Samuel Pierpont Langley

“ Everything has an end, and so had that journey, which finally brought us to the goal of our long travel, at the foot of the highest peak of the Sierras, Mount Whitney, which rose above us in tremendous precipices, that looked hopelessly insurmountable and wonderfully near. The whole savage mountain-region, in its slow rises from the west and its descent to the desert plains in the east, is more like the chain called the Apennines, in the moon, than anything I know on the earth. ”

“ Any one, for instance, who has looked down upon the Mediterranean from the summit of Gibraltar or Capri, and can recall its curious unlikeness to its familiar aspect—its apparent stillness, the faint intricate bands of white and gray, which, thus seen, overlap it like a net-work of broad veins, and the strangely permanent patterns left by the foam, which are entirely lost to us as we approach its tossing surface—will have a not wholly inadequate idea of the first impression made by the sight of the photosphere. ”

“ We not only see here, in humid English skies, the "orange sunset waning slow," but most of us in these days of travel can perfectly testify that the clearest heavens the earth affords, the rosy tint on the snows of Mont Blanc, forerunning the dawn, or the warm glow of the sun as he sets in Egyptian skies, show this most clearly—show that the atmosphere holds back the blue rays by preference, and lets the orange through. ”

“ Remembering that the case of our supposed dweller in the cave who could not get outside, or that of the inhabitants of the ocean-floor who can not rise to the surface, is really like our own, over whose heads is a crystalline roof which no man from the beginning of time has ever got outside of, an upper sea to whose surface we have never risen—we recognize that if we could rise to the surface, leaving the medium whose effect is in dispute wholly beneath us, we should see the sun as it is, and get proof of an incontrovertible kind ”

“ The spot then moves about on the sun as a ship on the ocean, or, to employ a less inaccurate simile, like a rent in the clouds of our sky, which, while turning with the earth, both shifts its place and alters its appearance from hour to hour, the spot not being something above the sun's surface, but a gap in and below it. We seem irresistibly led to the conclusion, then, that the surface of the sun is not a solid, and, considering this freedom of motion, we are led to question if it can even be a liquid, and whether we must not look upon it as wholly vapor-like. ”

“ WHY is it that almost any one who was offered the opportunity of witnessing an eruption of Etna, or the effects of a tropical cyclone, would embrace such an occasion with eagerness, while phenomena so similar in kind, and on so far grander a scale, visible daily on the surface of the sun, excite a comparatively feeble interest in all but those devoted to their study? ”

“ What we shall see with it is far from being that sphere of dazzling light, everywhere equally brilliant, which we have been accustomed to consider the sun. The eye ranges over a vast surface, presenting at one view over five thousand times the entire area of our globe, to find everywhere diversity of shade. ”

“ In this arbitrary way our atmosphere operates, but in a far more complex manner, taking out a narrow file here and another there, in hundreds of places, all through the spectrum, but on the whole much the most in the blue, the Fraunhofer lines being merely part of the evidence of this wonderful quasi-intelligent action which bears the name of selective absorption.
Before we leave this spectrum, let us recall one most important matter. We know that here beyond the red is solar energy in the form of heat which we can not see, but not on that account any less important. ”

“ Our common failing is to believe all Nature created for our own use, and when you ask our philosophers what end is served by that host of stars, they will calmly tell you, It is there for us to look at.' In this way they could not fail to suppose that the earth was fixed in the centre of the universe, and that all the heavenly bodies were set to revolve about her, and give her light; the same propensity which leads one to desire the most honorable seat at a ceremony makes the philosopher in his system put himself at the centre of the universe if he can. ”

“ When one is in the center of one of the great barren regions of the globe, and, after looking out from the windows of the flying train on its scorched wastes for lonely leagues of habitless desolation, turns to his well-furnished dinner-table, and the fruit and ices of his dessert, he need not envy the heroes of Oriental story, who were carried across dreadful solitudes in a single night on the backs of flying genii. Ours brought us over three thousand miles to the Mohave Desert. ”

“ If that cave had been lit by sunshine coming through a reddish glass in its roof, would the perpetual dweller in it ever have had an idea but that the sun was red? How is he to know that the glass is "colored" if he has never in his life anything to compare it with? ”

“ We ourselves are, in very fact, living at the floor of a great aërial sea, whose billows roll hundreds of miles above our heads. Is it not at any rate conceivable that we may have been led into a like fallacy from judging only by what we see at the bottom? May we not, that is, have been led into the fallacy of assuming that the intervening medium above us is colorless because the light which comes through it is so? ”

“ How can he have any idea but that this is the sum of all the sun's radiations (corresponding to our idea of white or colorless light) ; will not the habit of his life confirm him in the idea that the sun is red; and will he not think that there is no color in the glass so long as he can not go outside to see? Has this any suggestion for us, who have none of us ever been outside our crystal roof to see?
We must all acknowledge, in the abstract, that habit is equally strong in us, whether we dwell in a cave or under the sky ”

“ We look up through our own air as through something so limpid in its purity that it appears scarcely matter at all, and we are apt to forget the enormous mass of what seems of such lightness, but which really presses with nearly a ton to each square foot, so that the weight of all the buildings in this great city, for instance, is less than that of the air above them. ”

“ I am not myself so far utilitarian as to wish to see this use made of our pleasant summer haunts, but there are regions of the earth at present as entirely worthless as that great African desert which it is now proposed to partly reconvert to an inland sea, a sunburned area now apparently hopelessly useless to man, and yet on which an amount of power is every year poured in utter waste which could not be made good by the consumption of all the coal known to underlie the soil of Great Britain. ”

