Simon Stevin

Simon Stevin (1548 – 1620) was a Flemish-Dutch engineer and mathematician, who was one the first to write rational numbers as decimal fractions (although he did not yet use the decimal point as place holder). He decomposed forces by using diagrams that were equivalent to what we now call "the parallelogram of forces" (see this article) and he did experiments—eighteen years before Galileo Galilei—that refuted Aristotle's law of free fall, that is, he found that heavy bodies do not fall faster than light ones..

Life

Simon Stevin was born in Bruges, one of the important cities of Flanders, the Dutch speaking part of Belgium. He was a natural child of Antheunis Stevin and Cathelyne van der Poort. He worked as a merchant's bookkeeper in Antwerp, the largest city in Flanders, and moved around 1580 to The Netherlands, first to Middelburg and then in 1581 to Leiden. He was matriculated as a student in the University of Leiden on February 16th, 1583. Simon Stevin had four children. As to his marriage we only know of a notice of marriage with Catherina Cray at Leyden on April 10th 1616, when he was 68 years old (but Simon Stevin had children already before 1616). Stevin died in 1620; the exact date nor the place is known but he passed away between February 20th and April 8th and most probably in the Hague.

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Work

While still in Antwerp, Stevin composed world's first table of interests Tafelen van Interest (1582).

In 1585 he published a booklet, De Thiende [The Tenth], in which he presented an elementary account of decimal fractions and their daily use. His booklet starts with:

Den Sterrekyckers, Landt meters, Tapijtmeters, Wijnmeters, Lichaemmeters int ghemeene, Muntmeesters, ende allen Cooplieden, wenscht Simon Stevin Gheluck.

making clear that he had very practical applications in mind with his new arithmetic tools. Although he did not invent decimal fractions and his notation was rather unwieldy, he established their use in day-to-day mathematics.

In 1586 he published De beghinselen der weeghconst [The principles of the art of weighing]. By weeghconst Stevin means the part of mechanics called statics. This field was founded by Archimedes and Stevin continued his theoretical work on the forces that keep solid bodies in their place. Stevin treats a solid body on a sloping plane and decomposes the gravitational force in a component perpendicular to the plane and one that keeps the body in rest on the slope; doing this he introduced the "the parallelogram of forces". In the same year Stevin published a report on his experiment, performed in Delft together with the father of Hugo Grotius, in which two lead spheres, one 10 times as heavy as the other, were dropped from a church tower. After falling a distance of 30 feet, the balls landed on a wooden plank. The two observers heard one bang only and concluded that the two balls fell with equal speed.

Around 1590 Stevin became consultant for Maurice, Prince of Orange, who had succeeded his father William the Silent as leader of the Dutch Revolt. Stevin instructed Maurice in various subjects (see Wisconstighe Ghedachtenissen 1605-1608) and constructed his famous sailing-car for him. In 1600 Stevin was asked to compose an instruction for a school of engineers, part of Leiden university.

Stevin loved the Dutch language and was a purist. He invented many words that are still current in Dutch (a famous example is wiskunde—literally the art of certainties—for mathematics). After 1582 he refused to write in any other language than Dutch, which gave him a lower international profile than a man of his talents deserved.

Reference

E. J. Dijksterhuis, Simon Stevin, Martinus Nijhoff, The Hague (1943) (In Dutch)