THOMAS**, an eminent mathematician, was born at Oxford in 1560. Having been instructed in grammar, he entered St Mary Hall as a commoner, and took his bachelor's degree in 1579. He then distinguished himself by his skill in the mathematics, and became preceptor in that science to Sir Walter Raleigh. In 1585, he accompanied the first colony sent out to Virginia; and having surveyed that country, ascertained its natural productions, and observed the manners and customs of the aboriginal population, he published an account of it, which was afterwards reprinted in Hackluyt's *Voyages*. On his return to England, after an absence of two years, he resumed his mathematical studies with such zeal and success, that Henry earl of Northumberland, the liberal and enlightened protector of the learned, assigned him a yearly pension of L120. The same nobleman also pensioned Robert Hues, known by his Treatise on the Globes, and Walter Warner, who is supposed to have communicated to Harvey the first hint concerning the circulation of the blood. Both these persons were mathematicians; and, in 1608, when the earl was committed to the Tower for life, they, along with Harriot, were his constant companions, and usually styled his magicians. They had a table at the charge of the earl, who constantly conversed with them, to beguile the tedium of his confinement, as did also Sir Walter Raleigh, who was then a prisoner in the Tower. Harriot lived for some time at Sion College, and died at London on the 3rd of July 1621, at the age of sixty, after having suffered much from a cancer in the lip, occasioned by a habit he had contracted of holding in his mouth instruments of brass often charged with verdigris. He was universally esteemed on account of his learning. A manuscript of his entitled *Ephemeris Chrysometria* is preserved in Sion College; and his *Artis Analyticae Praxis ad Aequationes Algebraicas resolvendas* was published at London in 1631, folio. Descartes has been charged with taking from this book many improvements in algebra, which he afterwards published to the world as his own; but notwithstanding all that has been said by Wallis in his account of the discoveries of Harriot, and by Zach in the Astronomical Ephemeris for 1688, there seems to be no good ground for the charge; and it would even appear that much that incontestibly belongs to Viete or Descartes has been ascribed to Harriot. Montucla has reduced to their just value the services of the English mathematician, and shown that these, when truly estimated, are sufficiently important to entitle him to a place, in the second rank, amongst those men who have contributed to the progress of the mathematical sciences. (See Dissertations Third and Fourth, prefixed to this work). From some papers of Harriot, discovered in 1784, it appears that he had either procured a telescope from Holland, or divined the construction of that instrument; and that he coincided, in point of time, with Galileo in discovering the spots on the sun's disc. (A.)