DAVIDSON, George, astronomer, born in Nottingham, England, 9 May 1825. He came to the United States in 1832, and was graduated at the Central high school in Philadelphia in 1845, standing first in his class. While a student he had shown interest in scientific work, and had assisted Alexander D. Bathe in his observations of the magnetic elements at Girard College. On his graduation he became the secretary of Professor Bathe, who had been appointed superintendent of the coast-survey. In 1846-'50 he was occupied in geodetic fieldwork, and in astronomy, serving in the different eastern states. In 1850 he went to California under the auspices of the coast-survey, and was for several years engaged in the determination of the latitude and longitude of prominent capes, bays, etc., and of the magnetic elements of the Pacific coast, reporting also upon the proper locations for lighthouses. His work included a survey of Washington and Puget sounds, and he had charge of the main triangulation of the coast in the region of San Francisco. From 1861 till 1867 he was on I the Atlantic seaboard, principally engaged in engineering work on coast and River de-fences. At one time he was in command of the coast-survey steamer "' Vixen," and-later performed astronomical work along the eastern coast. In 1866 he became chief engineer of an expedition for the survey of a ship-canal across the isthmus of Darien, and, in 1867, was appointed to make a special examination and report upon the geography and resources of Alaska, pending its purchase; and his published report and conferences with congressional committees influenced the passage of the bill. He was placed in charge, during 1867, of the work of the coast-survey on the Pacific, planned work for the land parties from 1868 till 1875, and inspected all the fields of work. From 1876 till 1886 he had charge of the main triangulation and astronomical work on the western coast ; and the records of the computing division show that the results of his observations stand higher than any ever executed in America, Europe, or India, and they have been characterized as "unique in the history of geodesy." In 1881 he measured the Yolo base line, the longest yet attempted in trigonometrical operations, and the system of triangulation directly connected therewith is called in his honor the "Davidson quadrilaterals." He founded the Davidson observatory in San Francisco, which was the first astronomical observatory on the Pacific coast of North America, and in 1869 brought the Pacific geodetic of the coast survey in telegraphic longitude connection with Greenwich. His astronomical work includes the observation of the total solar eclipse under the 60th parallel, in 1869; determination of the 120th meridian in 1873; charge of the U. S. transit of Venus expedition, in 1874; recovery of the transit of Venus station of 1769 in Lower California occupied by Auteroche de la Chappe; observation of the total sober eclipse of 7 January 1880; and in 1882 charge of the party to observe the transit of Venus in New Mexico. He holds the honorary chair of geodesy and astronomy in the University of California, and was a regent of that institution from 1877 till 1884. Professor Davidson has been appointed on many important government commissions, and in such capacity has made valuable reports to the departments. He is a member of numerous scientific societies, and has been president of the Geographical society of the Pacific states since 1881, and of the California academy of sciences front 1871 till 1886. In 1874 he was elected to the National academy of sciences. His publications, besides numerous papers contributed to the California academy of sciences, are principally special reports contained in government publications, and the "Coast Pilot of California, Oregon, and Washington "(1857-'87) and the "Coast Pilot of Alaska" (Part I., 1868).--His brother, Thomas, naval constructor, born in Nottingham, England, 28 August 1828; died in Philadelphia, Pennsylvania, 18 February 1874, came to the United States. at the age of four years, with his parents, who settled in Philadelphia. He early developed a talent for mechanical invention and construction, in consequence of which he was apprenticed to the trade of shipbuilding with Matthew Van Dusen, at the same time studying mathematics with his brother George. His capabilities soon attracted the attention of John Lenthall, then chief constructor of the U. S. navy. In 1850, when but twenty-two years old, he built his first vessel "from the stumps" on the banks of the James River, and soon afterward entered into business in Philadelphia. In 1861 he was appointed quartermaster over the ship-carpenters in the Philadelphia navy yard, and in 1.86;I was promoted to assistant naval constructor. He attained the full grade in 1866, with the relative rank of commander, which office he held until his death. At one time during the civil war he was conducting the repairs, at the Philadelphia navy yard, of forty-two vessels, large and small, and also building several new ones. The "Tuscarora," sister ship of the " Kearsarge," was built under his direction in fifty-eight working days, and the " Miami " in twenty-seven days. But his greatest feat was the building, in seventy days, of the "Juniata " (1,240 tons, 7 guns)from the frame of a Florida live-oak frigate that had been seasoned for twenty-three years. Mr. David-son displayed his engineering abilities in the floating of the "Monongahela," which had been driven inland on the Island of Santa Cruz {luring the earthquake of 18 November 1867, and left stranded forty feet high. With a body of skilled men selected from the different navy yards, in a little over three months he succeeded in moving the ship sidewise to the water's edge, and thence for 2,500 feet over the coral-bed to deep water. Subsequently he was ordered on duty at the bureau of construction in Washington, and was busy with plans for develop-mg a navy of armored vessels, torpedo boats, and fast cruisers. The models and drawings for the first large torpedo boats built in New York were executed by him. He was about to be sent to Europe for an exhaustive study of foreign navies and navy yards, when his health failed.