"Will the cannon ball come back down again?" This old woodcut, taken from the correspondence of Rene Descartes, illustrates an experiment proposed by Father Mersenne, contemporary and friend of Galileo, to test the behavior of falling bodies. The French caption reads "Retombera-t-il?" which means, "Will it fall again?" Marin Mersenne, Marin Mersennus or le P癡re Mersenne (September 8, 1588 - September 1, 1648) was a French theologian, philosopher, mathematician and music theorist, often referred to as the "father of acoustics". Mersenne, an ordained priest, had many contacts in the scientific world and has been called "the center of the world of science and mathematics during the first half of the 1600s".