STEVINUS, SIMON Dutch mathematician, was born in 1548 at Bruges and died in 162o at The Hague or in Leyden. He was director of the "waterstaet," and afterwards quartermaster-general. Stevinus was known to his contemporaries by his military methods and inventions; he invented defence by a system of sluices which was of great importance in the Nether lands. He also invented a carriage with sails which was used on the seashore and carried 26 passengers.
In his Statics and Hydrostatics (Leyden, 1586) he enunciated the important theorem of the triangle of forces. This gave a new impetus to the study of statics, which had previously been founded on the theory of the lever. He discovered the hydrostatic paradox that the downward pressure of a liquid is independent of the shape of the vessel, and depends only on its height and base.
In 1586 he published a pamphlet of a few pages, the French translation of which is entitled La Disme enseignant facilement expedier par Nombres Entiers sans rompuz tous Comptes se ren contrans aux Affaires des Hommes. In this he treated decimal
fractions. Decimal fractions and fractions had been employed for the extraction of square roots some five centuries before his time, but nobody before Stevinus established their daily use. He de clared the universal introduction of decimal coinage, measures and weights to be only a question of time. His notation is rather unwieldy. He printed little circles round the exponents of the different powers of one-tenth. For instance, was printed 237 © 5 0 7 ® 8 and the fact that Stevinus meant those encircled numerals to denote mere exponents is evident from his employing the same sign for powers of algebraic quantities, e.g., 9 ® — 140 + 6 ® --- 5 to denote —5.
A number of his writings were translated into Latin by W. Snellius. There are two complete editions in French of his works (Leyden, i6o8 and 1634) by Albert Girard. See Steichen, Vie et travaux de Simon Stevin (Brussels, 1846) ; M. Cantor, Geschichte der Mathematik.