dissabte, 27 de juny de 2015

And just as eager to get burnt up," replied Gazen, with a smile. "Let us pass now to the planets. The little one next the sun is Mercury, who can be seen as a rosy-white star soon after sunset or before sunrise. He is about 36 million miles, more or less, from the sun; travels round his orbit in 88 days, the length of his year; and spins about his axis in 24 hours, making a day and night. His diameter is 3,000 miles, and his mass is nearly seven times that of an equal volume of water. The attraction of gravity on his surface is barely half that on the earth, and a man would feel very light there. Mercury seems to have a dense atmosphere, and probably high mountains, if not active volcanoes. The sunshine is from four to nine times stronger there than on the earth, and as summer and winter follow each other in six weeks, he is doubtless rather warm. "Venus, the 'Shepherd's Star,' and the brightest object in the heavens after the moon, can sometimes be seen by day, and casts a distinct shadow at night. She is about 67 million miles from the sun, revolves round him in 225 days, and rotates on her axis in 23 to 24 hours, or as Schiaparelli believes, in 224 days. Her diameter is 7,600 miles, and her mass nearly five times that of an equal volume of water. Gravity is rather less there than it is here. Like Mercury, she appears to have a cloudy atmosphere, and very high mountains. On the whole she resembles the earth, but is, perhaps, a younger as well as a warmer planet. "The green ball, next to Venus, is, I need hardly say, our own dear little world. Terra, or the earth, is 93 million miles from the sun, goes round him in 365 days, and turns on her axis in 24 hours less four minutes. Her diameter is 7,918 miles, and her density is 5.66 times that of water. She is attended by a single satellite, the moon, which revolves round her in 27.3 days, at a distance of 238,000 miles. The moon rotates on her axis in about the same time, and hence we can only see one side of her. She is 2,160 miles in diameter, but her mass is only one-eightieth that of the earth. A pound weight on the moon would scale six pounds on the earth. Having little or no atmosphere or water, she is apparently a dead world. "The red planet beyond the earth is Mars, who appears in the sky as a ruddy gold or coppery star. He is 141 million miles from the sun, travels his orbit in 687 days, and wheels round his axis in 24 hours 37 minutes. His diameter is 4,200 miles, and his mass about one-ninth that of the earth. A body weighing two pounds on the earth would only make half a pound on Mars. As you know, his atmosphere is clear and thin, his surface flat, and subject to floods from the melting of the polar snows. Mars is evidently a colder and more aged planet than the earth. "He is accompanied by two little moons, Phobos (Fear), which is from ten to forty miles in diameter, and revolves round him in 7 hours 39 minutes, at a distance of 6,000 miles, a fact unparalleled in astronomy; and Deimos (Rout), who completes a revolution in 30 hours 18 minutes, at a distance of 14,500 miles. "About 400 planetoids have been discovered up to now, but we are always catching more of them. Medusa, the nearest, is 198 million miles, and Thule, the farthest, is 396 million miles from the sun. Vesta, the brightest and probably the largest, a pale yellow, or, as some say, bluish white orb, visible with the naked eye, is from 200 to 400 miles in diameter. It is impossible to say which is the smallest. Probably the mass of the whole is not greater than one quarter that of the earth. "Jupiter, surnamed the 'giant planet,' who almost rivals Venus in her splendour, is 480 million miles from the sun; travels round his orbit in 12 years less 50 days; and is believed to whirl round his axis in 10 hours. His diameter is 85,000 miles, and his bulk is not only 1,200 times that of the earth, but exceeds that of all the other planets put together. Nevertheless, his mass is only 200 to 300 times that of the earth, for his density is not much greater than that of water. What we see is evidently his vaporous atmosphere, which is marked by coloured spots and bands or belts, probably caused by storms and currents, especially in the equatorial regions. Jupiter is thought to be self luminous, at least in parts, and is, perchance, a cooling star, not yet entirely crusted over. "Four or five numbered satellites, about the size of our moon and upwards, are circulating round him in orbits from 2,000 to 1,000,000 miles distant in periods ranging from 11 hours to 16 days 18 hours. "Saturn, the 'ringed planet,' who appears as a dull red star of the first magnitude, is the most interesting of all the planets. He is 884 million miles from the sun; his period of revolution is 29½ years, and he turns on his axis in 10 hours 14 minutes. His diameter is 75,000 miles, but his mass is only 94 times that of the earth, for he is lighter than pinewood. His atmosphere is marked with spots and belts, and on the whole his condition is like that of Jupiter. "Two flat rings or hoops, divided by a dark space, encircle his ball in the plane of his equator. The inner ring is over 18,000 miles from the ball, and nearly 17,000 miles broad. The gap between is 1,750 miles wide, and the outer ring is over 10,000 miles broad. The rings are banded, bright or dark, and vary in thickness from 40 to 250 miles. They consist of innumerable small satellites and meteoric stones, travelling round the ball in rather more than ten hours, and are brightest in their densest parts. Of course they form a magnificent object in the night sky of the planet, and it may be that our own zodiacal light is the last vestige of a similar ring, and not an extension of the solar corona. "Saturn has eight moons outside his rings, the nearest, Mimas, being 115,000, and the farthest, Japetus, 220,400 miles from his ball. With the exception of Japetus, they revolve round him in the plane of his rings, and when these are seen edgewise, appear to run along it like beads on a string. "Uranus, the next planet visible, is a pale star of the sixth magnitude, 1,770 million miles from the sun, and completes his round in 84 years. His axis, differing from those of the foregoing planets, lies almost in the plane of his orbit, but we cannot speak as to his axial rotation. He is 31,000 miles in diameter, and somewhat heavier, bulk for bulk, than water. Four satellites revolve round him, the nearest, Ariel, being 103,500, and the farthest, Oberon, 347,500 miles distant. Unlike the orbits of the foregoing satellites, which are nearly in the same plane as the orbits of their primaries, those of the satellites of Uranus are almost perpendicular to his own. They are travelled in periods of two and a half to thirteen and a half days. "Neptune, invisible to the naked eye, but seen as a pale blue star in the telescope, is 2,780 million miles from the sun, and makes a revolution in 165 years. His diameter is about 35,000 miles, and his density rather less than that of water. "Neptune has one satellite, at a distance of 202,000 miles, which, like those of Uranus, revolves about its primary in an orbit at a considerable angle to his own in five days twenty-one hours. Both Neptune and Uranus are probably dying suns. "Comets of unknown number travel in long elliptical or parabolic orbits round the sun at great velocities. They seem to consist partly of glowing vapours, especially hydrogen, and partly of meteoric stones. 