Pierre Varignon

Pierre Varignon (1654 to 1722) was a French mathematician educated at the Jesuit College and the University of Caen, who took Holy Orders in 1683 and became professor of mathematics at the College Mazarin in Paris in 1688, the year he was elected to the Academie Royale des Sciences. He was elected to the Berlin Academy in 1713 and to the Royal Society in 1718. A friend of Isaac Newton, Leibniz and the Bernoulli family, he made his main contributions to graphic statics and mechanics, treating mechanics through the composition of forces in his Projet d'une nouvelle mecanique of 1687. Apart from Guillaume de l'Hopital he was the earliest and strongest French advocate of the infinitesimal calculus, and he adapted Leibniz's calculus to the inertial mechanics of Newton's Principia. In 1704 he invented the U-tube manometer, a device able to measure rarefaction in gases.