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Page:Popular Science Monthly Volume 18.djvu/711

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SKETCH OF PROFESSOR BENJAMIN PEIRCE.

consequence of the request of Leverrier to Galle that he should search the zodiac, in the neighborhood of longitude 325,° for a theoretical cause of certain perturbations of Uranus. But Peirce showed that the discovery was a happy accident; not that Leverrier's calculations had not been exact, and wonderfully laborious, and deserving of the highest honor; but because there were, in fact, two very different solutions of the perturbations of Uranus possible: Leverrier had correctly calculated one, but the actual planet in the sky solved the other; and the actual planet and Leverrier's ideal one lay in the same direction from the earth only in 1846. Peirce's labors upon this problem, while showing him to be the peer of any astronomer, were in no way directed against Leverrier's fame as a mathematician; on the contrary, he testified in the strongest manner that he had examined and verified Leverrier's labors sufficiently to establish their marvelous accuracy and minuteness, as well as their herculean amount.

"A few years later, 1851 to 1855, Peirce published the remarkable results of his labors upon Saturn's rings. Professor G. P, Bond had seen the ring divide itself and reunite, and had thereby been led to show by computation from Laplace's formulae that the ring could not be solid. Upon this Peirce investigated the problem anew, and showed that the ring, if fluid, could not be sustained by the planet; that satellites could not sustain a solid ring, but that sufficiently large and numerous satellites could sustain a fluid ring, and that the actual satellites of Saturn are sufficient.

"In 1849 he was appointed consulting astronomer to the 'American Ephemeris and Nautical Almanac,' and rendered efficient service in bringing that publication to its condition of honorable authority, particularly in the lunar tables which he furnished, in his treatment of Neptune, and various methods of computation. He also assisted Professor Bache in the Coast Survey, and was, for many years, of great service in that important national work before he was himself appointed superintendent in 1867. His calculations of the occultations of the Pleiades were very laborious and exact, and furnished an accurate means of studying the form, both of the earth and her satellite. His criterion for rejecting doubtful observations is an ingenious and valuable extension of the law of probabilities to its own correction. His detection of the mental error of lurking personal preferences for individual digits is a curious specimen of that acuteness of observation which characterizes his own mind.

"He held the office of Superintendent of the Coast Survey from 1867 to 1874. Coming after such able men as Hassler and Bache, to an office which required not only familiarity with mathematics and physics, but also great knowledge of men and executive ability, he was not found wanting, but showed that the theory of the Stoics will sometimes hold good to-day—the really great man shows himself great by any and every standard. The Coast Survey has, since the year 1845,