Richard A. Proctor

“ How, then, can we hope to appreciate the vastness of space whereof astronomy tells us? To the student of science attempting to conceive the immensities of whose existence he is assured, the same lesson might be taught in parable which the child of St. Augustine's vision taught the Numidian theologian. As reasonably might an infant hope to pour the waters of ocean into a hollow, scooped with his tiny fingers in the sand, as man to picture in his narrow mind the length and breadth and depth of the abysses of space in which our earth is lost. ”

“ If we accept the opinion of Newton, which, indeed, seems to me indisputable, that matter cannot act through a vacuum, then we must admit the existence of properties, as yet unthought of, in the ether of space, or in some still more subtle universe permeating that ether. If, on the other hand, we accept the belief that matter can act at a distance, then is there no miracle, either of those believed in by mankind generally, or of those more generally rejected, which exceeds in marvellousness this wonder of all the wonders of physical science. ”

“ As the astronomer sees in the sun a more glorious object than the sun of the poet, recognising in imagination not only the visible splendour of that orb, but the mighty energy with which it is swaying the motions of a scheme of circling worlds, the wondrous activities at work throughout its entire frame, the inconceivable tumult which must prevail in that seemingly silent globe, so the glories of light, rightly understood, are far more impressive than as they appeal simply to the senses. ”

“ The science of our own time tells us a still stranger story. There's not the smallest orb which thou beholdest, she says, but in his motion throbs like a mighty heart, still pulsating life to the worlds which circle round it. But while our powers of vision are limited to the narrow range of our present telescopes, we cannot watch the action of these great centres of energy, nor can we hope that the uproar of those remote fires will ever reach mortal ears, though to the mind's ear clear and distinct. ”

“ But as regards the stellar heavens we have no doubt. Of all the objects on which the eyes of remote races have rested, the celestial bodies are undoubtedly the most ancient, while at the same time they and they alone were most certainly contemplated by all mankind. From the very earliest ages, from the time when the child-man first turned his thoughts from mere animal wants to the wonders of nature, the stars, and the sun and moon and planets must have drawn to themselves the attention of all who had eyes to see even though they had no power to understand the glories of the star-depths. ”

“ For on our estimate of the sun's distance depend our ideas as to the scale, not only of the solar system, but of the whole of the visible universe. The size of the sun, his mass, and therefore his might, the scale of those wonderful operations which we know to be taking place upon, and within, and around the sun; all these relations, as well as our estimate of the size and mass of every planet, and therefore our estimate of the earth's relative importance in the solar system, depend absolutely and directly on the estimate we form of the sun's distance. ”

“ When the auroral crown is fully formed, and the vault of heaven is covered with the auroral banners, waving hither and thither silently, now fading from view, anon glowing with more intense splendour, the mind is not less impressed with a sense of the wondrous powers which surround us than when, as the forked lightnings leap from the thundercloud, the whole heavens glow with violet light, and then sink suddenly into darkness. ”

“ Very strange, then, at first must the statement seem, that we are as sure of the existence of water in all these forms on Mars as if we had sent some messenger to the planet who had brought back for study by our chemists a block of Martian ice, a vessel full of Martian water, and a flask of Martian air saturated with aqueous vapour. Indeed, I do not know of any discovery effected by man which more strikingly displays the power of human ingenuity in mastering difficulties which, at a first view, seem altogether insuperable. ”

“ It is not only amid the depths of space that these wonderfully swift motions take place in the ethereal universe. As I have said, that universe pervades ours throughout its entire extent. The densest of our solids is as freely traversed by the ether as a forest by the summer breeze. As the foliage of a thick forest may prevent the passage of fierce winds, so may a solid body prevent the passage of light-waves—though all solid bodies, as we know, do not prevent, and some scarcely even modify, the passage of light. ”

“ If, however, the changes taking place in stars, whose variations of brightness can just be recognised, must be amazing, how stupendous must be the changes affecting a star which alternates from brightness to invisibility, like Mira, the Star Wonderful, in the constellation of the Whale! how destructive those affecting a star like Eta, of the ship Argo, which has varied from the fourth magnitude to a lustre nearly equalling that of Sirius, and thence to the lowest limit of visibility, in the course of the last hundred years! ”

“ It is probable that the star acquired its full lustre in a few hours at the utmost, and quite possible that, had any one been watching the place where the star appeared, he would have been able to see the star grow into full brightness by visible change of lustre, just as the lustre of a revolving light in a distant lighthouse visibly waxes and wanes. ”

“ Thus, when we learn that a globe as large as our earth, suspended beside the moon, would seem to have a diameter exceeding hers nearly four times, so that the globe would cover a space in the heavens about thirteen times as large as the moon covers, we form a just conception of the size of the moon as compared with the earth, though the mind cannot conceive such a body as the moon or the earth really is. ”

“ I think we may fairly regard Mars as in all probability a somewhat old and decrepit planet. He is not absolutely dead, like our own moon, where we see neither seas nor clouds, neither snow nor ice, no effects, in fine, of either heat or cold. But I think he has passed far on the road towards planetary death,—that is, towards that stage of a planet's existence when at least the higher forms of life can no longer exist upon the planet's surface. ”

