Hospital, William-Francis-Antony, Marquis De L'

, a great mathematician of France, was born of a branch of the preceding family, in 1661. He was a geometrician almost from his infancy; for one day being at the duke de Rohan’s, where some able mathematicians were speaking of a problem of PaschaPs, which appeared to them extremely difficult, he ventured to say, that he, believed he could solve it. They were amazed at what appeared such unpardonable presumption in a boy of fifteen, for he was then no more, yet it a few days be sent them the solution. He entered early into the army, but always preserved his love for the mathematics, and studied them even in his tent; whither he used to retire, it is said, not only to study, but also to conceal his application to study: for in | those days, to be knowing in the sciences was thought to derogate from nobility; and a soldier of quality, to preserve his dignity, was in some measure obliged to hide his literary attainments. De l'Hospital was a captain of horse; but, being extremely short-sighted, and exposed on that account to perpetual inconveniences and errors, he at length quitted the army, and applied himself entirely to his favourite amusement. He contracted a friendship with Malbranche, judging by his “Recherche de la Verite*,” that he must be an excellent guide in the sciences; and he took his opinion upon all occasions. His abilities and knowledge were no longer a secret: and at the age of thirty-two he gave a public solution of problems, drawn from the deepest geometry, which had been proposed to mathematicians in the acts of Leipsic. In 1693 he was received an honorary member of the academy of sciences at Paris; and published a work upon sir Isaac Newton’s calculations, entitled “L'Analyse des iniinimens petits.” He was the first in France who wrote on this subject: and on this account was regarded almost as a prodigy. He engaged afterwards in another work of the mathematical kind, in which he included “Les Sectiones coniques, les Lieux georoetriques, la Construction des Equations,” and “Une Theorie des Courbes mechaniques:” but a little before he had finished it, he was seized with a fever, of which he died Feb. 2, 1704, aged 49. It was published after his death, viz. in 1707. There are also six of his pieces inserted in different volumes of the memoirs of the academy of sciences. ¹