George Davidson, 1825–1911, American geographer and astronomer, b. England. From 1845 to 1895 he was on the staff of the U.S. Coast and Geodetic Survey. He charted (1850–60) the U.S. Pacific coast for navigation purposes and recorded the results in the Pacific Coast Pilot. From 1860 to 1866, Davidson surveyed the Delaware River and mapped the district around Philadelphia for fortifications. His survey (1867) of the Alaskan coast resulted in the government publication Coast Pilot of Alaska (1869 and later editions). From 1867 to 1887, Davidson was charged with work along the coast of W United States; he measured the base lines known as the Davidson quadrilaterals, the basis for the primary triangulation of the Pacific coast states. In San Fransisco he built (1879) the first observatory on the Pacific coast. He also headed U.S. expeditions to observe total solar eclipses and the transits of Venus and Mercury. His writings include The Tracks and Landfalls of Bering and Chirikof (1901), The Discovery of San Francisco Bay (1907), and Francis Drake on the Northwest Coast (1908).