Ismaël Bullialdus

Ismaël Boulliau (French: [buljo]; Latin: Ismaël Bullialdus; 28 September 1605 – 25 November 1694) was a 17th-century French astronomer, mathematician, and Catholic priest, who was also interested in history, theology, classical studies, and philology. He was an active member of the Republic of Letters, an intellectual community that exchanged ideas. An early defender of the ideas of Nicolaus Copernicus, Johannes Kepler and Galileo Galilei, Ismael Bullialdus has been called "the most noted astronomer of his generation" whose renown is perhaps best exemplified by the claim of 1979 Nobel laureate in Physics Steven Weinberg that in 1640 Bullialdus made "the first suggestion of an inverse-square law." One of his books is Astronomia Philolaica (1645).

Life and career

Ismael Bullialdus was the second-born to his Calvinist parents, Susanna Motet and Ismael Bullialdus. His father was a notary by profession and an amateur astronomer who made observations in Loudun, France. His older brother was originally named after their father Ismael, but died shortly after birth.

At the age of 21, Bullialdus converted to Roman Catholicism and was ordained a priest at age 26. One year later, in 1632, he moved to Paris. Enjoying the patronage of the de Thou family, Bullialdus worked for 30 years in Paris as a librarian associated with the brothers Jacques and Pierre Dupuy, who were working on the Bibliothèque du Roi (Bibliothe), France's first royal library. After the death of his employers, the brothers Dupuy, Bullialdus became secretary to the French ambassador of Holland.