'Shooting stars,' that is to say, stones which fall to the earth, are known to swarm in their wake, and are believed to be as plentiful in space as fishes in the sea." "The trash or leavings of creation," said I reflectively. "And the raw material, for nothing is lost," rejoined Gazen. "Now, in spite of all its diversity, there is a remarkable symmetry in the solar system. The planets are all moving round the sun in one direction along circular paths. As a rule each is nearly as far again from the sun as the next within it. Thus, if we take Mercury as ¾ inch from the sun, Venus is about 1¼ inches, the Earth 2¼, Mars 2, the planetoids 5¼, Jupiter 9¾, Saturn 14, Uranus 36, and Neptune 60 inches. On the same scale, by the way, Enckes' comet at Aphelion, its farthest distance from the sun, would be about 12 feet; Donatis almost a mile; and Alpha Centauri, a near star in the Milky Way, some ten miles. "The stately march of the planets in their orbits becomes slower the farther they are from the sun. The velocity of Mercury in its orbit is thirty, that of Jupiter is eight, and that of Neptune is only three miles a second. On the other hand, the inner planets, as a rule, take some twenty-four hours, and the outer only ten hours to spin round their axis. The inner planets are small in comparison with the outer. If we represent the sun by a gourd, 20 inches in diameter, Mercury will seem a bilberry (⅟₁₆ inch) Venus, a white currant, the Earth a black currant (¼ inch), Mars a red currant (⅛ inch), the planetoids as fine seed, Jupiter an orange or peach (2 inches), Saturn a nectarine or greengage (1 inch), Uranus a red cherry (¾ inch), and Neptune a white cherry (barely 1 inch in diameter). By putting the sun and planets in a row, and drawing a contour of the whole, we obtain the figure of a dirk, a bodkin, or an Indian club, in which the sun stands for the knob (disproportionately big), the inner planets for the handle, and the outer for the blade or body. Again, the average density of the inner planets exceeds that of the outer by nearly five to one, but the mass of any planet is greater than the combined masses of all which are smaller than it. The inner planets derive all their light and heat from the sun, and have few or no satellites; whereas the outer, to all appearance, are secondary suns, and have their own retinue of worlds. On the similitude of a clan or house we may regard the inner planets as the immediate retainers of the chief, and the outer as the chieftains of their own septs or families." "How do you account for the symmetrical arrangement?" I enquired. "The origin of the solar system is, you know, a mystery," replied the astronomer. "According to the nebular hypothesis we may imagine that two or more dark suns, perhaps encircled with planets, have come into collision. Burst into atoms by the stupendous shock they would fill the surrounding region with a vast nebula of incandescent gases in a state of violent agitation. Its luminous fringes would fly immeasurably beyond the present orbit of Neptune, and then rush inwards to the centre, only to be driven outwards again. Surging out and in, the fluid mass would expand and contract alternately, until in course of ages the fiery tides would cease to ebb and flow. If the impact had been somewhat indirect it would rotate slowly on its axis, and under the influence of gravity and centrifugal force acquire a globular shape which would gradually flatten to a lenticular disc. As it cooled and shrank in volume it would whirl the faster round its axis, and grow the denser towards its heart. By and by, as the centrifugal force overcame gravity, the nebula would part, and the lighter outskirts would be shed one after another in concentric rings to mould the planets. The inner rings, being relatively small and heavy, would probably condense much sooner than the large, light, outer rings. The planetoids are apparently the rubbish of a ring which has failed to condense into one body, perhaps through its uniformity or thinness. The separation of so big a mass as Jupiter might well attenuate the border." "If the planetoids were born of a single small ring, might not several planets be condensed from a large one?" "I see nothing to hinder it. A large ring might split into smaller rings, or condense in several centres." "Because it seems to me that might explain the distinction between the inner and the outer planets. Perhaps the outer were first thrown off in one immense ring, and then the inner in a smaller ring. Before separation the nebula viewed edgewise might resemble your Indian club." "A 'dumb-bell nebula,' like those we find in the heavens," observed Gazen. "Be that as it may, the rings would collect into balls, and some of these, especially the outer, would cast off rings which would condense into moons, always excepting the rings of Saturn, which, like the planetoids, are evidently a failure. The solar system would then appear as a group of suns, a cluster of stars, in short, a constellation. Each would be what we call a 'nebulous star,' not unlike the sun at present; that is to say, it would be surrounded by a glowing atmosphere of vapours, and perhaps meteoric matter. Under the action of gravity, centrifugal force, and tidal retardation, their orbits would become more circular, they would gradually move further apart, rotate more slowly on their axes, and assume the shapes they have now. In cooling down, new chemical compounds, and probably elements would be formed, since the so-called elements are perhaps mere combinations of a primordial substance which have been produced at various temperatures. The heavier elements, such as platinum, gold, and iron, would sink towards the core; and the lighter, such as carbon, silicon, oxygen, nitrogen, and hydrogen, would rise towards the surface. A crust would form, and portions of it breaking in or bursting out together with eruptions and floods of molten lava, would disturb the poise of the planet, and give rise to inequalities of surface, to continents, and mountains. When the crust was sufficiently stable, sound, and cool, the mists and clouds would condense into rivers, lakes, or seas, and the atmosphere would become clear. In due course life would make its appearance." "Can you account for that mystery?" "No. Science is bound in honour, no doubt, to explain all it can without calling in a special act of creation; but the origin of life and intelligence seems to go beyond it, so far. Spontaneous generation from dead matter is ruled out of court at present. We believe that life only proceeds from life. As for the hypothesis that meteoric stones, the 'moss-grown fragments of another world' may have brought life to the earth, I hardly know what to think of it." "Has life ever been found on a meteoric stone?" "Not that I know. Carbon, at all events in the state of graphite and diamond, has been got from them. They arc generally a kind of slag, containing nodules or crystals of iron, nickle, and other metals, and look to me as if they had solidified from a liquid or vapour. Are they ruins of an earlier cosmos—the crumbs of an exploded world—matter ejected from