AUTHORS: Achillini, Alessandro Agricola, Georgius Alberti, Leone Battista Archimedes Aristotle Babington, John Baif, Lazare de Baldi, Bernardino Baliani, Giovanni Battista Barocius, Franciscus Benedetti, Giovanni Battista Berga, Antonio Biancani, Giuseppe Borelli, Giovanni Alfonso Borro, Girolamo Boyle, Robert Branca, Giovanni Buonamici, Francesco Buteo, Johannes Cardano, Girolamo Casati, Paolo Castelli, Benedetto Cataneo, Girolamo Ceredi, Giuseppe Ceva, Giovanni Cicero, M. Tullius Commandino, Federico Delfino, Federico Descartes, Rene Epicurus Euclid Fabri, Honore Foscarini, Paolo Antonio Galilei, Galileo Gassendi, Pierre Ghetaldi, Marino Giphanius, Hubert Guevara, Giovanni di Heron Alexandrinus Heytesbury, William Hutton, Charles Jordanus de Nemore Landi, Bassiano Lorini, Buonaiuto Lucretius Manuzio, Paolo Marci of Kronland, Johannes Marcus Mellini, Domenico Mersenne, Marin Monantheuil, Henri de Monte, Guidobaldo del Morelli, Gregorio Newton, Isaac Pacioli, Luca Pappus Alexandrinus Salusbury, Thomas Santbech, Daniel Schott, Gaspar Schreck, Johann Terrenz Stelliola, Niccolò Antonio Stevin, Simon Tartaglia, Niccolò Thomaz, Alvaro Thucydides Torricelli, Evangelista Valerio, Luca Varro, Michel Vitruvius Pollio Wolff, Christian von 
Stevin, Simon, known as Simon de Bruges born in 1548 in Bruges, died between 202 and 1841620 in Den Haag, Flemish mathematician, engineer and architect Stevin was the illegitimate son of Antheunis Stevin and Cathelijne van de Poort, both of whom were extremely prosperous citizens of Bruges. Almost nothing is known of his early years; all that is certain is that he worked in the financial administration of Bruges and Antwerp. In the years between 1571 and 1577 he travelled widely, to Poland, Prussia and Norway, and lived from 1581 in Leyden, where he was admitted to the university in 1583 and chiefly studied mathematics. His religious affiliation is unknown; neither is it known whether he left the southern Netherlands during Spanish occupation because of religious persecution. Stevin was actively involved in organizing the Dutch War of Liberation against the Spaniards. From 1589 he was the tutor and confidante of Prince Moritz of Oranien, for whom he wrote several private textbooks and who made him (by 1593 at the latest) Superintendent of Agricultural and Hydraulic Structures in the Netherlands, later appointing him as General Quartermaster of the Netherlands Army in 1604. In these offices Stevin did great service for the artillery and for the construction of dykes and forts. In 1610 Stevin married Catherine Cray, with whom he had four children. His son Hedrick became a successful scientist himself and published several of his father’s manuscripts after Stevin’s death. Stevin was interested in a great number of different scientific areas, about which he wrote numerous books of his own, all of which were distinguished by a very clear and comprehensible style and most of which were written in Dutch. Many of these books are related to his responsibilities in the city administration and his associated economic tasks. In 1582 he published his first book, Tafelen van Interest, the first systematic depiction ever published of the method and the results of calculating interest and compound interest. This book also includes important tables on calculating discounts and interest, which up to that time had been kept secret by the bankers of the day, as there were very few people at the time who mastered discount and interest calculations. In De Thiende, a pamphlet of just 29 pages from the year 1585, Stevin introduces a generally applicable method for expressing decimal fractions and their application outside of the field of trigonometry, where they had already been used by J. Regiomontanus. Although Stevin did not yet use the conventional decimalpoint notation for decimal fractions, his arguments for their use were so convincing that decimal fractions soon found general acceptance. Repeatedly throughout his career, Stevin supported the cause of using decimal fractions of units of measure, weight and coinage. His L’arithmétique, which appeared in 1585, is a general outline of the arithmetic and algebra of the time. In contrast to his contemporaries, Stevin was of the opinion that all numbers, including square numbers, square roots, negative numbers and irrational numbers, are of the same nature and that it was possible to calculate with them in a uniform way. L’arithmétique was of great importance for the emergence of the modern concept of numbers. It was also in this tract that Stevin gave quite useful approximate solutions for seconddegree, thirddegree and fourthdegree equations. In a later edition of L’arithmétique he showed how to approximate a real root of an equation of any degree. In his two main works, De Beghinselen der Weeghconst and De Beghinselen des Waterwichts (The Rudiments of Statics, The Rudiments of Hydrostatics) of 1585, both of which written in Dutch, Stevin lays the foundations for modern statics. Stevin rejected the Aristotelian tradition of mechanics even in that form supported by Jordanus of Nemore and his pupils, for this form, too, measures forces through the speeds or movement caused by these forces. Because there are no such movements in equilibrium – the static case – Stevin goes back directly to Archimedes, further developing his considerations on the theory of the level. In this Stevin, in part using his famous theorem based on the clootcrans (“wreath of spheres”), succeeds in expressing the condition of equilibrium of weights on an inclined plane, basing the mental experiment upon which it is based on the impossibility of a perpetuum mobile. He also successfully reduces and combines powers, and comes up with a method to determine the centre of gravity in the general case. In his book on hydrostatics, the first systematic portrayal of hydrostatics since Archimedes, in Proposition X he formulates the “hydrostatic paradox”, according to which the pressure on the base of a vessel filled with liquid depends not on the volume of the liquid, but only on the liquid column extending from the base to the surface and its specific gravity, which Stevin also proves experimentally in the practical part of his book. He was also able to explain correctly the equilibrium of water in communicating pipes. Stevin’s main astronomic work is the book De Hemelloop, published in 1608. In this book Stevin describes the Copernican system many years before Galileo, supporting it without reservation, and designates the Copernican thesis as “the true theory”, while also acknowledging and describing the Ptolemaic system in detail. Many of Stevin’s tracts originated from his tasks in the army of the Netherlands, such as De Sterctenbouwing of 1594 and Castrametatio of 1617, which deal primarily with the construction of fortifications and include the principles according to which Moritz of Oranien proceeded in besieging and defending cities. In addition to books about geography and nautical science, Stevin also wrote Het Burgherlick Leven, a book about the life of the bourgeoisie and its legal order. In this book he especially pursues the question of how historically evolved law can be justified. One of his most important juridical principles is that a citizen must always obey the laws and subordinate himself to them, even if the citizen holds the law to be wrong and feels it to be unjust. He believes religion to be imperative for the moral education of children. However, he recognizes that it is not necessary for all citizens to adhere to the same religion. In the final years of his life Stevin increasingly devoted himself to mathematics, summarizing his mathematical and mechanical tracts, including the two books of 1586, in two large folio volumes entitled Wisconstighe Ghedachtenissen from 1605 through 1608. This edition was translated into Latin and French in 1608.
