A French professor of mathematics noted for his contribution to mathematics. Laplace was the son of a farm labourer who owed his education to some rich neighbours. He solved many problems concerning the motion of the solar system. He also worked on surface tension and, with Antoine Lavoisier (1743–94), did work on the measurement of the heat produced during chemical changes. In 1822 he persuaded the French Academy to carry out experiments to measure the velocity of sound over a distance of eleven miles by firing cannons. The result confirmed his belief that when sound waves pass, the air cools as it expands and heats up as it contracts.