Ismael Boulliau

Boulliau was ordained in 1630, becoming a vicar in a parish including Loudun. He held this position for about three years when he went to Paris. There he became a librarian working for the keepers of the Royal Library.

In his capacity as librarian he travelled widely in Italy, Holland and Germany buying books. In 1657, after the death of his two employers, he worked as a secretary to the French ambassador to Holland. He was to work again as a librarian, this time to the same French ambassador, but after a dispute with him in 1666 he lived at the Collège de Laon. He spent the last five years of his life in the same occupation in which he started his career, becoming a priest at the Abbey St Victor.

Boulliau was a friend of Pascal, Mersenne and Gassendi and supported Galileo and Copernicus. In 1645 he published Astronomia philolaica which accepts elliptical orbits for planets. He claimed that if a planetary moving force existed then it should vary inversely as the square of the distance (Kepler had claimed the first power). It represents the most significant treatise between Kepler and Newton and it was praised by Newton in his Principia, particularly for the inverse square hypothesis and its accurate tables.

Boulliau was a close associate of Huygens and Huygens turned to him first with his discovery of the rings of Saturn and sent him pendulum clocks.

He was elected a foreign associate of the Royal Society in 1667.

Article by: J J O'Connor and E F Robertson

JOC/EFR December 1996 The URL of this page is:	School_of_Mathematics_and_Statistics University_of_St_Andrews,_Scotland
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