"It was sufficiently clear," say the Memoirs of the Academy of Sciences, that the maps unduly extended the Continents of Europe, Africa, and America, and narrowed the Pacific Ocean between Asia and Europe. These errors had caused singular mistakes. During M. de Chaumont's voyage, when he went as Louis XIV.'s ambassador to Siam, the pilots, trusting to their charts, were mistaken in their calculations, and both in going and in returning went a good deal further than they imagined. In proceeding from the Cape of Good Hope to the island of Java they imagined themselves a long way from the Strait of Sunda, when in reality they were more than sixty leagues beyond it. And they were forced to put back for two days with a favourable wind to enter it. In the same way upon their return voyage from the Cape of Good Hope to France, they found themselves at the island of Flores, the most western of the Azores, when they conceived themselves to be at least a hundred and fifty leagues eastward of it. They were obliged to navigate for twelve days in an easterly direction in order to reach the French coast. As we have already said, the corrections made in the map of France were considerable. It was recognized that Perpignan and Collioures more especially were far more to the east than had been supposed. To gain a fair idea of the alteration, one has only to glance at the map of France published in the first part of the seventh volume of the memoirs of the Academy of Sciences. All the astronomical observations to which we have called attention are noted in it, and the original outline of the map, published by Sanson in 1679, makes the modification apparent. [Illustration: Map of France, corrected by order of the king, in accordance with the instructions of the Members of the Academy of Sciences. (Fac-simile of early engraving.)] Cassini was right in saying that cartography was no longer at its height as a science. In reality, Sanson had blindly followed the longitudes of Ptolemy, without taking any note of astronomical observations. His sons and grandsons had simply re-edited his maps as they were completed, and other geographers followed the same course. William Delisle was the first to construct new maps, and to make use of modern discoveries. He arbitrarily rejected all that had been done before his time. His enthusiasm was so great that he had entirely carried out his project at the age of twenty-five. His brother, Joseph Nicolas, who taught astronomy in Russia, sent William materials for his maps. At the same time his younger brother, Delisle de la Ceyere, visited the coast of the Arctic Ocean, and astronomically fixed the position of the most important points. He embarked on board De Behring's vessel and died at Kamtchatka. That was the work of the three Delisles, but to William belongs the glory of having revolutionized geography.