Phillipe Buache (1700 - 1773) was a late 18th century French cartographer and map publisher. Buache began his cartographic career as the workshop assistant and apprentice to the important and prolific cartographer Guillaume de L'Isle. Upon De L'Isle's untimely death, Buache took over the publishing firm cementing the relationship by marrying De L'Isle's daughter. Over the years, Bauche republished many of De L'Isle's maps and charts. Buache was eventually appointed Premier Geographe du Roi, a position created-for and previously held by Guillaume de L'Isle. Buache is most respected for his introduction of hachuring as a method from displaying underwater elevation on a two dimensional map surface. Buache compiled maps based upon geographic knowledge, scholarly research, the journals of contemporary explorers and missionaries, and direct astronomical observation. Nevertheless, even in 18th century Paris geographical knowledge was severely limited - especially regarding those unexplored portions of the world, including the poles, the Pacific northwest of America, and the interior of Africa and South America. In these areas the Buache, like his primary rival Robert de Vaugondy, must be considered a speculative geographer or 'positive geographer'. Speculative geography was a genre of mapmaking that evolved in Europe, particularly Paris, in the middle to late 18th century. Cartographers in this genre would fill in unknown areas on their maps with speculations based upon their vast knowledge of cartography, personal geographical theories, and often dubious primary source material gathered by explorers and navigators. This approach, which attempted to use the known to validate the unknown, naturally engendered many rivalries. Buache's feuds with other cartographers, most specifically Didier Robert De Vaugondy, resulted in numerous conflicting papers being presented before the Academie des Sciences, of which both were members. The era of speculatively cartography effectively ended with the late 18th century explorations of Captain Cook, Jean Francois de Galaup de La Perouse, and George Vancouver. Buache was succeeded by his nephew Jean-Nicholas Buache de Neuville.