Mersenne, Marin

(1588-1648) (Abbé Mersenne)

   philosopher, scholar, cleric

   Born near oizé, Maine, Marin Mersenne, who had a collective view of, and dedicated himself to, science, favored exchanges between the scholars of his time, visiting and carrying on with them an abundant correspondence (rené descartes, blaise pascal, pierre de fermât, Isaac Beekmann, Evan-gelista Torricelli). He published Mécaniques de Galilée, as well as five smaller works on science (1634), and organized the Academia Parisiensis in 1635. Among the first laboratory scholars, he helped to develop quantitative physics. Before the limits of science he developed a pragmatic philosophical position. The study of Galileo's theories concerning gravity led him to undertake experiments to prove those ideas, notably with the help of a pendulum that he used to discover the law of proportionality of the square root of length. He was also the first to use the pendulum to determine the intensity of weight and gravity (1644). Abbé Mersenne also studied the telescope with a parabolic mirror. But his most important works concerned acoustics; he discovered the laws of sonorous tubes and vibrating cords, observed the existence of superior harmonics, and determined the relationship among the frequencies of notes. Finally, he used the phenomenon of the echo to measure the speed of sound (1636).