Sustained cartographic innovations in nascent French Canada: the life and times of Jean Deshayes

Jean Deshayes, a teacher of mathematics in his native France, single-handedly put Québec on the map, literally. An accomplished astronomer, he used the lunar eclipse of 10–11 December 1685 to determine the
settlement’s longitude to unprecedented (although most likely fortuitously high) accuracy for the times. Deshayes contributed invaluable practical insights to the most important contemporary scientific debate—the discussion regarding the shape and size of the Earth—which still resonate today. Over the course of several decades and equipped with an increasingly sophisticated suite of surveyor’s instruments, his careful scientific approach to hydrography and cartography of Canada’s Saint Lawrence River is an excellent example of the zeitgeist associated with the seventeenth century’s ‘Scientific Revolution.’