the sun—the snow of a nebulous ring—frozen spray from the fiery surge of a nebula? we cannot tell; but, according to the meteoric as distinguished from the nebular hypothesis of the solar system, the sun, planets, and comets, as well as the stars and nebula were all generated by the clash of meteorites; and not as I have supposed, of dead globes." "Which hypothesis do you believe?" "There may be some truth in both," replied Gazen. "The two processes might even go on together. What if meteorites are simply frozen nebula? It is certain that the earth is still growing a little from the fall of meteoric stones, and that part of the sun's heat comes from meteoric fuel. Most of it, however, arises from the shrinkage of his bulk. Five or ten million years ago the sun was double the size he is now. Twenty or thirty million years ago he was rather a nebula than a sun. In five or ten million more he will probably be as Jupiter is now—a smoking cinder." "And the earth—how long is it since she was crusted over?" "Anything from ten to several hundred million years. In that time the stratified rocks have been deposited under water, the land and sea have taken their present configurations; the atmosphere has been purified; plants and animals have spread all over the surface. Man has probably been from twenty to a hundred thousand years or more on the earth, but his civilization is a thing of yesterday." "How long will the earth continue fit for life?" "Perhaps five or ten million years. The entire solar system is gradually losing its internal heat, and must inevitably die of sheer inanition. The time is coming when the sun will drift through space, a black star in the midst of dead worlds. Perhaps the system will fall together, perhaps it will run against a star. In either case there would probably be a 'new heaven and a new earth.'" "Born like a phoenix from the ashes of the old," said I, feeling the justice of the well-worn simile. "I daresay the process goes on to all eternity." "Like enough." The sublime idea, with its prospect of the infinite, held us for a time in silence. At length my thoughts reverted to the original question which had been forgotten. "Now, whether should I go to Mars or Venus?" I enquired, fixing my eyes on these planets and trying to estimate their relative distances from the earth. Gazen made a mental computation, and replied with decision, "Venus." "All right," I responded. "Venus let it be."The heaven that rolls around cries aloud to you while it displays its eternal harmony, and yet your eyes are fixed upon the earth alone." DANTE. "This truth within thy mind rehearse, That in a boúndless universe Is boundless better, boundless worse. "Think you this mould of hopes and fears Could find no statelier than his peers In yonder hundred million spheres?" TENNYSON. A TRIP TO VENUS. CHAPTER I. A MESSAGE FROM MARS. While I was glancing at the Times newspaper in a morning train for London my eyes fell on the following item:— A STRANGE LIGHT ON MARS.—On Monday afternoon, Dr. Krueger, who is in charge of the central bureau at Kiel, telegraphed to his correspondents:— "Projection lumineuse dans région australe du terminateur de Mars observée par Javelle 28 courant, 16 heures.—Perrotin." In plain English, at 4 a.m., a ray of light had been observed on the disc of the planet Mars in or near the "terminator"; that is to say, the zone of twilight separating day from night. The news was doubly interesting to me, because a singular dream of "Sunrise in the Moon" had quickened my imagination as to the wonders of the universe beyond our little globe, and because of a never-to-be-forgotten experience of mine with an aged astronomer several years ago. This extraordinary man, living the life of a recluse in his own observatory, which was situated in a lonely part of the country, had, or at any rate, believed that he had, opened up a communication with the inhabitants of Mars, by means of powerful electric lights, flashing in the manner of a signal-lantern or heliograph. I had set him down as a monomaniac; but who knows? perhaps he was not so crazy after all. When evening came I turned to the books, and gathered a great deal about the fiery planet, including the fact that a stout man, a Daniel Lambert, could jump his own height there with the greatest ease. Very likely; but I was seeking information on the strange light, and as I could not find any I resolved to walk over and consult my old friend, Professor Gazen, the well-known astronomer, who had made his mark by a series of splendid researches with the spectroscope into the constitution of the sun and other celestial bodies. It was a fine clear night. The sky was cloudless and of a deep dark blue, which revealed the highest heavens and the silvery lustre of the Milky Way. The great belt of Orion shone conspicuously in the east, and Sirius blazed a living gem more to the south. I looked for Mars, and soon found him farther to the north, a large red star, amongst the white of the encircling constellations. Professor Gazen was quite alone in his observatory when I arrived, and busily engaged in writing or computing at his desk. "I hope I'm not disturbing you," said I, as we shook hands; "I know that you astronomers must work when the fine night cometh." "Don't mention it," he replied cordially; "I'm observing one of the nebulas just now, but it won't be in sight for a long time yet." "What about this mysterious light on Mars. Have you seen anything of it?" Gazen laughed. "I have not," said he, "though I did look the other night." "You believe that something of the kind has been seen?" "Oh, certainly. The Nice Observatory, of which Monsieur Perrotin is director, has one of the finest telescopes in existence, and Monsieur Javelle is well-known for his careful work." "How do you account for it?" "The light is not outside the disc," responded Gazen, "else I should ascribe it to a small comet. It may be due to an aurora in Mars as a writer in Nature has suggested, or to a range of snowy Alps, or even to a bright cloud, reflecting the sunrise. Possibly the Martians have seen the forest fires in America, and started a rival illumination." "What strikes you as the likeliest of these notions?" "Mountain peaks catching the sunshine." "Might it not be the glare of a city, or a powerful search-light—in short, a signal?" "Oh dear, no," exclaimed the astronomer, smiling incredulously. "The idea of signalling has got into people's heads through the outcry raised about it some time ago, when Mars was in 'opposition' and near the earth. I suppose you are thinking of the plan for raising and lowering the lights of London to attract the notice of the Martians?" "No; I believe I told you of the singular experience I had some five or six years ago with an old astronomer, who thought he had established an optical telegraph to Mars?" "Oh, yes, I remember now. Ah, that poor old chap was insane. Like the astronomer in Rasselas, he had brooded so long in solitude over his visionary idea that he had come to imagine it a reality." "Might there not be some truth in his notion? Perhaps he was only a little before his time." Gazen shook his head. "You see," he replied, "Mars is a much older planet than ours. In winter the Arctic snows extend to within forty degrees of the equator, and the climate must be