One of his first duties at Washington was to supervise the construction of the great 26-inch equatorial just authorized by Congress and to plan for mounting and housing it. In 1877 he became senior professor of mathematics in the navy, and from that time until his retirement as a Rear Admiral in 1897 he had charge of the Nautical Almanac office, with its large corps of naval and civilian assistants, in Washington and elsewhere. In 1884 he also assumed the chair of mathematics and astronomy in Johns Hopkins University, Baltimore, and he had much to to do, in an advisory capacity, with the equipment of the Lick Observatory and with testing and mounting its great telescope, at that time the largest in the world.
To enumerate his degrees, scientific honors, and medals would tire the reader. Among them were the degree of LL.D. from all the foremost universities, the gold medal of the Royal Astronomical Society of London in 1874, the great gold Huygens medal of the University of Leyden, awarded only once in twenty years, in 1878, and the Schubert gold medal of the Imperial Academy of St. Petersburg. The collection of portraits of famous astronomers at the Observatory of Pulkowa contains his picture, painted by order of the Russian Government in 1887. He was, of course, a member of many scientific societies, at home and abroad, and was elected in 1869 to our own National Academy of Sciences, becoming its vice-president in 1883. In 1893 he was chosen one of the eight foreign associates of the Institute of France,—the first native American since Benjamin Franklin to be so chosen. Newcomb’s most famous work as an astronomer,—that which gained him world-wide fame among his brother astronomers,—was, as has been said, too mathematical and technical to appeal to the general public among his countrymen, who have had to take his greatness, in this regard, on trust. They have known him at first hand chiefly as author or editor of popular works such as his “Popular Astronomy” (1877); of his text-books on astronomy, algebra, geometry, trigonometry, and calculus; of his books on political economy, which science he was accustomed to call his “recreation”; and of magazine articles on all sorts of subjects not omitting “psychical research,” which was one of the numerous by-paths into which he strayed. He held at one time the presidency of the American Society for Psychical Research.
The technical nature of his work in mathematical astronomy,—his “profession,” as he called it, in distinction to his “recreations” and minor scientific amusements,—may be seen from the titles of one or two of his papers: “On the Secular Variations and Mutual Relations of the Orbits of the Asteroids” (1860); “Investigation of the Orbit of Neptune, with General Tables of Its Motion” (1867); “Researches on the Motion of the Moon” (1876); and so on. Of this work Professor Newcomb himself says, in his “Reminiscences of an Astronomer” (Boston, 1903), that it all tended toward one result,—the solution of what he calls “the great problem of exact astronomy,” the theoretical explanation of the observed motions of the heavenly bodies.
If the universe consisted of but two bodies,—say, the sun and a planet,—the motion would be simplicity itself; the planet would describe an exact ellipse about the sun, and this orbit would never change in form, size, or position. With the addition of only one more body, the problem at once becomes so much more difficult as to be practically insoluble; indeed, the “problem of the three bodies” has been attacked by astronomers for years without the discovery of any general formula to express the resulting motions. For the actually existing system of many planets with their satellites and countless asteroids, only an approximation is possible. The actual motions as observed and measured from year to year are most complex. Can these be completely accounted for by the mutual attractions of the bodies, according to the law of gravitation as enunciated by Sir Isaac Newton? In Newcomb’s words, “Does any world move otherwise than as it is attracted by other worlds?” Of course, Newcomb has not been the only astronomer at work on this problem, but it has been his life-work and his contributions to its solution have been very noteworthy.
It is difficult to make the ordinary reader understand the obstacles in the way of such a determination as this. Its two elements are, of course, the mapping out of the lines in which the bodies concerned actually do move and the calculations of the orbits in which they ought to move, if the accepted laws of planetary motion are true. The first involves the study of thousands of observations made during long years by different men in far distant lands, the discussion of their probable errors, and their reduction to a common standard. The latter requires the use of the most refined methods of mathematical analysis; it is, as Newcomb says, “of a complexity beyond the powers of ordinary conception.” In works on celestial mechanics a single formula may fill a whole chapter.
This problem first attracted Newcomb’s attention when a young man at Cambridge, when by analysis of the motions of the asteroids he showed that the orbits of these minor planets had not, for several hundred thousand years past, intersected at a single point, and that they could not, therefore, have resulted, during that period, from the explosion of a single large body, as had been supposed.
Later, when Newcomb’s investigations along this line had extended to the major planets and their satellites, a curious anomaly in the moon’s motion made it necessary for him to look for possible observations made long before those hitherto recorded. The accepted tables were based on observations extending back as far as 1750, but Newcomb, by searching the archives of European observatories, succeeded in discovering data taken as early as 1660, not, of course, with such an investigation as this in view, but chiefly out of pure scientific curiosity. The reduction of such observations, especially as the old French astronomers used apparent time, which was frequently in error by quarter of an hour or so, was a matter of great difficulty. The ancient observer, having no idea of the use that was to be made of his work, had supplied no facilities for interpreting it, and “much comparison and examination was necessary to find out what sort of an instrument was used, how the observations were made, and how they should be utilized for the required purpose.” The result was a vastly more accurate lunar theory than had formerly been obtained.
During the period when Newcomb was working among the old papers of the Paris Observatory, the city, then in possession of the Communists, was beset by the national forces, and his studies were made within hearing of the heavy siege guns, whose flash he could even see by glancing through his window.
Newcomb’s appointment as head of the Nautical Almanac office greatly facilitated his work on the various phases of this problem of planetary motions. Their solution was here a legitimate part of the routine work of the office, and he had the aid of able assistants,—such men as G.W. Hill, who worked out a large part of the theory of Jupiter and Saturn, and Cleveland Keith, who died in 1896, just as the final results of his work were being combined. In connection with this work Professor Newcomb strongly advocated the unification of the world’s time by the adoption of an international meridian, and also international agreement upon a uniform system of data for all computations relating to the fixed stars. The former still hangs fire, owing to mistaken “patriotism”; the latter was adopted at an international conference held in Paris in 1896, but after it had been carried into effect in our own Nautical Almanac, professional jealousies brought about a modification of the plan that relegated the improved and modernized data to an appendix.
Professor Newcomb’s retirement from active service made the continuance of his great work on an adequate scale somewhat problematical, and his data on the moon’s motion were laid aside for a time until a grant from the newly organized Carnegie Institution in 1903 enabled him to employ the necessary assistance, and the work has since gone forward to completion.