Was a monk in the order of Saint Augustin in Portugal before settling in England (c. 1764).
Acquainted and maintained an active correspondence with a large number of scholarly friends and scientists, such as Jean-Baptiste Le Roy, Achille-Guillaume Lebègue de Presle, and Franklin.
Lebègue de Presle’s informant about the controversy which had occurred in The Royal Society concerning lightning rods.
Became a correspondent of the Académie royale des sciences at Paris (1771) and a member of The Royal Society of London (1774). Also corresponded with the academies of science at Madrid and St. Petersburg. Authored various works on barometers and other scientific instruments.
Born in Lisbon. Alternate form of the name: Magalhaens.