MAYO, William, civil engineer, born in England about 1685; died in Richmond, Virginia, 20 October, 1744. In 1716 he emigrated to the island of Barbadoes, of which he made an excellent survey between 1717 and 1721. His map is now on file in King's college library at Oxford. He went to Virginia in 1723, and in 1728, with Professor Alexander Irvin, he ran the dividing-line between Virginia and North Carolina. Colonel William Byrd, in his manuscript on this subject, says that a chaplain, the Reverend Peter Fountain, accompanied the surveying party, "that the people on the frontier of North Carolina might have an opportunity to have themselves and their children baptized." One of the rivers intersecting the line was named in honor of Major Mayo, and still retains the name, while the North Carolina commissioners presented him with a large tract of land. In 1737 he was appointed one of the surveyors to lay off the northern neck of Virginia in order to settle disputed boundaries between Lord Fairfax and the crown. The same year he laid out the city of Richmond. At the time of his death he was the chief civil engineer in Virginia.--His son, John, legislator, born in Virginia, 17 July, 1737; died in Richmond, Virginia, 15 February, 1780, was a member of the house of burgesses from Chesterfield county, Virginia, in 1769, 1770, and 1771, and from Henrico county in 1775. In 1.775-'6 he was a member of the Virginia state convention. --John's son, John, soldier, born in Richmond, Virginia, 21 October, 1760; died in Belleville, near Richmond, 28 May, 1818, was colonel of Virginia state troops during the war of 1812, and represented Henrico county in the legislature. In 1785 he obtained a charter for the Mayo bridge, which is situated just below the falls of James river at Richmond. The bridge is more than a quarter of a mile in length, and was built by Colonel Mayo from his own design and at his individual expense. From frequent destruction of the bridge by floods, once within twenty-four hours after its complete restoration, Colonel Mayo's patrimony was exhausted, and he was twice imprisoned within bounds for debt, but his indefatigable resolution overcame all obstacles, and success at last proved the practicability of his efforts. In the midst of his difficulties, Patrick Henry voluntarily submitted an unsuccessful proposition to the Virginia legislature to make a loan of public money to the "spirited proprietor." Colonel Mayo married Abigail De Hart, daughter of John De Hart, of Elizabethtown, who was a member of the first Continental congress that assembled at Philadelphia in 1774. Their eldest daughter, Maria, married General Winfield Scott.--William's grandson, Robert, author, born in Powhatan county, Virginia, 25 April, 1784 ; died in Washington, D. C., 31 October, 1864, was graduated at the medical department of the University of Pennsylvania in 1808, and practised in Richmond, Virginia During the presidential canvass of 1828 he edited at Richmond the "Jackson Democrat." In 1830 he entered the civil service of the government in Washington, where he remained till his death. He published "View of Ancient Geography and History" (Philadelphia, 1813); "New System of Mythology" (4 vols., 1815-'19) ; "Pension Laws of the United States, 1776-1833" (Washington, 1833 ; 2d ed., with F. Moulton, 1852) ; "Synopsis of the Commercial and Revenue System of the United States" (2 vols., 1847) ; and "The Treasury Department, its Origin, Organization, and Operations" (1847). He left uncompleted a genealogical history of the Mayo family of Virginia.--William's great-grandson, Joseph, lawyer, born in Fine Creek Mills, Powhatan County, Virginia, 16 November, 1795 ; died in Richmond, Virginia, 9 August, 1872, studied medicine in Philadelphia, but left it for law, attaining high rank in his profession. He was commonwealth attorney in Richmond from 1823 till 1853, a member of the legislature, and mayor of Richmond from 1853 till the occupation of the city by the United States forces in April, 1865. Mr. Mayo was the author of a "Guide to Magistrates," a standard authority (Richmond; 2d ed., revised, 1860).