From this brief account of the “Mécanique Céleste” you may judge of the difficulties which the original writer had to overcome in making it, and of the immense labor requisite. But La Place frequently supposes that a proposition is perfectly intelligible to his reader because it is so to him. Having such a powerful mind, he is able to see at a glance that for which any one else would require a long demonstration, before he could become thoroughly master of the subject. The consequence of this is, an obscurity in the work, which has made it doubly difficult of comprehension. Several years ago, but a long time after Dr. Bowditch had read and made notes upon the whole work, an English writer said that there were scarcely twelve men in Europe capable of comprehending it. Dr. Bowditch, feeling that it was the most valuable work upon astronomy published in modern times, had undertaken the translation of it, and had made notes thereupon, for the purpose of “amusing his leisure hours.” Upon its being known that he had finished the task, the American Academy offered to publish it. Dr. Bowditch would not allow this, and reserved the publication until he was able to do so at his own expense. Let us see, now, what service Dr. Bowditch intended to perform by his translation and commentary. His first object was to lay before America the greatest work on the science of astronomy ever published. Secondly, his aim was to bring that work down to the comprehension of young men, and students of mathematics, by filling up the places left by La Place without demonstration. Thirdly, he meant to give the history of the science of astronomy for the interval between the publication of the original work and that at which the translation appeared. Fourthly, he wished to collect together all the discoveries which he had made during the forty years of his life that he had devoted to science. His first aim was gained by the translation. His second was completely successful, for he was assured by correspondents, both in America and Europe, that he had enabled several to read the immortal work of La Place, who never would have done so had not Dr. Bowditch published his Commentary. The royal astronomer at Palermo says, in a printed work published after the first two volumes of the translation had reached him, “Bowditch’s Commentary should be translated into Italian;” and Lacroix, a celebrated French mathematician, advised a young Swiss to read La Place in the American edition rather than in the original. But what pleased the commentator more than anything else, were the frequent letters from young men residing in various parts of America, expressing gratitude for the benefits they had received from his work. When I think of these, I am reminded of the epithet bestowed upon Dr. Bowditch since his death, and by one well capable of judging, namely, “Father of American Mathematics.” He has given a tone to the study of science which will be long felt.
In regard to the third object, all critics allow that he was eminently successful in giving the history of science up to the time proposed.
Upon the fourth point, we might refer, first, to the immense increase of bulk of the work, as a proof, but I prefer to mention a few details; and in order to this, let us examine the Commentary, and let it speak for itself. But it must be remembered, that, in making this examination, I must omit many circumstances, because you would not understand or feel interested in any greater detail.
ERRORS IN IT.
PERMANENCE OF THE SOLAR SYSTEM.
ERROR IN PRINCIPIA.
In the first volume he points out two errors of La Place, one of which relates to the motion of the earth; and the other is of much importance. It relates to the permanency of our solar system, as it is commonly called. You all doubtless know that the sun is situated in the centre, and the planets, with our earth, revolve around this luminary, which gives light and heat to all. Now, these bodies revolve in certain fixed “nearly circular” directions, and La Place thought that they would always continue to do so, and that Mercury, Venus, the Earth, Mars, Jupiter, Saturn, and Herschel would forever continue to wheel around in their accustomed orbits. Dr. Bowditch proves, however, that though this may be true of the three larger planets,—Jupiter, Saturn, and Herschel,—it is not equally certain, from the proofs given by La Place, that our earth, or any of the other smaller planets, may not fly off into regions far remote from those in which they have been revolving for ages. This error had been made the subject of a paper to the American Academy at an earlier period of his life. But it must not be supposed that there is any proof that the solar system will not continue to exist for many long ages. On the contrary, there is no doubt that it will last millions of years. Dr. Bowditch merely wished to assert that La Place’s argument and calculation did not prove as much as the French mathematician thought they did. In this volume Dr. Bowditch likewise alludes to a topic which he had made the subject of a communication, a long time previously, to the American Academy; I refer to a mistake in Newton’s “Principia,” which he discovered when quite young, and had sent an account of to the president of Harvard College. This gentleman referred the question to the professor of mathematics, who believed the youth was mistaken. Doubtless he thought it very strange that a simple youth should presume to correct anything published by so eminent a man as Newton. The error of the professor will become less singular when you learn that the same mistake escaped the notice of all the commentators on the “Principia,”—that is, for more than a century,—and that the cause of the original communication being made to the Academy was the attempt of Mr. Emerson, an Englishman, to prove the correctness of the English philosopher. Every one, I believe, now allows that Dr. Bowditch was correct, and that a considerable error would result, in calculating the orbit of a comet, from using Newton’s calculations.