very cold. If human beings ever existed on it they must have died out long ago, or sunk to the condition of the Eskimo." "May not the climate be softened by conditions of land and sea unknown to us? May not the science and civilisation of the Martians enable them to cope with the low temperature?" "The atmosphere of Mars is as rare as ours at a height of six miles, and a warm-blooded creature like man would expire in it." "Like man, yes," I answered; "but man was made for this world. We are too apt to measure things by our own experience. Why should we limit the potentiality of life by what we know of this planet?" "In the next place," went on Gazen, ignoring my remark, "the old astronomer's plan of signalling by strong lights was quite impracticable. No artificial light is capable of reaching to Mars. Think of the immense distance and the two atmospheres to penetrate! The man was mad, as mad as a March hare! though why a March hare is mad I'm sure I don't know." "I read the other day of an electric light in America which can be seen 150 miles through the lower atmosphere. Such a light, if properly directed, might be visible on Mars; and, for aught we know, the Martians may have discovered a still stronger beam." "And if they have, the odds against their signalling just when we are alive to the possibility of it are simply tremendous." "I see nothing incredible in the coincidence. Two heads often conceive the same idea about the same time, and why not two planets, if the hour be ripe? Surely there is one and the same inspiring Soul in all the universe. Besides, they may have been signalling for centuries, off and on, without our knowing it." "Then, again," said Gazen, with a pawky twinkle in his eye, "our electric light may have woke them up." "Perhaps they are signalling now," said I, "while we are wasting precious time. I wish you would look." "Yes, if you like; but I don't think you'll see any 'luminous projections,' human or otherwise." "I shall see the face of Mars, anyhow, and that will be a rare experience. It seems to me that a view of the heavenly bodies through a fine telescope, as well as a tour round the world, should form a part of a liberal education. How many run to and fro upon the earth, hunting for sights at great trouble and expense, but how few even think of that sublimer scenery of the sky which can be seen without stirring far from home! A peep at some distant orb has power to raise and purify our thoughts like a strain of sacred music, or a noble picture, or a passage from the grander poets. It always does one good." Professor Gazen silently turned the great refracting telescope in the direction of Mars, and peered attentively through its mighty tube for several minutes. "Is there any light?" I inquired. "None," he replied, shaking his head. "Look for yourself." I took his place at the eye-piece, and was almost startled to find the little coppery star, which I had seen half-an-hour before, apparently quite near, and transformed into a large globe. It resembled a gibbous moon, for a considerable part of its disc was illuminated by the sun. A dazzling spot marked one of its poles, and the rest of its visible surface was mottled with ruddy and greenish tints which faded into white at the rim. Fascinated by the spectacle of that living world, seen at a glance, and pursuing its appointed course through the illimitable ether, I forgot my quest, and a religious awe came over me akin to that felt under the dome of a vast cathedral. "Well, what do you make of it?" The voice recalled me to myself, and I began to scrutinise the dim and shadowy border of the terminator for the feeblest ray of light, but all in vain. "I can't see any 'luminous projection'; but what a magnificent object in the telescope!" "It is indeed," rejoined the professor, "and though we have not many opportunities of seeing it, we know it better than the other planets, and almost as well as the moon. Its features have been carefully mapped like those of the moon, and christened after celebrated astronomers." "Yourself included, I hope." "No, sir; I have not that honour. It is true that a man I know, an enthusiastic amateur in astronomy, dubbed a lot of holes and corners in the moon after his private friends and acquaintances, myself amongst them: 'Snook's Crater,' 'Smith's Bottom,' 'Tiddler's Cove,' and so on; but I regret to say the authorities declined to sanction his nomenclature." "I presume that bright spot on the Southern limb is one of the polar ice-caps," said I, still keeping my eye on the planet. "Yes," replied the professor, "and they are seen to wax and wane in winter and summer. The reddish-yellow tracts are doubtless continents of an ochrey soil; and not, as some think, of a ruddy vegetation. The greenish-grey patches are probably seas and lakes. The land and water are better mixed on Mars than on the earth—a fact which tends to equalise the climate. There is a belt of continents round the equator: 'Copernicus,' 'Galileo,' 'Dawes,' and others, having long winding lakes and inlets. These are separated by narrow seas from other islands on the north or south, such as: 'Haze Land, 'Storm Land,' and so forth, which occupy what we should call the temperate zones, beneath the poles; but I suspect they are frigid enough. If you look closely you will see some narrow streaks crossing the continents like fractures. These are the famous 'Canals' of Schiaparelli, who discovered (and I wish I had his eyes) that many of them were 'doubled,' that is, had another canal alongside. Some of these are nearly 2,000 miles long, by fifty miles broad, and 300 miles apart." "That beats the Suez Canal." "I am afraid they are not artificial. The doubling is chiefly observed at the vernal equinox, our month of May, and is perhaps due to spring floods, or vegetation in valleys of the like trend, as we find in Siberia. The massing of clouds or mists will account for the peculiar whiteness at the edge of the limb, and an occasional veiling of the landscape." While he spoke, my attention was suddenly arrested by a vivid point of light which appeared on the dark side of the terminator, and south of the equator. "Hallo!" I exclaimed, involuntarily. "There's a light!" "Really!" responded Gazen, in a tone of surprise, not unmingled with doubt. "Are you sure?" "Quite. There is a distinct light on one of the continents." "Let me see it, will you?" he rejoined, hastily; and I yielded up my place to him. "Why, so there is," he declared, after a pause. "I suspect it has been hidden under a cloud till now." We turned and looked at each other in silence. "It can't be the light Javelle saw," ejaculated Gazen at length. "That was on Hellas Land." "Should the Martians be signalling they would probably use a system of lights. I daresay they possess an electric telegraph to work it." The professor put his eye to the glass again, and I awaited the result of his observation with eager interest. "It's as steady as possible," said he. "The steadiness puzzles me," I replied. "If it would only flash I should call it a signal." "Not necessarily to us," said Gazen, with mock gravity. "You see, it might be a lighthouse flashing on the Kaiser Sea, or a night message in the autumn manoeuvres of the Martians, who are, no doubt, very warlike; or even the advertisement of a new