“ Among the waves which reach the eye many, nay, most, are so small that ordinary vision cannot perceive their action. Take, however, a telescope, and so gather them together as to intensify this action, and they are rendered perceptible, just as the unnoticed heaving of ocean becomes a manifest wave-motion when it reaches a regularly narrowing inlet. Thus, from stars so remote that their light has required thousands, or, even in some cases, perhaps, hundreds of thousands of years in reaching us, the light-waves flow steadily in upon us. ”

“ What is that mysterious movement of some essence pervading all space, whereby, from remotest depths, news is brought to us, after journeys lasting many years, though space is traversed at a rate exceeding more than ten million times the velocity of the swiftest express train?
Light is in reality the result of undulations in what is called the ether of space, a perfectly transparent, almost perfectly elastic medium, occupying not only void space, but flowing as freely through the densest solids as the summer breeze flows through the forest trees. ”

“ Even more startling are the thoughts suggested by a view of the starlit heavens. From hundreds of suns at once the light-waves which have traversed varying but all enormous distances pour in upon the small circle of the eye-pupil, waves of many kinds coming in together from each sun. ”

“ We know that in the case of the sun, where a much mightier contractive power is at work, a much more intense heat so resists it that the sun has a mean density no greater than Jupiter's. We have every reason, then, which bulk and mass can supply, to believe that Jupiter is far hotter than the earth—that in fact, as the sun, exceeding Jupiter more than 1000 times in volume, is many times hotter than he is, so Jupiter, exceeding our earth 1200 times in volume, is very much hotter than the earth. ”

“ It is wonderful to reflect, when we look at the dull, slow-moving Saturn, that not only is the planet itself 700 times larger than the earth, not only is it girdled about by a ring system having a span exceeding more than 20 times the diameter of this earth on which we live, but that the entire span of the system over which that distant planet rules exceeds more than eighteen-fold the distance separating our earth from the moon. ”

“ We might then picture to ourselves every orb in the solar system carrying onward its faintly luminous crowns of boreal and austral light, not shining with constant lustre, or in the same constant position, but at one time leaping in coloured steamers to a great distance from the body they adorned, and anon sinking down and growing fainter and fainter, or occasionally disappearing altogether. ”

“ Seeing that, on the other hand, there are abundant reasons for believing that planets differ very widely as regards the duration of the various stages of their life, and that our earth is by no means one of the longest lived, we may very fairly expect to find among the planets some which are very much younger than our earth,—not younger, it will be understood, in years, but younger in the sense of being less advanced in development. When we further find that all the evidence accords with this view, we may regard it as the one to which true science points. ”

“ We cannot live without light and heat, for instance, and again, light and heat affect matter as we know it; but they thus exist and affect such matter by means only of a form of matter unlike any which we can conceive. It is certain that if absolute vacancy separated our earth from the sun, even by the narrowest imaginable gap, his heat and light could never reach us. They could no more pass that vacant space than the wave-motion of water can cross a space where water itself is wanting. ”

“ It is hardly going too far to say that our powers of actual conception are limited to the extent of space over which the eye seems to range in the daytime. Of course in the daytime, at least in clear weather, there is one direction in which the eyesight ranges over a distance of many millions of miles,—namely, where we see the sun. But the sense of sight is not cognisant of that enormous distance, and simply presents the sun to [18] us as a bright disc in the sky, or perhaps rather nearer to us than the sky. Even the distance of the sky itself is under-estimated. ”

“ In this superiority of bulk, nearly four times greater than his vast superiority of mass, we find the first direct evidence from observation in favour of the theory that Jupiter is still intensely hot. How can a mass so vast, possessing an attractive power in its own substance so great that, under similar conditions, it should be compressed to a far greater degree than our earth, and be, therefore, considerably more dense, come to be considerably rarer? ”

“ It is difficult when we look at the star-lit heavens, suggestive as they are of solemn peace, to conceive the stupendous energy, the fierce uproar and tumult, of which even the faintest visible star in reality tells us. ”

“ Light travels, as we know, with a velocity so enormous, that, by comparison with it, all the velocities we are familiar with seem absolutely as rest. But gravity acts so quickly that even the velocity of light becomes as rest by comparison with the velocity of the propagation of gravity. Laplace had occasion, now nearly a century ago, to inquire whether a certain change in the moon's motion, by which she seemed to be gradually hastening her motion round the earth, might not be caused by the circumstance that gravity requires time for its action to be propagated over great distances. ”

“ But there is a striking contrast between the feelings with which we regard the safe splendours of the aurora and the terrible glory of the lightning flash. One display we contemplate with the calmness engendered by absolute security; the other—no matter how little the fear of death may affect the reason—cannot be regarded without exciting the consciousness of danger. ”

“ But there is a way of viewing the immensities of space which, though not aiding us indeed to conceive them, enables the mind to picture their proportions better than any other. The dimensions of the earth's path around the sun sink into insignificance beside those of the outermost planets; but these in their turn dwindle into nothingness beside those of some among the comets. ”

“ It seems as though men could not divest themselves of the idea that our earth's history is the history of the solar system and of the universe. Precisely as children can hardly be [194] brought to understand, for a long time, what history really means, how generation after generation of their own race has passed away, and how their own race has succeeded countless others, so science, still young, seems scarcely to appreciate the real meaning of its own discoveries. ”