JEFFERS, William Nicholson, naval officer, born in Gloucester county, New Jersey, 6 October, 1824; died in Washington, D. C., 23 July, 1883. He entered the navy as a midshipman, 25 September, 1840, took part in the capture of Upper California in 1842, and at the beginning of the Mexican war was ordered to the steamer "Vixen," and was present in all the naval actions in the Gulf of Mexico. He was promoted to master in June, 1854, and commissioned lieutenant in January, 1855, and while in command of the "Water Witch" rescued the Spanish steamer "Cartagena," for which service the queen of Spain presented him with a sword. He was also present at the engagement with the fort at Paso de la Patria, which caused the expedition under Commander Shubrick to Paraguay. At the beginning of the civil war he was on sick-leave at his home, but at once applied for service, and was detailed on ordnance duty at Norfolk. He commanded the "Philadelphia" on Potomac river in April and May, 1861, the "Underwriter" during the brilliant operations in the sounds of North Carolina during January and February, 1862, and the "Monitor" in the action with Fort Darling on 15 May of that year. He was commissioned commander in March, 1865, captain in July, 1870, and in April, 1873, became chief of the bureau of ordinance. He was made commodore, 26 February, 1878, and in 1875 introduced a system of bronze and steel boat howitzers. In 1876 he doubled the power of the Dahlgren 11-inch smooth-bore by converting it into an 8-inch rifle, and the details of a breach-loading system for every calibre up to 12-inch. He published "Short Methods in Navigation" (1849); "Theory and Practice of Naval Gunnery" (New York, 1850); "Inspection and Proof of Cannon" (1864); "Marine Surveying" (1871); "Ordinance Instructions for United States Navy" (1866, 1880), and numerous pamphlets on naval subjects.