SUN-RAYS AND STAR-BEAMS.

BY AGNES GIBERNE, AUTHOR OF 'SUN, MOON, AND STARS,' 'THE WORLD'S FOUNDATIONS,' 'THE OCEAN OF AIR,' ETC.

I.-ASTRONOMY OLD AND NEW.

It is no easy matter to guess when first the science of Astronomy sprang into being. There are other ancient branches of learning, but surely few, if any, more ancient than the study of the stars. Geology beside Astronomy is as a babe in the cradle beside an old and gray-headed man; and of three-fourths at least of the 'Ologies the same may be said.

Astronomy was in existence before the British nation was heard of; before Saxons or Franks had sprung into being; before the Roman Empire held its iron rule; before the Grecian Empire flourished; before the earlier Persian Empire, and the yet earlier Assyrian Empire, had sway.

Among the ancient Chaldeans were devoted star-gazers; much more devoted than the common run of educated Saxons in this Nineteenth Century. They earnestly sought, in the dim intellectual light of those ages, to read the meaning of heaven's countless lamps. What do we in modern days more than this? We have better instruments and more practised modes of reasoning, and we have the collected pile of knowledge built up by our forefathers through decades of centuries. But our search is the same as was theirs-to know the very truth about the stars! Not merely to start some pretty theory, and then to prove that our theory must be right, because we have been so clever as to start it; but to discover what IS in those regions of space. No lower aim than this is worthy to be called scientific.

Of course, mistakes are made. How should it be otherwise? A man, finding his way for the first time, at night, through a wild and unknown country, will almost certainly take some wrong turns before he discovers the right road.

In Astronomy, as in other natural sciences, blunders are a necessity, if advance is to be made. We have to grope our way to knowledge through observation and conjecture-in simpler terms, through gazing and guessing. Observation leads to conjecture, and conjecture is proved or disproved by later observation. If proved, it takes its place in time among accepted truths; if disproved, it is flung aside.

'This is the way we go in science, as in everything else,' wrote Airey. 'We have to make out that something is true; then we find out, under certain circumstances, that it is not quite true; and then we have to consider and find out how the departure can be explained.' Such 'making out' and 'finding out' must, and does, sometimes mean the giving up of an old theory or conjecture, and the putting of a new one in its place.

The greatest men have occasionally made the greatest mistakes, and quite naturally, because they deal with and handle the greatest subjects. Little ordinary men make blunders perpetually, but they do it in connection with such unimportant matters that no one pays any particular heed. When a great man makes a mistake, all the world hears of it.

There are men whose intellects beside the intellects of common men are as the Matterhorn beside a molehill; yet the Matterhorn is not Heaven. It is only an earthly mountain, great in comparison with molehills, small in comparison with the heights and depths of the Universe.

It is no disparagement to such a man to allow that he makes mistakes. If he be morally great, as well as intellectually great, he will, when he discovers his error, frankly admit the same, giving readily up his dearest theory in the pursuit of truth. Schoolgirls in their teens and schoolboys in knickerbockers are always in the right; and men and women of particularly limited intellect never by any chance make a mistake; but brains of large capacity are very apt to avow themselves wiser to-day than they were yesterday.

Astronomy, as an infant science, existed in the days when the Pyramids were juvenile, and when the Assyrian bulls were modern. How much farther back still, who shall say? We cannot name the earliest people whose shepherd-sages gazed with intelligent eyes upon the midnight sky, and noted the nightly sweep of all the stars across the firmament.

That was naturally a first step. The journey of the sun by day, the journeys of moon and stars by night, could not but

claim attention. Very early, too, the stars were grouped into constellations, and to these constellations were given names, many of which have been handed down to the present day, practically unchanged. Orion, with his glittering sword and belt, bore in the days of Job the same shape as now; and Abraham looked, as we do, upon the uncertain shimmer of the Pleiades. The Great Bear's body and tail were outlined then as at present; and the pointers belonging to the body of the Great Bear pointed to the Pole-star, in the tip of the Little Bear's tail, as they have pointed ever since.

So men early named the stars 'fixed stars,' because they continued unchangeably fixed in their relative positions—that is, in the position held by each star with respect to his neighbours— although the whole mass of them nightly journeyed in company, many constellations rising and setting by night, like the sun by day.

Then, very early also, the planets were noticed-not fixed, like the stars in changeless groups, but ever moving to and fro, or onward and backward. So they were called Planets, or Wanderers, and individual names were given to them, and careful note was kept of their pathways among the stars. Also the shifting of star-groups with the seasons was seen the appearance of some constellations in summer, not seen in winter, and vice versa. All these facts received attention, and were long and deeply considered.

