Esprit Pézenas

Esprit Pézenas was a French Jesuit astronomer, hydrographer and mathematician, born in Avignon on 28 November 1692 and dead there on 4 February 1776, who worked at the observatory in Marseilles. He studied at the Jesuit college, taught physics, logic and metaphysics at Lyons and Aix, and in 1728 became professor of hydrography at Marseilles, teaching navy officers navigation. He wrote on hydrography, the measurement of tonnage and the differential calculus, and in 1749 became director of the Observatoire Sainte-Croix. In 1767 he translated the work of John Harrison on the chronometer for use in finding longitude. He claimed that Pierre Vernier deserved credit for the Vernier scale rather than Pedro Nunes, is credited with the 1731 discovery of the gegenschein, and from sunspots computed a solar rotation period of 26 days and 9 hours. He retired to Avignon in 1763.