INDIA 2 
The last two items were received through the United Nations Technical 
Assistance Administration. 
The following equipment received through the U.S. Technical Co-opera 
tion Scheme has arrived in India and is awaiting erection at the time of 
writing this report:— 
( i ) Wild Autograph, A.7 ... 
( ii ) Wild A. 8 Plotting Machines 
(in ) Zeiss Stereotopes 
(iv ) „ Rectifiers, S.E.Gf.V. 
( v ) „ Radial Secator ... 
2 
4 
1 ( 9 more on order ) 
2 
1 ( 18 more on order) 
A second Wild R.C. 5a aerial camera has also been received. 
The Indian Air Force, in close liaison with the Survey of India, is pri 
marily responsible for carrying out the aei’ial photography. When the 
demands for aerial photography are heavy a private firm, the Air Survey 
Company of India Ltd., Dum Dum, West Bengal, also carries out aerial 
photography under contract with the Government of India. From 1952 
to September 1955, the particulars of photography carried out, cameras used, 
etc., are as under:— 
Area covered with 
photography 
Cameras used 
Scale 
100,000 sq. miles 
( a ) Eagle IX, using 
1 ■ 58"=1 mile 
focal lengths of 
to 
6", 10" & 21" 
13-2"=1 mile 
( b ) R.C. 5a using a 
focal length of 
11-5 cms. 
Principal Methods.—As already stated, photogrammetric methods 
have only very recently been introduced in India but as more equipment 
is acquired, such methods will gradually replace the classic methods now 
employed for our mapping on various scales. 
Control.—For standard mapping at medium scales, horizontal control 
is obtained by triangulation and traverse methods. Vertical control is based 
either on trigonometrical or on level heights, depending upon the terrain and