146 MAPS AND THEIR MAKERS 



extensive area to fall under the Company's complete control. 

 In his twelve years in India (from 1767 to 1777 he was the 

 first Surveyor- General of Bengal) Rennell initiated and 

 directed a comprehensive and uniform survey of Bengal and 

 Bihar, to meet military, administrative and commercial 

 demands. The survey was based upon a network of distance 

 and bearing traverses, controlled as the work progressed by 

 cross bearings and closed circuits. A further control was 

 afforded by observations for latitudes. Distances on large-scale 

 work were measured by chaining, in other cases by perambu- 

 lator. Quadrants were employed for horizontal angular measure- 

 ments as well as for obtaining latitudes, and theodolites were 

 gradually introduced. Much of the work was based on traverses 

 along the rivers and main roads, details of the countryside 

 being largely filled in by estimation. Given the methods 

 employed and the difficulties encountered — Rennell himself 

 was severely wounded and suflFered constant attacks of fever — 

 the results were extremely creditable, and the standard of 

 mapping was much higher than that of many European 

 countries. 



The first edition of the 'Bengal Atlas' ,with maps on a scale 

 of 5 miles to 1 inch, was published in London in 1779, two 

 years after Rennell's return on pension. In London, he con- 

 tinued to maintain his interest in the mapping of India, and 

 in 1782 published his great 'Map of Hindoustan' with a 

 'Memoir'. This map, in four sheets on the scale of one equa- 

 torial degree to one inch, was a remarkable piece of compila- 

 tion. The sources used are critically discussed in the 'Memoir' ; 

 they included the East India Company charts communicated 

 by Dalrymple and route surveys by military engineers accom- 

 panying military expeditions, adjusted to an astronomical 

 framework of latitudes and longitudes, the latter mainly for 

 coastal cities obtained from the eclipses of Jupiter's satellites. 

 For the Punjab he relied largely upon a map done by a native, 

 giving the courses and names of the five rivers, "which we have 

 never had before". With the advance of British arms, Rennell 

 was continually receiving fresh material, and six years later he 

 published a revised and enlarged edition {H in. to 1 degree), 

 and this was followed by further editions in 1792 and 1793. 



