we have the lunar theory in a very discouraging condition, and the theories of Mercury, Jupiter, Saturn, Uranus, and Neptune all in need of revision ; unless, indeed, Leverrier's theories of the last two plan- ets shall stand the test of observation. But, after all, such a condition of things is only the natural result of long and accu- rate series of observations, which make evident the small inequal- ities in the motions, and bring to light the errors of theory." Future discoveries will mostly reveal the laws and conditions of the higher and finer forces. Already Professor Lootnis tele- graphs twenty miles without wire, by the electric currents be- tween mountains. We begin to use electricity for light, and feel after it for a motor. Comets and Auroras show its pres- ence between worlds, and in the interstellar spaces. Let an- other Newton arise. 12* 274 ELEMENTS OF THE SOLAR SYSTEM. III! 5.s S. o 00 1C rf< ?. 2> o 0> t> C4 1 s f * S g & S S I * j= o 5 ^ JM d r4 d r4 d W (M d d d II IS g 53 d O J rH 1 B I J 4 I -1 1H I I? ^ JS J IS g K 3 en O c? C 3 5 s -SS3.t3bc2 1 1 1 1 1 1 1 1 -s i ASTRONOMICAL SYMBOLS. 275 EXPLANATION OF ASTRONOMICAL SYMBOLS. SIGNS OF THE ZODIAC. 0. Aries 1. 8 Taurus II. H Gemini III. 2p Cancer .... 30 60 90 IV. ft Leo 120 V. TIB Virgo 150 VI. =2= Libra 180' VII. TTl Scorpio 210 VIII. ^ Sagittarius 240 IX. V3 Capricornus 270 X. ? Aquarius 300 XI. ft Pisces 330 4 Conjunction. n Quadrature. 5 Opposition. Q, Ascending Node. 3 Descending Node. H. Hours. M. Minutes of Time. S. Seconds of Time. Degrees. ' Minutes of Arc. " Seconds of Arc. R. A. Right Ascension. Decl. or 1). Declination. N. P. D. Dist. from North Pole. OTHER ABBREVIATIONS USED IN THE ALMANAC. S., south, i.e., crosses the meridian; M., morning; A. afternoon; Gr. II. L. N., greatest heliocentric latitude north, i.e., greatest distancfl north of the ecliptic, as seen from the sun. 6 $ O Inf., inferior con- junction; Sup., superior conjunction. GREEK ALPHABET USBD INDICATING THE STARS. a, nlpha. /3, beta, y, gamma. , delta. t, epsilon. T,, eta. v, nu. r, tau. 9, theta. , xi. v, upsilon. t, iota. o, omicron. *, phi. c, kappa. TT, pi. x , chi. X, lambda. p, rho.