Thomas Sydenham, an English physician, born at Winford Eagle, Dorsetshire, in 1G24, died in London, Dec. 29, 1689. He graduated at Oxford, and in 1648 obtained a fellowship in All Souls' college, and studied there some years, visiting France in the mean while and attending the lectures of Barbeyrac. About 1660 he went to Westminster, and soon obtained a large practice and great reputation. Abandoning the routine system then in vogue, he based his practice on principles which recognize that there is in the human system a recuperative power, the vis medicatrix naturae, and that this should be aided, not thwarted. He was the first who treated smallpox with cooling remedies, or intermittent fever with cinchona. The preparation known as Sydenham's laudanum was one of many valuable additions which he made to the materia med-ica. A collective edition of his works in Latin was published in London in 1785 (English translation, 1696). - In 1843 a society, composed mainly of members of the medical profession, was founded in London under the name of the Sydenham society, having for its object the republication of the works of Sydenham and of other eminent physicians of former times, otherwise inaccessible to professional readers in general, and published his works translated from the Latin by P. G. Latham (2 vols., London, 1848-'50).