SIMON NEWCOMB."

[With 1 plate.]

By ORMOND STONE.

Simon Newcomb was a unique figure in American science. Perhaps no other great American scientist was so many sided, no other, who approached him in versatility, stood at or so near the head in various departments of science. He was mathematician; celestial mechanician; astronomical observer, computer, and statistician; fundamental star cataloguer; author of memoirs on the lunar theory, of planetary tables, of books on popular astronomy, of mathematical school and college texts, of books on economics; novelist; president of a society for psychical research!

Simon Newcomb was born March 12, 1835, in Wallace, a village of Nova Scotia, but he was of New England descent. At the age of 17 he went to Salem, Massachusetts, and later to Maryland, where he taught school for several years. When 22 he became assistant in the Nautical Almanac office, then located at Cambridge, Massachusetts, and also a student in the Lawrence Scientific School, where he later graduated as bachelor of science. At the age of 25 he received an appointment as professor of mathematics, United States Navy, and was assigned to duty in the Naval Observatory in Washington. Sixteen years later he was placed in charge of the Nautical Almanac office, which had been removed to Washington, and of which he remained director from 1877 until 1897, when, having reached the age of 62, he was placed on the retired list. He continued to reside in Washington until he died, July 12, 1909. Upon the death of Professor Winlock, in 1875, he was offered but declined the directorship of the Harvard Observatory. From 1884 to 1894 to his duties in the

"Reprinted by permission from Astrophysical Journal, vol. 30, No. 3, October,

1909.

The portrait of Professor Newcomb, reproduced herewith, is from a photograph made in 1897 by Mr. A. D. Wyatt, of Brattleboro, Vermont. It therefore represents Professor Newcomb at the age of 62, in the year of his retirement from active service in the Navy Department.-EDS.

Nautical Almanac office he added those of professor of mathematics and astronomy at the Johns Hopkins University and editor of the American Journal of Mathematics. In what follows no attempt will be made to give more than the briefest outline of the more important of his astronomical activities.

The first work that called attention to his genius for research was carried out in Cambridge while he was an assistant in the Nautical Almanac office there. The final results were communicated in 1860 to the American Academy of Arts and Sciences in a paper showing, among other things, that so far as present theory could determine, the orbits of the asteroids had never passed through any common point of intersection. There was thus no evidence that these little planets were fragments of a larger planet which had suffered a cataclysm at some epoch in the distant past, as suggested by Olbers.

In 1862 the 8-inch transit circle of the Naval Observatory was received and placed in charge of Professor Newcomb, who proceeded to observe the stars of the American Ephemeris and other miscellaneous stars. During 1866 and 1867 the observing programme was so arranged that as far as possible groups of stars were observed about twelve hours apart in order to determine the systematic errors of the star places given in the Ephemeris, and thus obtain results. independent of previous observers. In the volume of Washington observations for 1870 Professor Newcomb published a memoir on the right ascensions of the equatorial fundamental stars and the corrections necessary to reduce the right ascensions of different star catalogues to a mean homogeneous system. In the first volume of the Astronomical Papers of the American Ephemeris, a magnificent series of volumes founded by Professor Newcomb and continued by him during his directorship of the Nautical Almanac office, he published another fundamental catalogue, this time giving both right ascensions. and declinations, derived from all the data then available, as had been the catalogue previously mentioned. And finally, in the eighth volume, is given a new determination of the precessional constant and a catalogue of fundamental stars for the epochs 1875 and 1900, reduced to an absolute system. This catalogue contains no less than 1,596 stars and is a masterpiece of exhaustive research. The positions given are likely to remain the standard for some time to come, probably at least until the observations of Piazzi, Maskelyne, Bessel, and Pond have been re-reduced. They have already been introduced into the principal national ephemerides of the world.

Professor Newcomb at an early date became interested in the question of the sun's parallax, and in 1869 published an investigation based upon all the data then available. The result at once became the standard and so remained for many years. Later, as a member of the Transit of Venus Commission, he took an active part in pre

paring for and directing the expeditions sent by the United States to various parts of the world to observe the transits of Venus that occurred in 1874 and 1882. Still later he made a careful study of the transits of 1761 and 1769, obtaining results agreeing well with those obtained from more modern observations. In connection with this investigation, after examining the original records, he vindicated the honesty of the much-maligned Father Hell, who was one of the principal observers of the transit of 1761 and was afterwards accused of "cooking" his observations. The importance of the velocity of light as a means of determining the sun's distance caused him to become interested in Michelson's experiments, and led him to make similar experiments himself. The acurracy secured far exceeded that of values previously obtained. Professor Newcomb's discussion of all the determinations of solar parallax given in the supplement to the American Ephemeris for 1897 may be considered the last word on the subject up to the present time.

In 1865 Professor Newcomb published an investigation of the orbit of Neptune, including tables of its motions. A similar treatise on the motions of Uranus was published in 1873. Both of these memoirs appeared in the Smithsonian Contributions to Knowledge. Having thus begun the study of the motions of the solar system, on taking charge of the Nautical Almanac office, he "deemed it advisable to devote all the force which he could spare to the work of deriving improved values of the fundamental elements and embodying them in new tables of celestial motions." This gigantic purpose he lived to see completed so far as the major planets were concerned. As the orbits of Neptune and Uranus were the first to receive his consideration, so the tables of these planets based upon newly revised theories were his last contribution to the Astronomical Papers before his retirement from the Nautical Almanac office.

For the solution of the problem of their motions the major planets were separated into three divisions: (1) The four inner planets; (2) Jupiter and Saturn; (3) Uranus and Neptune. Reserving for his own consideration the four inner and the two outer planets, he assigned the orbits of Jupiter and Saturn to Dr. G. W. Hill, stipulating merely that care be taken to make the work of the latter homogeneous with the work on the other major planets; for instance, the values of the masses of Jupiter and Saturn to be used were to be assigned by Professor Newcomb. In order to obtain an accurate determination of the mass of Jupiter, a careful study was made of the motions of the asteroid Polyhymnia, the eccentricity and major axis of whose orbit are so large that at times it approaches so near to Jupiter as to give rise to large perturbations.

As a supplement to the American Ephemeris for 1897, Professor Newcomb published a brief summary entitled "The Elements of the