PETER OF MARICOURT (13th century), a French savant, to whom his disciple, Roger Bacon, pays the highest tribute in his opus tertium and other works. According to Bacon he was a recluse who devoted himself to the study of nature, was able to work metals, invented armour and assisted St Louis in one of his expeditions more than his whole army. According to Emile Charles ( Roger Bacon sa vie, ses ouvrages, ses doctrines, 1861), Peter of Maricourt is the Pierre Peregrin (or Pelerin) de Maricourt (Meharicourt in Picardy), known also as Petrus Peregrinus of Picardy, one of whose letters, De magnete, is partly reproduced in Libri's Hist. des sciences mathematiques en Italie (1838), ii. 70-71, 487-505.