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 completed one important section of the work projected by Newcomb in 1877.

Among Newcomb’s most notable achievements are his researches in connexion with the theory of the moon’s motion. His first work on this abstruse subject, entitled Théorie des perturbations de la lune, qui sont dues à l’action des planètes, is remarkable for the boldness of its conception, and constitutes an important addition to celestial dynamics. For some years after the publication of Hansen’s tables of the moon in 1857 it was generally believed that the theory of that body was at last complete, and that its motion could be predicted as accurately as that of the other heavenly bodies. Newcomb showed that this belief was unfounded, and that as a matter of fact the moon was falling rapidly behind the tabular positions. With the view of examining this question, he undertook the reduction of every observation made before 1750 which appeared to be worthy of confidence. In an elaborate memoir he showed that the ancient solar eclipses described by Herodotus, Thucydides, and others, which seemed to require an increased value of the secular acceleration of the moon’s mean motion to bring them into line with modern results, might safely be neglected, the ambiguity of the accounts in each case rendering uncertain either the totality of the eclipse or the place from which it was visible. In his investigation he employed the eclipses of the moon recorded in the Almagest, the Arabian eclipses between 800 and 1004, extracted from Caussin’s translation of Ibn Junis, the eclipses and occultations of Bullialdus, Gassendi, and Hevelius, of the French astronomers at Paris and St Petersburg, and of Flamsteed at Greenwich, and deduced a secular acceleration of 8·8″, agreeing well with the theoretical value.

On taking charge of the 26-in. equatorial at the United States Naval Observatory, Newcomb devoted it almost exclusively for the first two years to observations of the satellites of Uranus and Neptune, being of opinion that it was better to do one thing well than many things indifferently. The results of these skilfully conducted observations were published in a memoir on The Uranian and Neptunian Systems. From this research it appears that the orbits of all four satellites of Uranus are sensibly circular, and although no special search was made, he concludes that none of Sir William Herschel’s supposed outer satellites can have any real existence. From the motion of the satellites he finds that the mass of Uranus is th of that of the sun, while for the planet Neptune he finds a mass equal to th of the sun, agreeing with the value previously found by him from the perturbations of Uranus within th of its amount. As early as 1860 Newcomb communicated an important memoir to the American Academy, On the Secular Variations and Mutual Relation of the Orbits of the Asteroids, in which he discussed the two principal hypotheses to account for the origin of these bodies—one, that they are the shattered fragments of a single planet (Olbers’ hypothesis), the other, that they have been formed by the breaking up of a revolving ring of nebulous matter.

In the Astronomical Papers of the American Ephemeris will be found a large number of contributions from Newcomb’s pen on some fundamental and most important questions of astronomy. Among these are papers on The Recurrence of Solar Eclipses, A Transformation of Hansen’s Lunar Theory, Development of the Perturbative Function and its Derivatives. His memoir On the Motion of Hyperion, a New Case in Celestial Mechanics, is in some respects one of his most original researches. He discussed the transits of Venus of 1761 and 1769, and those of Mercury from 1677 to 1881. At the international conference, which met at Paris in 1896 for the purpose of elaborating a common system of constants and fundamental stars to be employed in the various national ephemerides, Newcomb took a leading part, and at its suggestion undertook the task of determining a definite value of the constant of precession, and of compiling a new catalogue of standard stars. The results of these investigations were published in 1899, and have been in use since the beginning of 1901. In the intervals of these immense labours, on which his reputation as an astronomer rests, he found leisure for works of a lighter character, e.g. his Popular Astronomy (1878) which has been translated into German, Russian, Norwegian, Czech, Dutch and Japanese, his Astronomy for Schools and Colleges (1880), written in conjunction with Professor E. S. Holden, and Astronomy for Everybody (1903). After his retirement from official life he published an excellent popular treatise on The Stars (1901). A more recondite work is his Compendium of Spherical Astronomy (1906). He also wrote on questions of finance and economics.

He received the honorary degrees of D.C.L. Oxford, and Sc. D. Cambridge and Dublin. In 1872 he was elected an associate of the Royal Astronomical Society, receiving its gold medal in 1874. In 1877 he was elected a foreign member of the Royal Society, which in 1890 awarded him the Copley medal. He also received the first Bruce medal of the Astronomical Society of the Pacific, awarded by the directors of the Berlin, Greenwich, Harvard, Lick, Paris and Yerkes observatories. Except Benjamin Franklin he was the only American to become an Associate of the French Institute. He died at Washington on the 11th of July 1909, and was given a military funeral, having been made a rear-admiral by Act of Congress in 1906.

 NEWCOMEN, MATTHEW (c. 1610–1669), English nonconformist divine, was born about 1610 and educated at St John’s College, Cambridge (M.A. 1633). In 1636 he became lecturer at Dedham in Essex, and was the leader of the church reform party in that county. He assisted the elder Calamy in writing Smectymnuus (1641), and preached before parliament in 1643. He was a man of many gifts, excelling alike in preaching, in debate and in friendship, and declined many offers of more remunerative service. He protested against the extreme democratic proposals called “The Agreement of the People” (1647), and was one of the commissioners at the Savoy Synod of 1658. On the passing of the Act of Uniformity in 1662, Newcomen lost his living, but was soon invited to the pastorate at Leiden, where he was held in high esteem not only by his own people but by the university professors. He died of the plague in 1669.

 NEWCOMEN, THOMAS (1663–1729), English engineer, one of the inventors of the steam-engine, was born at Dartmouth in 1663. While employed as an ironmonger in his native town, he corresponded with Robert Hooke about the previous investigations of Denis Papin and the marquis of Worcester as to the applicability of steam-power for the purpose of driving machinery, and in conjunction with John Calley (or Cawley), said to have been a grazier or glazier in Dartmouth, and Captain Thomas Savery (1650?–1715), a military engineer, he constructed in 1705 a “fire-engine,” now known as the “atmospheric steam-engine.” He died in 1729, probably in London. (See .)

 NEWDIGATE, SIR ROGER (1719–1806), English antiquary, was born on the 30th of May 1719. He was the 5th baronet of Harefield (in Middlesex) and Arbury (in Warwickshire), and grandson of Sir Richard Newdigate, an English chief justice during the time of Richard Cromwell’s protectorate. He was educated at University College, Oxford. From 1741 to 1747 he was M.P. for Middlesex, and from 1750 to 1780 M.P. for the university of Oxford. In 1753 he spoke in parliament on behalf of the repeal of the Plantation Act, and during the debates on the land tax in 1767 he opposed the duke of Grafton’s administration and the proposed grant to the royal princes. Being the owner of extensive collieries near Bedworth in Warwickshire, he actively promoted the Coventry, Oxford and Grand Junction canal, cutting also a canal from his collieries to Coventry, and interesting himself in the construction of the turnpike road from