Simeon Poisson developed many novel applications of mathematics for statistics and physics. He was born at Pithviers on June 21, 1781, and died at Paris on April 25, 1840. His father had been a private soldier, and on his retirement was given a small administrative post in his native village. When the French revolution broke out, his father assumed the government of the village, and soon became a local dignitary.

When Simeon was a small boy, he was left in the care of a nursemaid. Sometimes the nursemaid would go out and leave him suspended by a small cord attached to a nail fixed in the wall, a precaution to prevent him from perishing under the teeth of the various animals and animalculae that roamed the floor. To entertain himself, Simeon would swing from one side to the other. He attributed this to his interest in pendulums that occupied much of his later work.

He was educated by his father who prodded him to be a doctor. His uncle offered to teach him medicine, and began by making him prick the veins of cabbage-leaves with a lancet. When he had perfected this, he was allowed to practice on humans, but in the first case that he did this by himself, the patient died within a few hours. Although the other physicians assured him that this was not an uncommon occurance, he vowed he would have nothing more to do with the medical profession.

Upon returning home, he discovered a copy of a question set from the Polytechnic school among the official papers sent to his father. This chance event determined his career. At the age of seventeen he entered the Polytechic. A memoir on finite differences which he wrote when only eighteen was so impressive that it was rapidly published in a prestigious journal. As soon as he had finished his studies he was appointed as a lecturer. Throughout his life he held various scientific posts and professorships. He made the study of mathematics his hobby as well as his business.

Over his life Simeon Poisson wrote between 300-400 manuscripts and books on a variety of mathematical topics, including pure mathematics, the application of mathematics to physical problems, the probability of random events, the theory of electrostatics and magnetism (which led the forefront of the new field of quantum mechanics), physical astronomy, and wave theory.

One of Simeon Poisson's contributions was the development of equations to analyze random events, later dubbed the Poisson Distribution. The fame of this distribution is often attributed to the following story. Many soldiers in the Prussian Army died due to kicks from horses. To determine whether this was due to a random occurance or the wrath of god, the Czar commissioned the Russian mathematician Ladislaus Bortkiewicz to determine the statistical significance of the events. Fourteen corps were examined, each for twenty years. For over half the corps-year combinations there were no deaths from horse kicks; for the other combinations the number of deaths ranged up to four. Presumably the risk of lethal horse kicks varied over years and corps, yet the over-all distribution fit remarkably well to a Poisson distribution.

**SOURCES:**

Wilkins, D. A collection of mathematical biographies: www.maths.tcd.ie/pub/HistMath/People/Poisson/RouseBall/RB_Poisson.html

O'Connor, J., and E. Robertson. Ladislaus Josephowitsch Bortkiewicz: www-groups.dcs.st-andrews.ac.uk/~history/Mathematicians/Bortkiewicz.html