COMSTOCK, CYRUS BALLOU ( 1831—). An American soldier and military engineer. He was born in West Wrentham, Mass., graduated at West Point in 1855, was appointed lieutenant engineer, and from 1859 to 1861 was assistant professor of natural and experimental philosophy at the Military Academy. On the outbreak of the Civil War he was assigned to active duty as first lieutenant of engineers, and for some time was one of the assistant engineers engaged in the construction of defenses it Washington. He was assistant to the chief engineer of the Army of the Potomac from 'March to June, 1862; was senior engineer on General Summer's staff in .Tune and July; served as a member of the ewtineer battalion in the Maryland campaign; and from November, 1862, to March, 1863, was chief engineer of the Army of the Potomac. He was subsequently engaged in the siege of Vicks burg, was chief engineer of the Army of the Ten nessee from July to October, 1863; was assistant inspector-general of the Division of the :Missis sippi from November, 1863. to March. 1864; and
was senior aide-de-camp to General Grant from March, 1861, to July, 1866. At the close of the war 1w was brevetted major- general of volun teers and brigadier-general in the Regular Army, and from July. 1866. to May, 1870. was aide de-camp to the (letter:II-in-Chief, with rank for ,,et oral years he superintending engineer of the geodetic survey of the Northern and Northwestern lakes. and in addition has been engaged as Ini many important Government works. In he became colonel in the engineer corps, and was retired from act it e service in 18113. Bo has published: Notes on European Nn rows (187(i); Surrey of the NOrthireNtern Lakes (1877) ; and Primary Triangulation United ;slates Lal.e Surrey (1882).