Johann Bernoulli (1667-1748)

Johann Bernoulli is one of several noteworthy mathematicians from the same family. He was influenced tremendously by his brother Jacob, who was twelve years older than Johann was. He originally toyed with the idea of going into medicine, writing a dissertation on fermentation and effervescence. It is not known how he decided to focus on mathematics rather than medicine, but he was probably influenced by his brother's math successes. Johann's early significant work was in the expansion of differential calculus topics. In fact, Johann developed what is now known as l'Hopital's rule, used to determine the value of the limit of what is called an indeterminate form. L'Hopital had published a book on differential calculus that apparently simply rewrote a set of lecture notes that Bernoulli had developed. When Bernoulli protested that his work had been plagiarized, l'Hopital offered Bernoulli a significant cash payment, on the condition that Johann would not publicize the information. Bernoulli's sons, mathematicians in their own right, knew of this arrangement, and spoke of it often after the death of their father. Many dismissed their claims, but in the 1920's a copy of Johann's original notes were discovered, containing the rule now attributed to l'Hopital. The notes preceded the publishing of l'Hopital's book by two years, and the Bernoulli family's claims were vindicated. Bernoulli also worked in applied physics and mechanics. His tombstone bears the inscription "The Archimedes of His Age".