But a wide difference existed between the Astronomy of those days and of these. The whole ancient science was founded upon a great error. Men held, as a fact of unquestionable certainty, that this globe of ours, this little spinning whirling ball, only some eight thousand miles in diameter, was a vast plain, immovably fixed upon a solid foundation, extending to almost infinite distances. They held that around this motionless centre circled the other heavenly bodies; a little sun, a little moon, and a few thousand twinkling specks of light, all placed near at hand, for the sole purpose of lighting and warming our earth.

Conjecture after conjecture was started to explain the various perplexing motions of sun and moon and planets. At first, the very idea of the sun descending below the horizon could not be entertained, and he was supposed to be boated mysteriously

*For such particulars, more fully explained, see 'Sun, Moon, and Stars, New and Revised Edition, by the author of these papers (Seeley & Co.).

round the North Pole, every night, by Vulcan, the operation being hidden from sight by intervening mountains.

The next step was a difficult one, even to realise that our earth did not rest upon any kind of solid foundation, but that sun, moon, planets, stars, each and all, actually did pass downunderneath, so to speak-right round the solid body of the earth; and did actually come up again on the other side.

Of course, 'down' and 'up' used in this sense are entirely erroneous terms, since the sky and all heavenly bodies are invariably overhead to each part of the earth. But our ancestors would naturally take that view of the question.

Anything more bewildering to the mind of ancient man than this notion of a substantial world floating in empty space, supported upon nothing, upheld by nothing, can hardly be imagined. As yet, nothing, or almost nothing, was known of the controlling Laws of Nature. The very suspicion of gravitation, as an universal law, lay in the far future, waiting for the intellect of a Newton to call it out of apparent chaos; and the balance of opposing forces, by means of which the Solar System may almost be said to exist, could not be so much as guessed at. Men still clung to the thought of earth as the great Universe centre, and still believed in a little sun busily circling round her.

Simple as were these early astronomers, and crude as were many of their theories, they yet managed to map out correctly the sun's path in the heavens-his apparent path, which they maintained to be his real path. They watched eclipses, and arrived at a very fair notion of their causes. They knew the five chief planets-Mercury, Venus, Mars, Jupiter and Saturn, and could correctly describe these planets' various paths. By all this steadfast watching they paved a way to later discoveries and fuller knowledge.

One word more as to scientific theory. You sometimes hear people say, "Oh, that is mere theory: I have no patience with theories.' It is quite right never hastily to accept a new theory as a proved truth; but neither should we always fling it impatiently away. A certain amount of theorizing, in science, is an absolute necessity, if men would arrive at truth.

Suppose, once more, that you are walking in a dark wood, trying to find your way. You see some dark object looming ahead, and you say, 'I think it is a man.' Coming nearer, this theory has to be given up, for you find the object to be a bush. Or you say: 'I think this little side-path will lead me right,' and

you try it; and after a while you find that it brings you back to where you stood before. So the theory of that path being yours has also to be given up. Yet you could hardly walk through such a forest and not form a few theories, some wrong, some right— unless you sat down with folded hands and made no advance at all.

Our ancestors might have done this. They might have said, 'Oh, we don't know anything about the stars. No use to trouble ourselves.' Then they would have been at a standstill in their ignorance, and modern Astronomy, which is built upon the ruins of past theories, would have suffered long delay.

Suppose that, instead of being in a wood, you were on the wide sea at night, in a little boat; and suppose that round about you, at different distances, were many other little boats, each carrying its tiny light. Suppose that you and they were all moving silently in circles, each round a centre-some in larger and some in smaller circles, some faster and some more slowly. Can you not fancy how bewildering the effect would be?-how some unreal movements, due to your own motion, would seem to be real, and how some real motions would seem to be unreal?

If, in addition, you suppose that your own motion is quite unknown to yourself; that your boat travels so gently and softly as all the while to seem to be at rest; then the matter becomes much more complicated. Then all changes of position among the other boats are laid to the charge of their own movements, while really many of them are due to your movements. This was actually the mistake made by our ancestors, with regard to the earth and the other heavenly bodies.

Much perplexity existed, for early observers, in the motions of the planets, viewed, as was then supposed, from a motionless earth. Mars, for instance, would be observed first to make steady and quick advance, day by day: then to slacken his pace: then to come to a complete pause: then actually to go backward: then again to come to a standstill, again once more to advance. We know now that this complexity of movements is caused partly by our own motion, just as the forward motion of a boat at sea might make another boat, travelling the same way but more slowly, to seem to go back; and also by the fact that Mars, when on his orbit on the other side of the sun, does actually travel in an opposite direction from ourselves.

So long, however, as our earth was counted always the