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 and the first experimental measurement of kinetic energy. 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. In The Hague, 's Gravesande also helped to establish the Journal littéraire ("Literary journal"), a learned periodical first published in 1713. In 1715, 's Gravesande visited London as part of a Dutch delegation sent to welcome the Hanoverian succession in Great Britain. In London, 's Gravesande met both King George I and Isaac Newton, and was elected a Fellow of the Royal Society. 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. 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. Mechanics Gravesande's main scientific work is Physices elementa mathematica, experimentis confirmata, sive introductio ad philosophiam Newtonianam ("Mathematical Elements of Natural Philosophy, Confirmed by Experiments; or, an Introduction to Newtonian Philosophy"), published in Leiden in 1720. In that book, he laid the foundations for the teaching of Newtonian mechanics through experimental demonstrations. He presented his work before audiences that included Voltaire, Albrecht von Haller, and Émilie du Châtelet (the translator of Newton's Principia whose later commentary incorporated 's Gravesande's 1722 experimental discovery of kinetic energy). 's Gravesande's book was soon translated into English by John Theophilus Desaguliers, curator of experiments