power, which built the heavens, give to me wisdom to reveal, and to you power to grasp, the truths and doctrines wrested by mind from nature in its long struggle of sixty centuries of toil!

LECTURE II.

THE DISCOVERIES OF THE PRIMITIVE AGES.

O those who have given but little attention to the science of astronomy, its truths, its predictions, its revelations, are astonishing; and but for their rigorous verification would be absolutely incredible. When we look out upon the multitude of stars which adorn the nocturnal heavens, scattered in bright profusion in all directions, apparently without law, and regardless of order; when, with telescopic aid, thousands are increased to millions, and suns, and systems, and universes rise in sublime perspective, as the visual ray sweeps outward to

distances which defy the powers of arithmetic to express; how utterly futile does it seem for the mind to dare to pierce and penetrate, to number, weigh, measure, and circumscribe these innumerable millions! It is only when we remember, that from the very cradle of our race, strong and powerful minds have, in rapid and continuous succession, bent their energies upon the solution of this grand problem, that we can comprehend how it is that light now breaks in upon us from the very confines of the universe, dimly revealing the mysterious forms which lie yet half concealed in the unfathomable gulphs of space. When I reflect on the recent triumphs of human genius; when I stand on the shore of

that mighty stream of discovery, which has grown broader and deeper as successive centuries have rolled away, gathering in strength and intensity, until it has embraced the whole universe of God; I am carried backward through thousands of years, following this stream, as it contracts towards its source, till finally its silver thread is lost in the clouds and mists of antiquity. I would fain stand at the very source of discovery, and commune with that unknown god-like mind which first conceived the grand thought, that even these mysterious stars might be read, and that the bright page which was nightly unfolded to the vision of man needed no interpreter of its solemn beauties but human genius. There is, to my mind, no finer specimen of moral grandeur than that presented by him who first resolved to read and comprehend the heavens. On some lofty peak he stood, in the stillness of the midnight hour, with the listening stars as witnesses of his vows, and there, conscious of his high destiny, and of that of his race, resolved to commence the work of ages. "Here," he exclaimed, "is my watch-tower, and yonder bright orbs are henceforth my solitary companions. Night after night, year after year, will I watch and wait, ponder and reflect, until some ray shall pierce the deep gloom which now wraps the world."

Thus resolved the unknown founder of the science of the stars. His name and his country are lost for ever. What matters this, since his works, his discoveries, have endured for thousands of years, and will endure as long as the moon shall continue to fill her silver horn and the planets to roll and shine?

Go with me, then, in imagination, and let us stand beside this primitive observer, at the close of his career of nearly a thousand years, (for we must pass beyond the epoch of the deluge, and seek our first discoveries among those sages whom, for their virtues, God permitted to count their age, not by years, but by centuries,) and here we shall learn the order in which the secrets of the starry world slowly yielded themselves to long and persevering scrutiny. And now let me unfold, in plain and simple language, the train of thought, of reasoning, and research, which marked this primitive era of astronomical science. It is true that history yields no light, and tradition even fails; but such is the beautiful order in the golden chain of discovery, that the bright links which are known, reveal with certainty those which are buried in the voiceless past. If, then, it were possible to read the records of the founder of astronomy, graven on some

column of granite, dug from the earth, whither it had been borne by the fury of the deluge, we know now what its hieroglyphics would reveal with a certainty scarcely less than that which would be given by an actual discovery, such as we have amagined. We are certain that the first discovery ever recorded, as the result of human observation, was on the moon.

The sun, the moon, the stars, had long continued to rise, and climb the heavens, and slowly sink beneath the western horizon. The spectacle of day and night was then, as now, familiar to every eye; but in gazing there was no observation, and in mute wonder there was no science. When the solitary observer took his post, it was to watch the moon. Her extraordinary phases had long fixed his attention. Whence came these changes? The sun was ever round and brilliant, the stars shone with undimmed splendour, while the moon was ever waxing and waning-sometimes a silver crescent, hanging in the western sky, or full orbed, walking in majesty among the stars, and eclipsing their radiance with her overwhelming splendour. Scarcely had the second observation been made upon the moon, when the observer was struck with the wonderful fact, that she had left her place among the fixed stars, which on the preceding night he had accurately marked. Astonished, he again fixes her place by certain bright stars close to her position, and waits the coming of the following night. His suspicions are confirmed, -the moon is moving; and, what to him is far more wonderful, her motion is precisely contrary to the general revolution of the heavens-from east to west. With a curiosity deeply aroused, he watches from night to night, to learn whether she will return upon her track; but she marches steadily onward among the stars, until she sweeps the entire circuit of the heavens, and returns to the point first occupied, to recommence her ceaseless cycles.

An inquiry now arose, whether the changes in the moon, her increase and decrease, could in any way depend on her place among the fixed stars. To solve this question, required a longer period. The group of stars among which the new moon was first seen was accurately noted, so as to be recognised at the following new moon, and doubtless our primitive astronomer hoped to find that in this same group the silver crescent, when it should next appear, would be found. But in this he was disappointed; for when the moon became first faintly visible in the western sky, the group of stars which had ushered her in before,

had dippeared below the horizon, and a new group had taken its place; and thus it was discovered that each successive new moon fell farther and farther backward among the stars. By counting the days from new moon to new moon, and those which elapsed while the moon was passing round the heavens from a certain fixed star to this same star again, it was found that these two periods were different; the revolution from new to new occupying 29 days, while the sidereal revolution, from star to star, required 27 days.

This backward motion of the moon among the stars, must have perplexed the early astronomers; and, for a long while, it was utterly impossible to decide whether the motion was real or only apparent: analogy would lead to the conclusion that all motion must be in the same direction, and as the heavens revolved from east to west, it seemed impossible that the moon, which manifestly participated in this general movement, should have another and a different motion, from west to east. There was one solution of this mystery, and I have no doubt it was for a long while accepted and believed. It was this: by giving to the moon a slower motion from east to west than the general motion of the heavens, she would appear to lag behind the stars, which would, by their swifter velocity, pass by her, and thus casion in her the observed apparent motion, from west to east. We shall see presently how this error was detected.

The long and accurate vigils of the moon, and the necessity of recognising her place, by the clusters or groups of stars among which she was nightly found, had already familiarised the eye with those along her track, and even thus early the heavens began to be divided into constellations. The eye was not long in detecting the singular fact, that this stream of constellations, lying along the moon's path, was constantly flowing to the west, and one group after another apparently dropping into the sun, or, at least, becoming invisible in consequence of their proximity to this brilliant orb. A closer examination revealed the fact, that the aspect of the whole heavens was changing from month to month. Constellations which had been conspicuous in the west, and whose brighter stars were the first to appear as the twilight faded, were found to sink lower and lower towards the horizon, till they were no longer seen; while new groups were constantly appearing in the east.

These wonderful changes, so strange and inexplicable must