The New International Encyclopædia/Tschirnhausen, Ehrenfried Walter, Count
TSCHIRNHAUSEN, chḗrn'hou-zen, Ehrenfried Walter, Count (1651-1708). A German scientist and mathematician. He was born and educated at Leyden. He traveled considerably in France, Italy, and Switzerland, and served in the army of Holland (1672-73). Tschirnhausen erected large glass works in Saxony, where he constructed burning glasses of unusual perfection and carried on his experiments (1687-88). To him are due some valuable discoveries in the manufacture of porcelain. His Medicina Mentis (1687) testifies to the philosophic tendency of his thought. In mathematics Tschirnhausen is known as the founder of the theory of catacaustics, or caustics by reflection. The original articles appeared in the Acta Eruditorum from 1682 to 1698. These publications contain also his work on equations and quadratics. In connection with the latter he invented the quadratrix (see Quadrature) known by his name. Consult Weissenborn, Lebensbeschreibung des Tschirnhausen (Eisenach, 1866).