Simeon Poisson

Simeon-Denis Poisson , French mathematician, well known for definite integrals, electromagnetic theory, and probability.  Poisson’s family had intended him for a medical career, but he showed little enthusiasm.  In about 1798 Simeon began studying mathematics in Paris.

Simeon wasn’t the first child but several of his older brothers and sisters had not survived.  His health was also very weak as a child and he was lucky to pull through.  Simeon’s father had a large influence on him, taking time to teach him to read and write as soon as possible.  Simeon’s father decided that the medical profession would be a safe future for his son.  An uncle of Simeon was a surgeon in Fontainebleau.  Simeon was sent there to become an apprentice surgeon.  Soon to find out Simeon found himself to not be strong stomached and not too good with coordination.

Few people are able to achieve academic success as quickly as Poisson did.  He began to study mathematics in 1798 at Paris.  His only weakness was the lack of coordination which had made a career as a surgeon impossible.  This was still a drawback to him in some parts for when drawing mathematical diagrams was quite beyond his capability.  His teachers Laplace and Lagrange quickly saw his mathematical talents.  In his final year of study he wrote a paper on the theory of equations and Bézout's theorem.  The rest of his career, until his death on the 25th of April 1840, was almost entirely occupied in the composition and publication of his many works, and the duties of his many educational offices to which he was successively appointed. Immediately after finishing his course at the École Polytechnique he was appointed repetiteur there. He was made professeur suppléant in 1802, and full professor in succession to Jean Baptiste Joseph Fourier in 1806.  In 1808 he became astronomer to the Bureau des Longitudes; and when the Faculté des Sciences was opened in 1809 he was appointed professeur de la mécanique rationelle.  He further became member of the Institute in 1812, examiner at the military school at St. Cyr in 1815, leaving examiner at the École Polytechnique in 1816, councilor of the university in 1820, and geometer to the Bureau des Longitudes in succession to Laplace in 1827.  This was said to have such quality that he was allowed to graduate in 1800 without taking the final exam.  Simeon’s most famous work included the application of mathematics to electricity, magnetism, mechanics, and other areas of physics.  Perhaps the most memorable of his work applied in mathematics are those on the theory of electrostatics and magnetism.  The most important of those on physical astronomy are the two read in 1806 on the secular inequalities of the average motions of the planets.  In these, Poisson discusses the question of the stability of the planetary orbits, and shows that the result can be extended to the third order of small quantities: these were the memoirs which led to Lagrange's famous memoir of 1808.  Poisson also published a paper in 1821 on the liberation of the moon; and another in 1827 on the motion of the earth about its center of gravity.  His most important memoirs on the theory of attraction are one in 1829 on the attraction of spheroids, and another in 1835 on the attraction of a homogeneous ellipsoid, and his memoir in 1825 on the theory of waves.         

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