Guillaume Delisle (February 28, 1675 - January 25, 1726) was a French cartographer, born in Paris, France (he also died there).
His father, Claude Delisle (1644-1720) studied law and then later settled in Paris as private teacher in geography and history, and afterwards filled the office of royal censor. He was also a cartographer.
Guillaume Delisle's first works were "The Map of the World" and "The Map of the Continents", both published in 1700. These and the terrestrial maps produced subsequently, which surpassed all similar publications, established the son's fame. In 1702 he became élève, in 1716 adjoint, and in 1718 associé of the Académie des Sciences; and, as the young king's instructor in geography, received the title of First Royal Geographer with a fixed salary, an office which was then created for the first time.
Guillaume Delisle adopted entirely new principles in cartography and set about making a thorough reform in that subject. The map-publishers of the time did not know how to utilize the material supplied mainly by the French astronomers of the latter half of the seventeenth century, and Delisle recognized that the new methods of measuring by scale and of marking the places were very valuable for cartography; with this help he therefore produced a new and more accurate picture of the world.
When his astronomical information fell short he carefully examined and sifted all the books of travel and all the maps he could find, and the products of this reading were dovetailed neatly into the facts which he had already at hand. According to a fixed method he worked up the several continents and countries one by one, France in particular. In disputed points he named his source on the map or wrote additional notes, the majority of which were published in the writings of the Academy. One particular recommendation of his charts is that he employed a fixed scale of measurement for regions closely connected with one another. No less famous than his astronomical corrections are the completeness of his topography and the care displayed in the orthography of the names.