Jacques Bernoulli, Swis mathematician, c 1700.
© Science Museum / Science & Society Picture Library
Engraving of Jacques Bernoulli (1654-1705) was the brother of the mathematician Jean Bernoulli (1667-1748) and was profesor of mathematics at Basel. He made important contributions to the understanding of calculus. He investigated infinite series, transcendental curves and the catenary. Bernoulli first used the term 'integral', when applying Gottfried Leibniz's differential calculus to a problem in geometry. His 'Ars conjectandi' (1713) made significant contributions to probablility theory.