Willem Jacob 's Gravesande

Willem Jacob ‘s Gravesande (26 September 1688 – 28 February 1742) was a Dutch mathematician and natural philosopher, chiefly remembered for developing experimental demonstrations of the laws of classical mechanics. As professor of mathematics, astronomy, and philosophy at Leiden University, he helped to propagate Isaac Newton‘s ideas in Continental Europe.

Life

Born in ‘s-Hertogenbosch, ‘s Gravesande studied law at Leiden University, where he defended a thesis on suicide and earned a doctorate in 1707. He then practised law in The Hague while also participating in intellectual discussions and cultivating his interest in the mathematical sciences. His Essai de perspective (“Essay on Perspective”), published in 1711, was praised by the influential Swiss mathematician Johann Bernoulli.[1] In The Hague, ‘s Gravesande also helped to establish the Journal littéraire (“Literary journal”), a learned periodical first published in 1713.[2]

In 1715, ‘s Gravesande visited London as part of a Dutch delegation sent to welcome the Hanoverian succession in Great Britain.[2] In London, ‘s Gravesande met both King George I and Isaac Newton, and was elected a Fellow of the Royal Society.[3] In 1717 he became professor of mathematics and astronomy in Leiden. From that position, he was instrumental in introducing Newton’s work to the Netherlands. He also obtained the chairs of civil and military architecture in 1730 and philosophy in 1734.[2] As a philosopher, he opposed fatalists like Hobbes and Spinoza.

‘s Gravesande was married to Anna Sacrelaire in 1720. They had two sons, both of whom died in adolescence. In 1724, Peter the Great offered ‘s Gravesande a position in the new Imperial Saint Petersburg Academy of Sciences. In 1737 he received an offer from Frederick the Great to join the Prussian Academy of Sciences in Berlin. He declined both offers, opting to remain in Leiden.[2]

's Gravesande's ring

‘s Gravesande is also remembered for his invention of a simple experiment demonstrating thermal expansion, which has been used in physics education since.

This is known today as “‘s Gravesande’s experiment” or “‘s Gravesande’s ring”. The apparatus consists of a small metal ball on a chain or handle, and a metal ring on a stand. The ring is just big enough so that when the ring and ball are at the same temperature, the ball fits through the ring.

 However, if the ball is heated by dipping it into boiling water or playing the flame of a spirit lamp over it, the metal will expand, and the ball will no longer fit through the ring. When the ball has cooled down, it will fit through the ring again.