A family from Basle that produced a stream of significant mathematicians, some of them very important indeed. The best known are the brothers Jacques (or James or Jakob) and Jean (or John or Johann), and Jean's son Daniel. JacquesBernoulli (1654–1705) did much work on the newly developed calculus, but is chiefly remembered for his contributions to probability theory: the Ars conjectandi was published, after his death, in 1713. The work of JeanBernoulli (1667–1748) was more definitely within calculus: he discovered l'Hôpital's rule (see under H) and proposed the brachistochrone problem. He was one of the founders of the calculus of variations. In the next generation, DanielBernoulli (1700–82) was the member of the family whose mathematical work was mainly in hydrodynamics.