[120] This work appears to have established his reputation. In the year 1702 he became a member of the Academy, not as a geographer--this department was not established until the year 1730--but as an astronomer under Cassini. Sandler, loc. cit.; Vivien de Saint-Martin, M. Histoire de la géographie. Paris, 1875. p. 423. This last-named author says: “La Mappemonde de Guillaume Delisle et ses cartes particulières des quarte partiée du monde, publiées en 1700, remenèrent enfin pour la première fois à leurs véritables places et à leurs dimensions réelles les parties orientales de l’ancien continent. Quelle que fussent les améliorations de détail que dût recevoir par la suit la carte du monde,--et ces améliorations etaient immens,--l’honneur d’en avoir apéré la réforme radical suffit pour éterniser le nom Guillaume Delisle.” [121] Sandler, op. cit. This was an error having its origin in Ptolemy’s geography, as set down in the Ptolemy maps. The two most significant errors in the Ptolemaic cartography were (a) the representation of the Indian Ocean as an enclosed sea; (b) the too great extension in longitude given to the Mediterranean Sea. A correction of the first of these errors followed quickly after the discovery of the sea route to the Indies of the East. As a result incident to the second error the Asiatic regions were extended much too far eastward, the maps as late as the seventeenth century showing the coast of China to lie at least twenty-five degrees too far in that direction. The invention of the telescope in the first decade of the seventeenth century and of the pendulum clock about the middle of the century made possible a more accurate determination of the location of places, and an improvement in map construction soon followed. See also Wolf, Geschichte, pp. 355-362; 369-373. [122] Wolf, op. cit., pp. 400-403. This came to be but one of the many methods employed in the effort to determine longitude. One of the most interesting and most recent is that in which wireless telegraphy has been called into service. See Hoogewerff, Capt. J.A. Washington-Paris Longitude by radio signals by F.B. Littell and G.A. Hill. (In: Astronomical Journal. Albany, 1915.) [123] See “Nolin” and “Delisle.” (In: Mémoire pour l’histoire des sciences et des beaux arts. Trévoux, 1702. p. 166.); “Nolin.” (In: Nouvelle biographie.); Lelewel. Géographie du moyen âge, II. p. 202; Sandler, op. cit., p. 15. [124] Sandler, op. cit., reproduces Delisle’s world map of 1700, pl. iv. [125] Wolf, op. cit., pp. 449-452; Mémoires pour servir a l’histoire des sciences et a celle de l’observatoire royal de Paris. Paris, 1810. pp. 255-309; “Cassini, Jean-Dominique.” (In: Nouvelle biographie.) In this last article may be found a long list of Cassini’s publications.