8 SIMON NEWCOMB— CAMPBELL. mwiol *v££™vn, 



unpublished observations was evident. The solar eclipse of December, 1870, took Newcomb to 

 Gibraltar, and, as soon as the siege of Paris was raised he instituted an exhaustive search for 

 unpublished occupations amongst the records of the Paris Observatory, with results beyond 

 his liveliest expectations. The observations that he wanted had been made in great numbers 

 both at the Paris Observatory and at other points in the city of Paris. The work of copying 

 the observational data, and of familiarizing himself with the methods of the astronomers in 

 making them, consumed six weeks. Newcomb estimates the value of these observations thus : 

 "The material I carried away proved the greatest find I ever made. Three or four years were 

 spent in making all the calculations * * *. Seventy-five years were added, at a single 

 step, to the period during which the history of the moon's motion could be written. Previously 

 this history was supposed to commence with the observations of Bradley, at Greenwich, about 

 1750; now it was extended back to 1675, and with a less degree of accuracy 30 years fur- 

 ther still. Hansen's tables were found to deviate from the truth, in 1675 and subsequent 

 years, to a surprising extent. * * * During the time I was doing this work, Paris was 

 under the reign of the Commune and besieged by the national forces. The studies had to be 

 made within hearing of the besieging guns." The results of the investigations were published 5 

 by Newcomb in 1878 



President Eliot, of Harvard College, offered the directorship of the Harvard College Ob- 

 servatory to Prof. Newcomb in 1875. After due consideration the offer was declined, because, in 

 his opinion, he was better fitted to conduct the work already started in Washington than to 

 direct an observing institution; and there was the further factor that the position of superin- 

 tendent of the American Ephemeris and the Nautical Almanac would become vacant auto- 

 matically in two years, and here, as Newcomb expressed it, "would be an unequaled oppor- 

 tunity for carrying on the work in mathematical astronomy I had most at heart." Newcomb 

 has further commented that "no one who knows what the Cambridge Observatory has become 

 under Prof. Pickering can feel that Harvard has any cause to regret my decision." 



In due time Prof. Newcomb was appointed Superintendent of the Nautical Almanac. 

 He assumed this duty on September 15, 1877. "The change was one of the happiest of my 

 life. I was now in a position of recognized responsibility, * * * where I could make 

 plans with the assurance of being able to carry them out * * *. The program of work 

 which I mapped out, involved, as one branch of it, a discussion of all the observations of value 

 on the positions of the sun, moon, and planets, and incidentally on the bright fixed stars, 

 made at the leading observatories of the world since 1750. One might almost say it involved 

 repeating, in a space of 10 or 15 years, an important part of the world's work in astronomy 

 for more than a century past. Of course, this was impossible to carry out in all its complete- 

 ness. In most cases what I was obliged practically to confine myself to was a correction of 

 the reductions already made and published. Stfil, the job was one with which I do not think 

 any astronomical one ever before attempted by a single person could compare in extent. The 

 number of meridian observations on the sun, Mercury, Venus, and Mars alone numbered 62,030. 

 They were made at the observatories of Greenwich, Paris, Konigsberg, Poulkovo, Cape of Good 

 Hope, but I need not go over the entire list, which numbers 13. The other branches of the work 

 were such as I have already described — the computation of the formulae for the perturbation 

 of the various planets by each other." A fuller and splendid statement of the nature of the 

 great problem, a report of progress made to date, and an outline of plans ahead, were pub- 

 lished by Newcomb in September, 1882, in Astronomical Papers of the American Ephemeris 

 and Nautical Almanac, 1, VII-XIV, 1882. 



Such enormous tasks could not, of course, be performed by any individual unaided. In 

 the introduction to the volume just referred to Newcomb wrote: "Both Congress and the 

 Navy Department have supplied all the assistance which has been asked for, and a force of 

 from eight to ten computers, some of the highest order of mathematical ability, has been actively 

 employed during the past year, and may, if necessary, be increased in the future." In his 



6 Researches on the Motion of the Moon. Part I: Reduction and Discussion of Observations of the Moon before 1750. Washington Observations for 

 1S75, Appendix II, pp. 1-280. 1878. 



