SKETCH OF PROFESSOR BENJAMIN PEIRCE. 693 



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 high- 

 est honor ; but because there were, in fact, two very different solutions 

 of the perturbations of Uranus possible : Leverrier had correctly cal- 

 culated 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 show- 

 ing 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. /i 



" 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 sat- 

 ellites could not sustain a solid ring, but that sufficiently large and 

 numerous satellites could sustain a fluid ring, and that the actual sat- 

 ellites 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, par- . 

 ticularly in the lunar tables which he furnished, in his treatment of 

 Neptune, and various methods of computation. He also assisted Pro- 

 fessor Bache in the Coast Survey, and was, for many years, of great 

 service in that important national work before he was himself appoint- 

 ed 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 valu- 

 able extension of the law of probabilities to its own correction. His 

 detection of the mental error of lurking personal preferences for indi- 

 vidual 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 some- 

 times hold good to-day the really great man shows himself great by 

 any and every standard. The Coast Survey has, since the year 1845, 



