Note 121 — Chapter XII · Globes and Globe Makers of the First Half of the Eighteenth Century—from Delisle to Ferguson

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.