ception is, indeed, a tremendous flight of human thought and ingenuity! It is the courage, the audacity-one may almost call it the superhuman calmness-of astronomers, in the face of this truly overwhelming immensity-that not only redeems their study from the oppressive and terrifying character with which it at first assails the human spirit, but gives to their proceedings and discoveries, so far as the ordinary man can follow them, an unequalled fascination. The daring, the patience, the accuracy, and the supreme intellectual gifts of the great astronomers rightly fill other men with pride in the fact that there are human minds capable of revealing things of such stupendous vastness and of indicating their order and relation to one another. It is a splendid fact, and one which must give hope and courage to all men, that the astronomer's mind does not totter—it is equal to his task. Astronomers are, in fact, triumphant: they are very far indeed from suffering from the depression which Mr. Hardy's young stargazer experienced. Among the many conclusions of astronomers as to the movements of the "heavenly bodies" none is more strange and mysterious in its suggestion than that recently arrived at to the effect that in all this vast array of millions of stars, the limits of which we can neither discover nor imagine, there are two huge streams moving in opposite directions, and in one or other all the stars are involved. Whence do they start? Where are they going? There is no answer. Another conclusion, which is arrived at quite simply by the examination with the spectroscope of the light coming from the star named Vega by astronomers, is that our sun and its attendant planets are moving towards that star. It is true that it is many billions of miles away from us, but we are rushing towards it somewhat rapidly according to mundane notions— namely, at the rate of nineteen miles a second! That, I think, is a fact likely to make the sentimental young astronomer as miserable as any of the records of immensity. In fact, the only comfort to be got in view of this fact is in the enormous distances which separate us from other stars, and the length of time which must elapse before any serious consequence can ensue from this alarming career. And there is further the probability that the general result of attractions and repulsions in the vast roadway of space will, when the time comes, take us safely past Vega, just as a motor-car passes safely through the traffic and obstructing "refuges" and lampstandards of the London streets as you recline in it, abandoned to the natural forces described as chauffeurs." The spectroscope has done no less than photography to reanimate the study of astronomy. The fact is that, with these two helping means of observation, it has become possible for the ordinary man to witness and appreciate some of the discoveries of astronomers, though the true and accurate handling of all that is revealed concerning the stars is essentially a matter of measurement, and therefore only to be dealt with strictly by mathematicians. The desire to obtain ever more and more accurate measurement of the movement and the size of the heavenly bodies is the mainspring of all astronomical discovery, and, indeed, the attempt to gain more and more detailed measurement of the factors at work is the motive-more or less immediate-of all accurate investigation of nature. Recently the astronomers of the Royal Observatory at Greenwich have photographed the new comet (the third of 1907) in a way in which no comet has ever been photographed before. On many consecutive nights for several weeks they were at work photographing it on the dry plate, at intervals of two or three hours, and the pictures obtained (which I have seen at the rooms of the Royal Astronomical Society) show the most wonderful changes of form of its tail, so that they look more like the record of the changes of some living creature than those of a heavenly body. Already, in October 1909, Halley's comet, which has been anxiously awaited, has been seen, though it is not expected to be bright and visible to all until May 1910. Comets are among the exceptional delights of the astronomerthat is to say, big comets, for two or three small comets visible only by a telescope or by photography turn up every year. Some comets are expected visitors, others make their appearance quite casually, some because they apparently have no regular period, some because that period is as yet undiscovered. Edmund Halley was the first to discover the law of movement of a comet and to predict the return in 1758 of that seen in 1682. He did not live to witness the verification of his prediction. This comet, now called Halley's comet, was, he conjectured, the same which had appeared in 1531 and in 1607. His prediction of its return proved to be a year out (owing to perturbations caused by Neptune and Uranus, two planets undiscovered in his day), but it appeared in 1759, and went round once again and reappeared in 1835, and now is eagerly expected by astronomers to appear in full brilliancy in 1910. Its period is about seventy-five or seventy-six years. XXIV COMETS A COMET is so called from the hair-like stream of light or "tail," which stretches to a greater or less. length from its bright head or "nucleus." A large comet, when seen to greatest advantage, may have a tail which stretches across one-third of the "vault of heaven," and may be reckoned by astronomers at as much as one hundred and twenty million miles long. Donati's comet --which some of my readers will remember, as I do, when it visited us in 1858-was of this imposing size. Halley's comet, on the other hand, when it was last "here," namely, in 1835, showed a tail estimated by astronomers to be fifty million miles long. The tail was more than twice as long when Halley's comet appeared in 1456. There was a big comet "on view" in 1811-the year celebrated for its wine -and in recent times a fine comet appeared in 1861, and another (Coggia's comet) in 1874. The ancient records of comets are naturally full of exaggeration. Up to Milton's time-two hundred and fifty years ago-they caused the greatest terror and excitement by their sudden appearance in the sky. This is due to the fact that mankind from the very earliest periods of which we have record has not merely gazed at the "starry host" by night in solemn wonder, but even in early prehistoric times studied and watched the stars so as to know much of their movements and regular comings and goings. The earliest priests, the earliest "wise men," were those who knew the stars and could fix the seasons by their place; the earliest temples-Stonehenge, and others older still-were star-temples or observatories, and their priests were astronomers. To such a pitch did reverence for star-knowledge attain that our ancestors confused the astral signs of changing season and cycle with the cause itself of change, and attributed all kinds of mundane events and each man's fate to "the influence of the stars." Hence the sudden appearance of a flaming comet was held to be a portent, and was always supposed either to foretell or even to produce some very unpleasant event, such as a big war or a pestilence, or the death of some one supposed to be of consequence. The earliest Greek poetry enshrines the superstition, which is handed on by Virgil, and finally by Milton. In Pope's translation of the Iliad we find the helmet of the terrible Achilles described as shining "Like the red star, that from his flaming hair And Milton, in 1665, in his Paradise Lost, wrote- Incenst with indignation, Satan stood Unterrifi'd; and like a comet burn'd, In this year of the celebration of the tercentenary of Milton's birth, it is not a little curious to find that John Milton, himself a scholar of St. Paul's School, wrote those lines when Edmund Halley, the future Astronomer Royal, had just entered the same great school, then standing in St. Paul's Churchyard, as it did when I was "one of the fishes," and used to see men hanging in the Old Bailey |