soap." "Seriously, what do you think of it?" I asked. "I confess it's a mystery to me," he answered, pondering deeply; and then, as if struck by a sudden thought, he added: "I wonder if it's any good trying the spectroscope on it?" So saying, he attached to the telescope a magnificent spectroscope, which he employed in his researches on the nebulæ, and renewed his observation. "Well, that's the most remarkable thing in all my professional experience," he exclaimed, resigning his place at the instrument to me. "What is?" I demanded, looking into the spectroscope, where I could distinguish several faint streaks of coloured light on a darker background. "You know that we can tell the nature of a substance that is burning by splitting up the light which comes from it in the prism of a spectroscope. Well, these bright lines of different colours are the spectrum of a luminous gas." "Indeed! Have you any idea as to the origin of the blaze?" "It may be electrical—for instance, an aurora. It may be a volcanic eruption, or a lake of fire such as the crater of Kilauea. Really, I can't say. Let me see if I can identify the bright lines of the spectrum." I yielded the spectroscope to him, and scarcely had he looked into it ere he cried out— "By all that's wonderful, the spectrum has changed. Eureka! It's thallium now. I should know that splendid green line amongst a thousand." "Thallium!" I exclaimed, astonished in my turn. "Yes," responded Gazen, hurriedly. "Make a note of the observation, and also of the time. You will find a book for the purpose lying on the desk." I did as directed, and awaited further orders. The silence was so great that I could plainly hear the ticking of my watch laid on the desk before me. At the end of several minutes the professor cried— "It has changed again: make another note." "What is it now?" "Sodium. The yellow bands are unmistakable." A deep stillness reigned as before. "There she goes again," exclaimed the professor, much excited. "Now I can see a couple of blue lines. What can that be? I believe it's indium." Another long pause ensued. "Now they are gone," ejaculated Gazen once more. "A red and a yellow line have taken their place. That should be lithium. Hey, presto!—and all was dark." "What's the matter?" "It's all over." With these words he removed the spectroscope from the telescope, and gazed anxiously at the planet "The light is gone," he continued, after a minute. "Perhaps another cloud is passing over it. Well, we must wait. In the meantime let us consider the situation. It seems to me that we have every reason to be satisfied with our night's work. What do you think?" There was a glow of triumph on his countenance as he came and stood before me. "I believe it's a signal," said I, with an air of conviction. "But how?" "Why should it change so regularly? I've timed each spectrum, and found it to last about five minutes before another took its place." The professor remained thoughtful and silent. "Is it not by the light which comes from them that we have gained all our knowledge of the constitution of the heavenly bodies?" I continued. "A ray from the remotest star brings in its heart a secret message to him who can read it. Now, the Martians would naturally resort to the same medium of communication as the most obvious, simple, and practicable. By producing a powerful light they might hope to attract our attention, and by imbuing it with characteristic spectra, easily recognised and changed at intervals, they would distinguish the light from every other, and show us that it must have had an intelligent origin." "What then?" "We should know that the Martians had a civilisation at least as high as our own. To my mind, that would be a great discovery—the greatest since the world began." "But of little use to either party." "As for that, a good many of our discoveries, especially in astronomy, are not of much use. Suppose you find out the chemical composition of the nebulæ you are studying, will that lower the price of bread? No; but it will interest and enlighten us. If the Martians can tell us what Mars is made of, and we can return the compliment as regards the earth, that will be a service." "But the correspondence must then cease, as the editors say." "I'm not so sure of that." "My dear fellow! How on earth are we to understand what the Martians say, and how on Mars are they to understand what we say? We have no common code." "True; but the chemical bodies have certain well-defined properties, have they not?" "Yes. Each has a peculiarity marking it from all the rest. For example, two or more may resemble each other in colour or hardness, but not in weight." "Precisely. Now, by comparing their spectra can we not be led to distinguish a particular quality, and grasp the idea of it? In short, can the Martians not impress that idea on us by their spectro-telegraph?" "I see what you mean," said Professor Gazen; "and, now I think of it, all the spectra we have seen belong to the group called 'metals of the alkalies and alkaline earths,' which, of course, have distinctive properties." "At first, I should think the Martians would only try to attract our notice by striking spectra." "Lithium is the lightest metal known to us." "Well, we might get the idea of 'lightness' from that." "Sodium," continued the professor, "sodium is a very soft metal, with so strong an affinity for oxygen that it burns in water. Manganese, which belongs to the 'iron group,' is hard enough to scratch glass; and, like iron, is decidedly magnetic. Copper is red—" "The signals for colour we might get from the spectra direct." "Mercury or quicksilver is fluid at ordinary temperatures, and that might lead us to the idea of movement—animation—life itself." "Having got certain fundamental ideas," I went on, "by combining these we might arrive at other distinct conceptions. We might build up an ideographic or glyphic language of signs—the signs being spectra. The numerals might be telegraphed by simple occultations of the light. Then from spectra we might pass by an easy step to equivalent signals of long and short flashes in various combinations, also made by occulting the light. With such a code, our correspondence might go on at great length, and present no difficulty; but, of course, we must be able to reply." "If the Martians are as clever as you are pleased to imagine, we ought to learn a good deal from them." "I hope we may, and I'm sure the world will be all the better for a little superior enlightenment on some points." "Well, we must follow the matter up, at all events," said the professor, taking another peep through the telescope. "For the present the Martian philosophers appear to have shut up shop; and, as my nebula has now risen, I should like to do a little work on it before daybreak. Look here, if it's a fine night, can you join me to-morrow? We shall then continue our observations; but, in the meanwhile, you had better say nothing about them." On my way home I looked for the ruddy planet as I had done in the earlier part of the night, but with very different feelings in my heart. The ice of distance and isolation separating me from it seemed to have broken down since then, and instead of a cold and alien star, I saw a friendly and familiar world—a companion to our own in the eternal solitude of the universe.

