Simon Stevin

Portrait of Simon Stevin

Whose Wreath Of Balls Would Not Move · Engineer & Mathematician · 1548–1620

The engineer who settled how forces combine by hanging a loop of fourteen balls over a sloping prism and pointing out that if it moved at all it would move for ever — and who gave Europe the decimal fraction in a pamphlet of twenty-nine pages.

Who was Stevin?

Simon Stevin was born at Bruges in 1548, worked as a bookkeeper and a cashier, and moved north to the Dutch Republic, where he took a degree at Leiden at thirty-five and entered the service of Prince Maurice of Nassau as engineer and eventually quartermaster-general of the army. His mechanics is contained in De Beghinselen der Weeghconst of 1586 — the principles of the art of weighing — and its central proof is the one he wanted on his tombstone. Take a triangular prism standing on a level base, with two sloping faces of different steepness. Over it drape a closed loop of string carrying fourteen equally spaced identical balls. The loop cannot start to move of its own accord, because after any movement the arrangement would look exactly as it did before, so it would have to keep moving for ever, which is absurd. The loop therefore hangs at rest; and since the balls dangling below the prism balance each other by symmetry, the balls on the two slopes must balance too — four on the gentle slope against two on the steep, in the ratio of the lengths of the faces. From this Stevin derived how forces acting in different directions combine, by completing the figure now called the parallelogram of forces. In the same period he and Jan Cornets de Groot dropped two lead spheres of very different weights from a tower in Delft and reported that they struck the ground together, some three years before Galileo's work on falling bodies. He also published De Thiende in 1585, which introduced decimal fractions to a European readership, designed the drainage and sluice systems that made Dutch land, wrote on fortification and double-entry bookkeeping, and built a sailing chariot that carried twenty-eight passengers along the beach at Scheveningen faster than horses could run.

Major achievements

Life in brief

Explore the life of Stevin — five chapters

  1. The Bookkeeper Who Went to University at Thirty-Five — Bruges, Antwerp, and the new Republic
  2. The Wreath of Balls — A proof that runs on the impossibility of perpetual motion
  3. Two Lead Weights From a Tower in Delft — An experiment reported in a paragraph
  4. Twenty-Nine Pages That Changed European Arithmetic — De Thiende, and the hydrostatic paradox
  5. Sluices, Fortifications and a Chariot That Beat Horses — Engineering for a country that had to be built

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