THE TOPOGRAPHICAL SURVEY OF INDIA. 79 



that of one inch per mile ; the scale of half an inch 

 per mile being only resorted to in ^ery densely-wooded 

 or jungly country, containing few inhabitants and 

 little cultivated, or where the climate is so dangerous 

 that it is desirable to accelerate the progress of the 

 survey. 



On the scale of one inch per mile the practised 

 draughtsman can survey about five square miles of 

 average country per day. In intricate ground, inter- 

 sected by ravines or covered by hills of irregular for- 

 mation, the work proceeds much more slowly; on 

 the other hand, in open and nearly level country, or 

 where the hills have simple outlines, the work will 

 cost less and proceed more rapidly. On the scale of 

 one inch per mile all natural features (such as ravines 

 or water-courses) more than a quarter of a mile in 

 length can be clearly represented. Tillages, towns, 

 and cities can be shown, with their principal streets 

 and roads, and the outlines of fortifications. The 

 general figure and extent of cultivated, waste, and 

 forest lands, can be delineated with more or less pre- 

 cision, according to their extent. Irrigated rice-lands 

 should be distinctly indicated, since they generally ex- 

 hibit the contour of the ground. 



The relative heights of hills and depths of valleys 

 should be determined during the course of a topo- 

 graphical survey. These vertical elements of a survey 

 can be ascertained by trigonometrical or by baro- 