HOW CAN WE GET TO THE OTHER PLANETS?


The next evening promised well, and I kept my appointment, but unfortunately a slight haze gathered in the sky and prevented us from making further observations. While hoping in vain for it to clear away, Professor Gazen and I talked over the possibility of journeying to other worlds. The gist of our argument was afterwards published in a conversation, entitled "Can we reach the other planets?" which appeared in The Day after To-morrow. It ran as follows:
I. (the writer). "Do you think we shall ever be able to leave the earth and travel through space to Mars or Venus, and the other members of the Solar System?"
G. (Checking an impulse to smile and shaking his head), "Oh, no! Never."
I. "Yet science is working miracles, or what would have been accounted miracles in ancient times."
G. "No doubt, and hence people are apt to suppose that science can do everything; but after all Nature has set bounds to her achievements."
I. "Still, we don't know what we can and what we cannot do until we try."
G. "Not always; but in this case I think we know. The celestial bodies are evidently isolated in space, and the tenants of one cannot pass to another. We are confined to our own planet."
I. "A similar objection might have been urged against the plan of Columbus."
G. "That was different. Columbus only sailed through unknown seas to a distant continent. We are free to explore every nook and cranny of the earth, but how shall we cross the immense void which parts us from another world, except on the wings of the imagination?"
I. "Great discoveries and inventions are born of dreams. There are minds which can foresee what lies before us, and the march of science brings it within our reach. All or nearly all our great scientific victories have been foretold, and they have generally been achieved by more than one person when the time came. The telescope was a dream for ages, so was the telephone, steam and electric locomotion, aerial navigation. Why should we scout the dream of visiting other worlds, which is at least as old as Lucian? Ere long, and perhaps before the century is out, we shall be flying through the air to the various countries of the globe. In succeeding centuries what is to hinder us from travelling through space to different planets?"
G. "Quite impossible. Consider the tremendous distance—the lifeless vacuum—that separates us even from the moon. Two hundred and forty thousand miles of empty space."
I. "Some ten times round the world. Well, is that tremendous vacuum absolutely impassable?"
G. "To any but Jules Verne and his hero, the illustrious Barbicane, president of the Gun Club."[1]

[1] The Voyage à la Lune, by Jules Verne.
I. "Jules Verne has an original mind, and his ideas, though extravagant, are not without value. Some of them have been realised, and it may be worth while to examine his notion of firing a shot from the earth to the moon. The projectile, if I remember, was an aluminium shell in the shape of a conical bullet, and contained three men, a dog or two, and several fowls, together with provisions and instruments. It was air tight, warmed and illuminated with coal gas, and the oxygen for breathing was got from chlorate of potash, while the carbonic acid produced by the lungs and gas-burners was absorbed with caustic potash to keep the air pure. This bullet-car was fired from a colossal cast-iron gun founded in the sand. It was aimed at a point in the sky, the zenith, in fact, where it would strike the moon four days later, that is, after it had crossed the intervening space. The charge of gun-cotton was calculated to give the projectile a velocity sufficient to carry it past the 'dead-point,' where the gravity of the earth upon it was just balanced by that of the moon, and enable it to fall towards the moon for the rest of the way. The sudden shock of the discharge on the car and its occupants was broken by means of spring buffers and water pressure."
G. "The last arrangement was altogether inadequate."
I. "It was certainly a defect in the scheme."
G. "Besides, the initial velocity of the bullet to carry it beyond the 'dead-point,' was, I think, 12,000 yards a second, or something like seven miles a second."
I. "His estimate was too high. An initial velocity of 9,000 yards, or five miles a second, would carry a projectile beyond the sensible attraction of the earth towards the moon, the planets, or anywhere; in short, to an infinite distance. Indeed, a slightly lower velocity would suffice in the case of the moon, owing to her attraction."
G. "But how are we to give the bullet that velocity? I believe the highest velocity obtained from a single discharge of cordite, one of our best explosives, was rather less than 4,000 feet, or only about three-quarters of a mile per second. With such a velocity, the projectile would simply rise to a great height and then fall back to the ground."
I. "Both of these drawbacks can be overcome. We are not limited to a single discharge. Dr. S. Tolver Preston, the well-known writer on molecular science, has pointed out that a very high velocity can be got by the use of a compound gun, or, in other words, a gun which fires another gun as a projectile.[2] Imagine a first gun of enormous dimensions loaded with a smaller gun, which in turn is loaded with the bullet. The discharge of the first gun shoots the second gun into the air, with a certain velocity. If, now, the second gun, at the instant it leaves the muzzle of the first, is fired automatically, say by utilising the first discharge to press a spring which can react on a hammer or needle, the bullet will acquire a velocity due to both discharges, and equivalent to the velocity of the second gun at the time it was fired plus the velocity produced by the explosion of its own charge. In this way, by employing a series of guns, fired from each other in succession, we can graduate the starting shock, and give the bullet a final velocity sufficient to raise it against gravity, and the resistance of the atmosphere, which grows less as it advances, and send it away to the moon or some other distant orb."

