Bernoulli, Daniel
Achievements: Bernoulli’s principle
Born: February 8, 1700; Groningen, Netherlands
Died: March 17, 1782; Basel, Switzerland (Aged 82)
Field & Discipline: Science; Physics; Mathematics; Physicist; Mathematician
Education: University of Heidesberg; University of Strasbourg; University of Basel
Major Work: “Hydrodynamica” (1738)
Life & Times:
Bernoulli was born into a family of wealthy Protestant merchants, a large number of whom became famous mathematicians. Bernoulli’s uncle, Jakob I Bernoulli, was professor of mathematics at Basel and was one of the first to make important advances in the application of the calculus. Bernoulli’s father, [father was] Johann Bernoulli*, who succeeded Jakob at Basel in 1705, was instrumental in spreading the calculus in Europe. Daniel Bernoulli and his brothers were all gifted mathematicians. Daniel learned mathematics from his father and elder brother, from the age of eleven. He resisted his father’s attempts to place him in a merchant’s house and studied medicine before he became fascinated by mathematics.
In 1724, while he was studying medicine in Venice, he published a book entitled “Exercitationes mathematicae”. The book included papers on the mathematics of probability as applied to the game of faro, and on the physics of flowing water. It created such a stir that Bernoulli was invited to the St Petersburg Academy of Sciences in Russia, where he took up a position as professor of mathematics in 1725. In the same year, he won the first of ten prizes from the French Academy of Science, for a paper concerning the most appropriate shape for hourglasses filled with sand or water to be used for measuring time at sea. In Russia Bernoulli worked with the mathematician [a pal of] Euler*, who also became a close friend. While lecturing in medicine, mechanics and physics, Bernoulli investigated the properties of vibrating and rotating bodies, and completed his first important work on oscillations. He also wrote an original thesis on the theory of probability and began his work on hydrodynamics. Bernoulli did not like living in Russia and made several attempts to get a job back in Basel.
In 1732 he was finally appointed to a professorship in anatomy and botany. Among his pupils was Johann Samuel Koenig (the son of [taught son of]Koenig*) who, when dining with Bernoulli, once set him a difficult mathematical problem which Bernoulli solved before the meal ended. While fulfilling his commitments as a lecturer, Bernoulli continued with his research and in 1734 published his completed work on hydrodynamics, in which he used the principle of the conservation of energy to solve the problem of fluid flow. In “Hydrodynamica” Bernoulli considered the equilibrium, pressure, reaction and varied velocities of fluids, both practically and theoretically. Among the problems he considered was a way of propelling boats by the reaction of water ejected from the stern. He presented a formulation of the law of conservation when applied to a fluid. He stated that the energies involved in the conservation principle of a stationary mass remain the same for a non-turbulent, non-viscous flow. The three main energies involved are the gravitational potential energy, the potential energy from the downward force of any fluid above it, and - in a moving flow - the kinetic energy. In what became known as “Bernoulli’s principle” he stated that the pressure in a fluid decreases as its velocity increases. His book superseded the earlier work on hydrodynamics done by the French physicist [superceded work by] Marriotte* and influenced later investigations such as those of [influenced] Osborne Reynolds* on the flow of water through pipes and channels. Fluid mechanics were of great interest to scientists, and Bernoulli’s theory was later challenged by an alternative theory from the French mathematician [theory disputed by] d’Alembert*.
Bernoulli also attempted to solve the kinetic theory of gases. He stated that the gas pressure on the walls of a container could be explained by the rapid advance and retreat motion of a large number of small molecules. Bernoulli’s investigations covered a wide range of subjects, and between 1725 and 1749 he won prizes from the French Academy of Sciences for papers on astronomy, magnetism, gravity, tides, ocean currents, and the motion of ships at sea. In 1735 he shared with his father the prize for a paper on the physical cause of the inclination of the planetary orbits. It is alleged that his father was so annoyed at sharing the prize he threw his son out. Bernoulli shared his third prize (on the subject of tides) with Euler.
Bernoulli finally took the chair of physics at Basel in 1750, and remained in that position for over twenty-five years. He gave very popular lectures, with demonstrations of innovative experiments in physics, and his pupils included [taught] Des Barres*. Bernoulli’s work on differential equations inspired the French physicist [inspired] Andre-Marie Ampere*. He and Euler co-operated on research into on oscillations in rigid bodies and the mechanics of flexible and elastic bodies. In his latter years, Bernoulli concentrated most on applying theories of probability, mainly to useful purposes such as inoculation, the duration of married life in the two sexes, and the relative proportion of male and female births.
Extra Connections: He knew [knew] Venturi*
Assessment: Bernoulli contributed valuable research to many problems in applied mathematics, particularly in the fields of probability, differential equations and the calculus.
Oneliner: Daniel Bernoulli, major mathematician
Language: German
Father: Johann Bernoulli
Mother: Dorothea Falkner
Spouse: None
Children: None
Bibliography:
- Bell, E.T., Men of Mathematics,Penguin Books, Harmondsworth, Middlesex, England, 1965.