Minor Scientific Writers

Abstract

Octoul’s name occurs in the long list which Hilarion de Coste gives of Mersenne’s correspondents.¹He was an active member of the Order and reached some prominence in the administration of the Province of Provence since he signed the “approbatio”for André Réal’s admirably clear introduction to the study of Hebrew²His name is to be found in biographical dictionaries of the Midi³and in François de Lalande’s Bibliographie astronomique.⁴ He was the author of a single printed work, Inventa astronomica… terrae meridianis per observationem cum pyramidis astronomica comparandis…(Avignon, 1643), a strange mixture of astrology and highly practical details of aids to navigation. It is possible that Octoul was amongst those friends to whom Mersenne refers in the Cogitata; they urged him to publish hisArs navigandias a part of this work rather than in theUniversae geomatriae synopsis.⁵ It is at least apposite to note that the Ars navigandi bears a separate “épître dédicatoire” to the Bishop of Marseilles where Octoul was known. His book contained information that Mersenne would have found of interest; “11 propose,” says Lalande, “un instrument pour prendre la hauteur (du soleil); c’est un secteur à pinnules⁶ dont il faisait tourner le limbe dans une coulisse circulaire concentrique placée dans le plan du méridien.”