Cruquius adopted this method of showing relief on a chart of the Merwede in 1728; P. Buache similarly showed the depths of the English Channel in 1737; J. G. Lehmann used contours as the proper scientific basis of hachuring in 1783, and a contoured map of France was produced in 1791 by Dupain-Triel. The atlas of Germany, begun by a famous cartographer of Nuremberg, Homann, and published in 1753, illustrates successive stages in the evolution of hill-shading; for the earliest map in the series, dating from thirty-five years earlier, shows the first endeavour to differentiate the shading according to the steepness of slope. In the meantime the use of maps had already been recognized in some of the many special departments of geographical science from which they are now inseparable. For example, the variation of the compass had been mapped by C. Burrus early in the seventeenth century, and was more effectively worked out by the famous astronomer E. Halley in 1683. A. Kircher, again, took an early step in the department of oceanography by mapping currents and other features of the oceans in 1665. [Illustration: Fig. 17.--The World according to Mercator (1587).] From what has been written above, it may be inferred, and justly so, that Holland and France led the way in the development of cartography from the sixteenth to the eighteenth century. But by the end of the sixteenth century and throughout the seventeenth the mapping of most of the western European countries was rapidly extended, as in Germany, Austria, Switzerland, and Italy, in Denmark and Scandinavia, and in the British Isles. German local mapping ranked high, as appears from the collection in Ortelius’s Theatrum Orbis (1570) and from Mercator’s map of Germany (1585), both of which show the superiority of the cartographical material available for Germany. A large number of maps were based on original survey work. As early as 1566 a map of Bavaria by Philip Bienewitz, on a scale approximating (in terms of our survey) to two and a quarter miles to an inch, gave the results of a regular survey of remarkable accuracy for the period. Such was also the case (to select an example at home) with Christopher Saxton’s atlas of England and Wales (1574–79), in which the maps are about an inch to three miles in scale. This work marked the beginning of an important period in the history of British maps; Timothy Pont’s maps of Scotland appeared about 1608, and John Speed’s, of the British Isles on about the same scale as Saxton’s, in 1610. Hollar adopted a smaller scale (about five miles to the inch) in his maps of England and Wales dated 1644. These were of service in the Civil War, and the importance of military requirements in furthering the extension of organized survey work--which will appear in its subsequent history--is early exemplified in a survey of Ireland made under an Act of 1653; though this, the first British cadastral survey, was not a preliminary but a result of