Biographies of distinguished scientific men. First series

by F. Arago

This vast plan essentially led to the minute discussion and comparison of a multitude of passages both ancient and modern. If the author had mixed up these discussions with the body of the work, he would have laboured for astronomers only. If he had suppressed all discussions, the book would have interested amateurs only. To avoid this double rock, Bailly decided on writing a connected narrative with the quintessence of the facts, and to place the proofs and the discussions of the merely conjectural parts, under the appellation of explanations in separate chapters. Bailly's History, without forfeiting the character of a serious and erudite work, became accessible to the public in general, and contributed to disseminate accurate notions of Astronomy both among literary men and among general society.

When Bailly declared, in the beginning of his book, that he would go back to the very commencement of Astronomy, the reader might expect some pages of pure imagination. I know not, however, whether any body would have expected a chapter of the first volume to be entitled, Of Antediluvian Astronomy.

The principal conclusion to which Bailly comes, after an attentive examination of all the positive ideas that antiquity has bequeathed to us is, that we find rather the ruins than the elements of a science in the most ancient Astronomy of Chaldæa, of India, and of China.

After treating of certain ideas of Pluche, Bailly says, "The country of possibilities is immense, and although truth is contained therein, it is not often easy to distinguish it."

Words so reasonable would authorize me to inquire whether the calculations of our fellow-labourer, intended to establish the immense antiquity of the Indian Tables, are beyond all criticism. But the question has been sufficiently discussed in a passage of The Exposition of the System of the World, on which it would be useless to insist here. Whatever came from the pen of M. de Laplace was always marked by the stamp of reason and of evidence. In the first lines of his magnificent work, after having remarked that "the history of Astronomy forms an essential part of the history of the human mind," Bailly observes, "that it is perhaps the true measure of man's intelligence, and a proof of what he can do with time and genius." I shall allow myself to add, that no study offers to reflecting minds more striking or more curious relations.

When by measurements, in which the evidence of the method advances equally with the precision of the results, the volume of the earth is reduced to the millionth part of the volume of the sun; when the sun himself, transported to the region of the stars, takes up a very modest place among the thousands of millions of those bodies that the telescope has revealed to us; when the 38,000,000 of leagues which separate the earth from the sun, have become, by reason of their comparative smallness, a base totally insufficient for ascertaining the dimensions of the visible universe; when even the swiftness of the luminous rays (77,000 leagues per second) barely suffices for the common valuations of science; when, in short, by a chain of irresistible proofs, certain stars have retired to distances that light could not traverse in less than a million of years; we feel as if annihilated by such immensities. In assigning to man, and to the planet that he inhabits, so small a position in the material world, Astronomy seems really to have made progress only to humble us.

But if, on the other hand, we regard the subject from the opposite point of view, and reflect on the extreme feebleness of the natural means by the help of which so many great problems have been attacked and solved; if we consider that to obtain and measure the greater part of the quantities now forming the basis of astronomical computation, man has had greatly to improve the most delicate of his organs, to add immensely to the power of his eye; if we remark that it was not less requisite for him to discover methods adapted to measuring very long intervals of time, up to the precision of tenths of seconds; to combat against the most microscopic effects that constant variations of temperature produce in metals, and therefore in all instruments; to guard against the innumerable illusions that a cold or hot atmosphere, dry or humid, tranquil or agitated, impresses on the medium through which the observations have inevitably to be made; the feeble being resumes all his advantage; by the side of such wonderful labours of the mind, what signifies the weakness, the fragility of our body; what signify the dimensions of the planet, our residence, the grain of sand on which it has happened to us to appear for a few moments!

The thousands of questions on which Astronomy has thrown its dazzling light belong to two entirely distinct categories; some offered themselves naturally to the mind, and man had only to seek the means for solving them; others, according to the beautiful expression of Pliny, were enveloped in the majesty of nature! When Bailly lays down in his book these two kinds of problems, it is with the firmness, the depth, of a consummate astronomer; and when he shows their importance, their immensity, it is always with the talent of a writer of the highest order; it is sometimes with a bewitching eloquence. If in the beautiful work we are alluding to, Astronomy unavoidably assigns to man an imperceptible place in the material world, she assigns him, on the other hand, a vast share in the intellectual world. The writings which, supported by the invincible deductions of science, thus elevate man in his own eyes, will find grateful readers in all climes and times.

In 1775, Bailly sent the first volume of his history to Voltaire. In thanking him for his present, the illustrious old man addressed to the author one of those letters that he alone could write, in which flattering and enlivening sentences were combined without effort with high reasoning powers. "I have many thanks to return you, (said the Patriarch of Ferney,) for having on the same day received a large book on medicine and yours, while I was still ill; I have not opened the first, I have already read the second almost entirely, and feel better."

Voltaire, indeed, had read Bailly's work pen in hand, and he proposed to the illustrious astronomer some queries, which proved both his infinite perspicacity, and wonderful variety of knowledge. Bailly then felt the necessity of developing some ideas which in his History of Ancient Astronomy were only accessories to his principal subject. This was the object of the volume that he published in 1776, under the title of Letters on the Origin of the Sciences and of the People of Asia, addressed to M. de Voltaire. The author modestly announced that "to lead the reader by the interest of the style to the interest of the question discussed," he would place at the head of his work three letters from the author of Merope, and he protested against the idea that he had been induced to play with paradoxes.