« AnteriorContinuar »
we can reach back with certainty and fix the epoch of the record.
No such monument has ever been found; but there are occasional notices of astronomical phenomena, found among the Greek and Roman poets, which at least give color to conjecture. Virgil informs us that “the White Bull opens with his golden horns the year."
“Candidus auratis aperit cum cornibus annum,
Taurus." This statement we know is not true, if applied to the
age in which the poet wrote, and seems to be the quotation of an ancient tradition. If this conjecture be true, this tradition must have been carried down the stream of time for more than two thousand years, to reach the age in which the poet wrote. Although these conjectures are vague and uncertain, the frequent allusions to the constellations of the zodiac, in the old Hebrew Scriptures, and in the works of all ancient writers, sufficiently attest the extreme an tiquity of these arbitrary groupings of the stars.
In taking leave of the primitive ages of astronomy, and in entering on that portion of the career of research and discovery whose history has been preserved, let us pause for a moment and consider the position occupied by the human mind at this remark able epoch.
Thus far the eye had done its work faithfully. Through long and patient watching, it had revealed the facts, from which reason had wrought out her great results. The stars grouped into constellations, glittered in the blue concave of a mighty sphere, whose centre was occupied by the earth. Within this hollow sphere, sun, moon and planets, kept their appointed courses, and performed their ceaseless jour nies. Their wanderings had been traced,—their pathway in the heavens was known,-their periods determined,—the inclinations of their orbits fixed. So accurately had the eye followed the sun and moon, that it had learned to anticipate their relative positions, their oppositions and conjunctions, till reaching forward, it had robbed the dread eclipse of its terrors, and had learned to hail its coming with delight. The pathway of the sun and moon among the stars had been scanned and studied, until their slowest changes had been marked and measured.
Such were the rich fruits of diligence and persever ance which descended from the remote nations of antiquity. With the advantage of these great dis coveries, and the experience of preceding ages, it is natural to expect rapid progress, when science found its home among the bold, subtle, and inquisitive Greeks. He who entertains this expectation will meet with disappointment. Not that investigations were less constantly or perseveringly conducted,-not that less perfect means were employed, or less powerful talent consecrated to the work; but because a point had been reached of exceeding difficulty. The era of discovery from mere inspection was rapidly drawing to a close. It was an easy matter to count the days from full moon to full moon, to watch a planet as it circled the heavens, from a fixed star until it returned to the same star again, to mark its stopping, its reversed motion, and its onward goings; but it was a far different matter to rise to a knowledge of the causes of these stations and retrogradations, and to. render a clear and satisfactory account of them The
problem now presented, was to combine all the facts treasured by antiquity, all the movements exhibited in the heavens, and reduce them to simplicity and harmony. The Greek philosophers, from Plato down
the extinction of the last school of philosophy, recognized this to be the true problem, and essayed its solution, with an energy and pertinacity worthy of the highest admiration.
Let us now examine the causes which arrested the progress of astronomical discovery and held back the mind for a period of more than two thousand years. Surrounded as we are by the full blaze of truth, accustomed to the simplicity and beauty which now reign every where in the heavens, we find it next to impossible to realize the true position of those brave minds, which, enveloped in darkness, deceived by the senses, fettered by prejudice, struggled on and finally won the victory, whose fruits we enjoy.
The most careful and philosophical examination of the heavens seemed to lead to the admitted truth, that the earth was the centre of all celestial motion. In the configuration of the bright stars there was no change. From age to age, from century to century, immovably fixed in their relative positions, they had performed their diurnal revolutions around the earth. They were ever of the same magnitude, of the same brilliancy. How impossible was this, on any hypothesls, except that of the fixed central position of the earth. Leaving the fixed stars, an examination of the motions of the sun and moon-their nearly uniform velocity—their invariable diameters in all portions of their orbits, demonstrated the central position of the earth with reference to them. To shake a faith this
firmly fixed, sustained by the evidence of the senses, consonant with every feeling of the mind, accordant with fact and reason, required a depth of research, and the development of new truths, only to be revealed after centuries of observation.
Every effort, then, to explain the celestial phenomena, started with the undoubted fact, that the earth was the centre of all motion. Thus far, the mind had not reached the idea of apparent motion. If the moon moved, so equally did the sun. There was exactly the same amount of evidence to demonstrate the reality of the one motion, as the other ; neither were doubted. It would have been unphilosophical to reject the one, without rejecting the other.
The centre of motion once determined, the nature of the curve described was so obviously presented to the eye, that it seemed impossible to hesitate for one moment. The circle was the only regular curve known to the ancients. Its simplicity, its beauty and perfection, would have induced its selection, even had there been a multitude of curves from which to choose. Its curvature was ever the same. It had neither beginning nor end. It was the symbol of eternity, and admirably shadowed forth the eternity of the motions to which it gave form. As if these considerations had required confirmation, every star and planet, the sun and moon, all described circles, in their diurnal revolution, and it seemed impossible to doubt that their orbitual motions were performed in the same beautiful curve. In truth, observation confirmed this con jecture; and the orbits of all the moving bodies, when projected on the concave heavens, were circles. That this curve, then, should have been adopted without
doubt or hesitation, is not to be wondered at. It came therefore, to be a fixed principle, that in all hypotheses devised to explain the phenomena of the heavens, circular motion and circular orbits, alone could be employed.
To these great principles, of the central position of the earth, and the circular orbits, we must add that of the earth's immobility. This doctrine was undoubtedly sustained by the evidence of all the senses which could give testimony. No one had seen it move,had heard it move—had felt it move. How was it possible to doubt the evidence of the eye, the touch, the ear? Here, then, was another incontrovertible fact, which even the most skeptical could not doubt, and which laid at the foundation of all effort to resolve the problem under examination.
With a full knowledge and appreciation of these facts, we are prepared to enter upon an examination of the career of astronomy, up to the time when all darkness disappeared before the dawning of a day which should never end. The early Greek philosophers, little fitted by nature for close and laborious observation, rather chose to gather in travel the wisdom· which was garnered up in the temples, and among the priests of Egypt, and India. Returning to their native country, they theorised on the facts they had learned, and taught doctrines, which found their only support in trains of fanciful or specious reasoning. Thus we find Pythagoras mingling the great discoveries of antiquity with theories the most vague and visionary. While gleams of truth flash occasionally through the darkness of his doctrines, they seem but fortunate guesses. His views were sustained by