142 MAPS AND THEIR MAKERS 



which the epoch-making work of Newton exerted through 

 astronomy and geodesy upon the development of cartography. 

 Nevertheless, by and large, British map-making until the late 

 eighteenth century was definitely behind that of other nations. 

 Perhaps the best of a poor field in the first decades was Herman 

 Moll, a Dutchman who came to London some time before 1682. 

 His numerous maps are rather poorly designed and crudely 

 engraved, but he made some effort to keep abreast of conti- 

 nental advances. 



In 1738, John Green was lamenting the poor state into 

 which the science had lapsed: he pointed out that cartography 

 had fallen entirely into the hands of engravers, who copied 

 each other without discrimination. Those "ignorant or mer- 

 cenary Hands" who happened to become possessed of original 

 material jealously concealed it from their rivals. To such 

 conduct he attributed "the little Esteem, or rather great 

 Contempt, that Maps are in here". He himself made some 

 effort to remedy this state of affairs, in part as an employee of 

 Thomas Jeffreys, but the first important British contribution 

 was made through the development of instrumental equipment, 

 which was effective in improving first the hydrographic charts, 

 and then the maps. 



In the eighteenth century the fundamental advances in 

 mathematics and astronomy initiated by Sir Isaac Newton 

 gradually bore fruit. The motions of the heavenly bodies were 

 marked out, so that they could be accurately predicted for long 

 periods, and eventually published annually in the 'Nautical 

 Almanac' from about 1767. With the aid of lunar tables, the 

 method of determining longitude within one degree by lunar 

 distances was perfected. To this accuracy, the advances in 

 the design of instruments also contributed; John Hadley had 

 improved the quadrant by the introduction of reflecting 

 mirrors^, and more accurate readings were obtained from the 

 use of the vernier scale. Meanwhile, John Harrison was engaged 

 in designing and constructing a time piece which would be 

 sufficiently robust and accurate to allow longitude to be 

 determined from the difference between local time and the 

 time indicated by the chronometer for a given meridian. 



^The method had earlier been described by Sir Isaac Newton. 