“ There is another way, by measuring the distance, from the sun's centre, of Venus at different stages of her progress, as seen by a pair or any number of pairs of observers; but probably best of all is photography, which is to be used by nearly every station, and which will give us almost any number of pictures (as many as 150 or 200 to a station) , showing exactly how the planet looked from minute to minute to the photographer's lens—an observer which does not get flurried, is perfectly impartial, and whose observations take the form of an instantaneous but permanent record. ”

“ We may have enjoyed the metaphor without thinking that it has any physical application to ourselves, who appear to have no roof over our heads, and to see the sun's face daily; while the fact is, that if we do not see that we have a roof over our heads in our atmosphere, and do not think of it as one, it is because it seems so transparent and colorless. ”

“ There remains among the greatest problems of the future of our science the all-important one to the whole human race of the future constancy of the sun's heat, of which we have, it seems to me, no assurance of the present rate of supply. We have, it is true, every assurance that in the contraction of the solar mass and in the supply of meteoric matter, we have heat to warm the human race for periods almost beyond limit; but we learn also that this heat is tempered to us by a solar envelope, which seems to be, as far as we know, in conditions which do not favor stability. ”

“ We must, then, look at the sun with no more idea of witnessing any thing without the sphere of natural laws, than in looking at a fire across the street. It need not follow that we shall find the operation of those laws exactly the same that our limited experience has presented, and we shall still find abundant cause for admiration and wonder without introducing mysteries of our own creation. ”

“ The Challenger has dredged from the bottom of the ocean fishes which live habitually at great depths, and whose enormous eyes tell of the correspondingly faint light which must have descended to them through the seemingly transparent water. It will not be as futile a speculation as it may at first seem, to put ourselves in imagination in the condition of creatures under the sea, and ask what the sun may appear to be to them ”

“ Repeating my belief that we as yet know nothing here, or next to nothing, I yet do not mean to disparage the object of such researches, nor even to deny the possibility of their ultimate success. We can look forward, among other fair dreams for our science's future, to a time when it will enable us to predict the years of plenty or play the part of a beneficent Providence, by warning in season against those of famine, which have cost in our time so many million lives in China and in India. ”

“ He has been speaking of the chances of the sun's light failing us wholly, as it is said to have partially done in the year following the death of Cæsar, and pointing out, with what seems justice, the imperfect grounds for the confidence of mankind in the constancy of Nature's action here in the future as in the past, founded as that confidence is on an experience of the human race—so long, judged by its life, so short in comparison with Nature's own. ”

“ A determination of the distance of any remote object, which we can see but cannot reach, whether celestial or terrestrial, the sun or a mountain-top, requires that we should know either its size and the angle it fills to the eye, or else how much the direction in which we see it changes, as we change our own position by a known amount. Thus, in the latter case, a surveyor, who wishes to determine his distance from an inaccessible object of unknown size, sends an assistant to hold up a staff at the end of a line measured on the ground by a chain. ”

“ On the fourth day, after break-neck ascents and descents, we finally ascended by a ravine, down which leaped a cataract, till, at nightfall, we reached our upper camp, which was pitched by a little lake, one of the sources of the waterfall, at a height of about twelve thousand feet, but where we seemed in the bottom of a valley, nearly surrounded as we were by an amphitheatre of rocky walls which rose perpendicularly to the height of Gibraltar from the sea, and cut off all view of the desert below or even of the peak above us. ”

“ It is so seldom that the physical investigator meets any novel fact quite unawares, or finds anything except that in the field where he is seeking, that he must count it an unusual experience to come unexpectedly on even the smallest discovery. This experience I had on one of the last days of work on the spectrum on the mountain. ”

“ May I add an expression of my personal gratification in the opportunity with which you have honored me of bringing these researches before the Royal Institution, and of my thanks for the kindness with which you have associated yourselves for an hour, in retrospect at least, with that climb toward the stars which we have made together, to find, from light in its fullness, what unsuspected agencies are at work to produce for us the light of common day? ”

“ Are we not taking it for granted that the original light which we see through it is white, and that the glass is colorless, because the light seems unaltered; and is not an appeal to be made here from sense to reason, which, in the educated observer, recalls that white light is made of various colors, and that whether the original light is really white and the glass transparent, or the glass really colored and so making the white, is to be decided only by experiment, by taking away the possibly deceptive medium? ”

“ Our science, young as it is, is old enough to have had its age of fable.
Since that time, in France, in Italy, in England, and here, thousands of telescopic studies have been made with the purpose of defining these forms, and of learning more about the growth of those mysterious objects with which they are associated—the sun's spots, which drew the attention of Fabricius and Galileo, and which still attract our own more than ever to-day, with problems which seem nearly insoluble. ”

“ If the striking picture of this "Newton of the ancient world" gazing at the setting sun, to attempt, with such rude means, a portion of the task which remains unsolved after two thousand years, be recalled here, it is because it seems fittingly to remind us of the early steps of that ascent on which man's long effort has raised him to the power of questioning Nature with means of the wonderful exactness just described, and to remind us also how long human thought has rested on the great problem to which we hope this present month may bring an answer. ”

“ If we bring ourselves nearer, as it were, by an increase of magnifying power, we lose sight of the larger masses of light and shade, whose place is filled by a curious mottling of faint, inextricably confused, and intermingled moss-like patterns. ”