(Lewis Betrand), a learned Jesuit, was born at Montpellier in 1688, and entered among the Jesuits in 1703. He studied polite literature in his youth; and at length applied himself entirely to the study of mathematics and natural philosophy. He distinguished himself by writing on gravity; the ma- thematics; and on the music of colours, a very whimsi- cal idea, which he took great pains to reduce to practice. His piece on gravity, entitled Traité de la Penetraire universelle, was printed at Paris, in 1724. He afterwards published his Mathematique universelle; which occasioned his being unanimously chosen a fel- low of the Royal Society of London, without the least solicitation. He was also a member of the aca- demies of Bordeaux and Rouen; but his Clavecin oculaire made the most noise; and he spent much time and expense in making an harpsichord for the eye, but without success. He also wrote for and ag- ainst Sir Isaac Newton, and published several other works; the principal of which are, Le Plan du Ma- thematique oregé, and a treatise entitled Optique des Couleurs. He led a very exemplary life, and died in 1757.