(Thomas), a celebrated algebraist, was born at Oxford in 1560, where he was also educated. In 1579, he completed his bachelor's degree; and, being already distinguished for his mathematical learning, was soon after recommended to Sir Walter Raleigh, Raleigh, as a proper person to instruct him in that science. He was accordingly received into the family of that gentleman; who, in 1585, sent him with the colony, under Sir Richard Grenville, to Virginia; of which country, having remained there about a year, he afterwards published a topographical description. About the year 1588, Mr Harriot was introduced by his patron Sir Walter Raleigh, to Henry Percy earl of Northumberland, who allowed him a pension of £20 per annum. He spent many years of his life in Sion college; where he died in July 1621, of a cancer in his lip, and was buried in the church of St Christopher, where a handsome monument was erected to his memory. Anthony Wood tells us, he was a deit, and that the divines looked upon his death as a judgment. Be his religious opinions what they might, he was doubtless one of the first mathematicians of the age in which he lived, and will always be remembered as the inventor of the present improved method of algebraical calculation. His improvements in algebra were adopted by Des Cartes, and for a considerable time imposed upon the French nation as his own invention; but the theft was at last detected, and exposed by Dr Wallis, in his History of Algebra, where the reader will find our author's invention accurately specified. His works are, 1. A brief and true report of the new-found land of Virginia; of the commodities there found, and to be raised, &c. 2. Artis analyticae practicae ad equationes algebraicas nova expedita, et generali methodo resolvendas, e psalmum Thomae Harriotti, &c. 3. Ephemeris chromatica. Manuscript, in the library of Sion college. He is said to have left several other manuscripts which are probably lost.