WILLIAMSON, Robert Stockton, soldier, born in New York in 1824; died in San Francisco, California, 10 November, 1882. He was graduated at the United States military academy in 1848, assigned to the topographical engineers, and took part in various surveys on the Pacific coast till 1856, when he became 1st lieutenant. From that time till the civil war he was on the staff of the commanding general of the Department of the Pacific, and in charge of military roads in southern Oregon, with meteorological observations on that coast. On 6 August, 1861, he was promoted captain, and, after reconnoissances on the lower Potomac till March, 1862, he was chief topographical engineer in the operations in North Carolina, being brevetted major, 14 March, 1862, for services at New Berne, and lieutenant-colonel on 26 April for the siege of Fort Macon. He then served with the Army of the Potomac, of which he was chief topographical engineer, from 21 November till 21 December, 1862, and held that post in the Department of the Pacific from 9 February till 3 March, 1868, when he was transferred to the corps of engineers, in which he was made major on 7 May. Afterward he served on the Pacific coast as superintending engineer of various surveys of rivers, harbors, and sites for fortifications. On 22 February, 1869, he was promoted lieutenant-colonel. Colonel Williamson published " Report of a Reconnoissance and Survey in California in Connection with Explorations for a Railway Route to the Pacific " in vol. iii. of "Pacific Railway Re ports" (Washington, 1853)" " On the Use of the Barometer on Surveys and Reconnoissances" (New York, 1868)" and " Practical Tables in Meteorology and Hypsometry," being an "appendix to the foregoing (1869).