[2] Engineering, January 13th, 1893.
G. "Your spit-fire mode of progression is well enough in theory, but it strikes me as just a little complicated and risky. I, for one, shouldn't care to emulate Elijah and shoot up to Heaven in that style."
I. "If it be all right in theory, it will be all right in practice. However, instead of explosives we might employ compressed air to get the required velocity. In the air-gun or cannon, as you probably know, a quantity of air, compressed within a chamber of the breech, is allowed suddenly to expand behind the bullet and eject it from the barrel. Now, one might manage with a simple gun of this sort, provided it had a very long barrel, and a series of air chambers at intervals from the breech to the muzzle. Each of these chambers, beginning at the breech, could be opened in turn as the bullet passed along the barrel, so that every escaping jet of gas would give it an additional impulse."
G. (with growing interest). "That sounds neater. You might work the chambers by electricity."
I. "We could even have an electric gun. Conceive a bobbin wound with insulated wire in lieu of thread, and having the usual hole through the axis of the frame. If a current of electricity be sent through the wire, the bobbin will become a hollow magnet or 'solenoid,' and a plug of soft iron placed at one end will be sucked into the hole. In this experiment we have the germ of a solenoid cannon. The bobbin stands for the gun-barrel, the plug for the bullet-car, and the magnetism for the ejecting force. We can arrange the wire and current so as to draw the plug or car right through the hole or barrel, and if we have a series of solenoids end to end in one straight line, we can switch the current through each in succession, and send the projectile with gathering velocity through the interior of them all. In practice the barrel would consist of a long straight tube, wide and strong enough to contain the bullet-car without flexure, and begirt with giant solenoids at intervals. Each of the solenoids would be excited by a powerful current, one after the other, so as to urge the projectile with accelerating speed along the tube, and launch it into the vast."
G. "That looks still better than the pneumatic gun."
I. "A magnetic gun would have several advantages. For instance, the currents can be sent through the solenoids in turn as quickly as we desire by means of a commutator in a convenient spot, for instance, at the butt end of the gun, so as to follow up the bullet with ease, and give it a planetary flight. By a proper adjustment of the solenoids and currents, this could be done so gradually as to prevent a starting shock to the occupants of the car. The velocity attained by the car would, of course, depend on the number and power of the solenoids. If, for example, each solenoid communicated to the car a velocity of nine yards per second, a thousand solenoids, each magnetically stronger than another in going from breech to muzzle, would be required to give a final velocity of five miles a second. In such a case, the length of the barrel would be at least 1,000 yards. Economy and safety would determine the best proportions for the gun, but we are now considering the feasibility of the project, not its cost. With regard to position and supports, the gun might be constructed along the slope of a hill or mound steep enough to give it the angle or elevation due to the aim. As the barrel would not have to resist an explosive force, it should not be difficult to make, and the inside could be lubricated to diminish the friction of the projectile in passing through it. Moreover, it is conceivable that the car need never touch the sides, for by a proper adjustment of the magnetism of the solenoids we might suspend it in mid-air like Mahomet's coffin, and make it glide along the magnetic axis of the tube."
G. "It seems a promising idea for an actual gun, or an electric despatch and parcel post, or even a railway. The bullet, I suppose, would be of iron."
I. "Probably; but aluminium is magnetic in a lower degree than iron, and its greater lightness might prove in its favour. We might also magnetise the car, say by surrounding it with a coil of wire excited from an accumulator on board. The car, of course, would be hermetically sealed, but it would have doors and windows which could be opened at pleasure. In open space it would be warmed and lighted by the sun, and in the shadow of a planet, if need were, by coal-gas and electricity. In either case, to temper the extremes of heat or cold, the interior could be lined with a non-conductor. Liquefied oxygen or air for breathing, and condensed fare would sustain the inmates; and on the whole they might enjoy a comfortable passage through the void, taking scientific observations, and talking over their experiences."
G. "It would be a novel observatory, quite free from atmospheric troubles. They might be able to make some astronomical discoveries."
I. "A novel laboratory as well, for in space beyond the attraction of the earth there would be no gravity. The travellers would not feel a sense of weight, but as the change would be gradual they would get accustomed to it, and suffer no inconvenience."
G. "They would keep their gravity in losing it."
I. "The car, meeting with practically no resistance in the ether, would tend to move in the same direction with the same velocity, and anything put overboard would neither fall nor rise, but simply float alongside. When the car came within the sensible attraction of the moon, its velocity would gradually increase as they approached each other."
G. "Always supposing the aim of the gun to have been exact. You might hit the moon, with its large disc and comparatively short range, provided no wandering meteorite diverted the bullet from its course; but it would be impossible to hit a planet, such as Venus or Mars, a mere point of light, and thirty or forty million miles away, especially as both the earth and planet are in rapid motion. A flying rifle-shot from a lightning express at a distant swallow would have more chance of success. If you missed the mark, the projectile would wheel round the planet, and either become its satellite or return towards the earth like that of Jules Verne in his fascinating romance."
I. "Jules Verne, and other writers on this subject, appear to have assumed that all the initial effort should come from the cannon. Perhaps it did not suit his literary purpose to employ any other driving force. At all events he possessed one in the rockets of Michel Ardan, the genial Frenchman of the party, which were intended to break the fall of the projectile on the moon."
G. "If I recollect, they were actually fired to give the car a fillip when it reached the dead-point on its way back to the earth."
I. "Even in a vacuum, where an ordinary propeller could not act, the bullet may become a prime mover, and co-operate with the gun. A rocket can burn without an atmosphere, and the recoil of the rushing fumes will impel the car onwards."
G. "Do you think a rocket would have sufficient power to be of any service?"
I. "Ten or twelve large rockets, capable of exerting a united back pressure of one and a half tons during five or six minutes on a car of that weight at the earth's surface, would give it in free space a velocity of two miles a second, which, of course, would not be lost by friction."
G. "So that it would not be absolutely necessary to give the projectile an initial velocity of five miles a second."
I. "No; and, besides, we are not solely dependent on the rocket. A jet of gas, at a very high pressure, escaping from an orifice into the vacuum or ether, would give us a very high propelling force. By compressing air, oxygen, or coal-gas (useful otherwise) in iron cylinders with closed vents, which could be opened, we should have a store of energy serviceable at any time to drive the car. In this way a pressure or thrust of several tons on the square inch might be applied to the car as long as we had gas to push it forwards."
G. "Certainly, and by applying the pressure, whether from the rocket or the gas, to the front and sides, as well as to the rear of the car, you would be able to regulate the speed, and direct the car wherever you wanted to go."
I. "Moreover, beyond the range of gravitation, we could steer and travel by pumping out the respired air, or occasionally projecting a pebble from the car through a stuffing box in the wall, or else by firing a shot from a pistol."
G. "You might even have a battery of machine guns on board, and decimate the hosts of heaven."
I. "Our bullets would fly straight enough, anyhow, and I suppose they would hit something in course of time."
G. "If they struck the earth they would be solemnly registered as falling stars."
I. "Certainly they would be burnt up in passing through the atmosphere of a planet and do no harm to its inhabitants."
G. "Well, now, granting that you could propel the car, and that although your gun was badly aimed you could steer towards a planet, how long would the journey take?"
I. "The self-movement of the car would enable us to save time, which is a matter of the first importance on such a trip. In the plan of Jules Verne, the bullet derives all its motion from the initial effort, and consequently slows down as it rises against the earth's attraction, until it begins again to quicken under the gravitation of the moon. Hence his voyage to our satellite occupied four days. As we could maintain the velocity of the car, however, we should accomplish the distance in thirteen hours at a speed of five miles a second, and more or less in proportion."
G. "About as long as the journey from London to Aberdeen by rail. What about Mars or Venus?"
I. "At the same speed we should cover the 36,000,000 miles to these planets in 2,000 hours, or 84 days, that is, about three months. With a speed of ten miles a second, which is not impossible, we could reach them in six weeks."
G. "One could scarcely go round the world in the same time. But, having got to a planet, how are you going to land on it? Are you not afraid you will be dissipated like a meteorite by the intense heat of friction with the planet's atmosphere, or else be smashed to atoms by the shock?"
I. "We might steer by the stars to a point on the planet's orbit, mathematically fixed in advance, and wait there until it comes up. The atmosphere of the approaching planet would act as a kind of buffer, and the fall of the car could be further checked by our means of recoil, and also by a large parachute. We should probably be able to descend quite slowly to the surface in this way without damage; but in case of peril, we could have small parachutes in readiness as life-buoys, and leap from the car when it was nearing the ground."
G. "I presume you are taking into account the velocity of the planet in its orbit? That of the earth is 18 miles a second, or a hundred times faster than a rifle bullet; that of Venus, which is nearer the sun, is a few miles more; and that of Mars, which is further from the sun, is rather less."
I. "For that reason the more distant planets would be preferable to land on. Uranus, for instance, has an orbital velocity of four miles a second, and his gravity is about three-fourths that of the earth. Moreover, his axis lies almost exactly on the plane of the ecliptic, so that we could choose a waiting place on his orbit where the line of his axis lay in the direction of his motion, and simply descend on one of his poles, at which the stationary atmosphere would not whirl the car, and where we might also profit by an ascending current of air. The attraction of the sun is so slight at the distance of Uranus, that a stone flung out of the car would have no perceptible motion, as it would only fall towards the sun a mere fraction of an inch per second, or some 355 feet an hour; hence, as Dr. Preston has calculated, one ounce of matter ejected from the car towards the sun every five minutes, with a velocity of 880 feet a second, would suffice to keep a car of one and a half tons at rest on the orbit of the planet. Indeed, the vitiated air, escaping from the car through a small hole by its own pressure, would probably serve the purpose. Just before the planet came up, and in the nick of time we could fire some rockets, and give the car a velocity of two or three miles a second in the direction of the planet's motion, so that he would overtake us, with a speed not over great to ensure a safe descent. Our parachutes would be out, and at the first contact with the atmosphere, the car would probably be blown away; but it would soon acquire the velocity of the planet, and gradually sink downwards to the surface."
G. "What puzzles me is how you are to get back to the earth."
I. "Whoever goes must take the risk; but if, as appears likely, both Mars and Venus are inhabited by intelligent beings, we should probably be able to construct another cannon and return the way we came."
G. (smiling). "Well, I confess the project does not look so impracticable as it did. After all, travelling in a vacuum seems rather pleasant. One of these days, I suppose, we astronomers will be packed in bullets and fired into the ether to observe eclipses and comets' tails."
I. "In all that has been said we have confined ourselves to ways and means already known; but science is young, and we shall probably discover new sources of energy. It may even be possible to dispense with the gun, and travel in a locomotive car. Lord Kelvin has shown that if Lessage's hypothesis of gravitation be correct, a crystal or other body may be found which is lighter along one axis than another, and thus we may be able to draw an unlimited supply of power from gravity by simply changing the position of the crystal; for example, by raising it when lighter, and letting it fall when heavier. This form of 'perpetual motion' might be equally obtainable if Dr. Preston's theory of an ether as the cause of gravity be true. Indeed, Professor Poynting is now engaged in searching for such a crystal, which, if discovered, will upset the second law of thermo-dynamics. I merely mention this to show that science is on the track of concealed motive powers derived from the ether, and we cannot now tell what the engines of the future will be like. For ought we know, the time is coming when there will be a regular mail service between the earth and Mars or Venus, cheap trips to Mercury, and exploring expeditions to Jupiter, Saturn, or Uranus."

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