58 SCIENCE IN AFRICA 



undertaken a variety of surveys on various scales from 1:4,800 to 

 1:250,000. In Northern Rhodesia an area of some 72,000 square 

 miles was mapped on the smaller scale for the Government for 

 general administrative purposes, and in 1930 the Northern 

 Rhodesia-Katanga Boundary survey was based to some extent on 

 their photograph work. They have also photographed a large area 

 of the Kavirondo District, Kenya, for prospecting companies, 

 in connection with the recent gold developments, as well as a 

 number of mining concessions in the Union and the Rhodesias. 

 They mapped another stretch of country for the Beit Railway 

 Trust which shows the Imperial Airways Route through Northern 

 Rhodesia. It must be stated, however, that these surveys are un- 

 contoured and therefore of small value for the development of 

 communications. 



These two companies have also interested themselves in the 

 possibilities of aerial survey in West Africa, and have made pre- 

 liminary inspections of parts of Nigeria and the Gold Coast. In 

 the Gold Coast heavy vegetation in the Colony and Ashanti would 

 probably make air survey impossible, or at any rate of little use 

 for mapping, particularly since maps on scales of i inch and 2 

 inches to the mile are already published for the whole area; but 

 an air survey of the Northern Territories has been proposed, 

 though it is objected by the Survey Department that sufficient 

 framework does not exist. In a few years, however, the primary 

 framework will be practically complete and, once this is so, a con- 

 centrated effort on topography would soon establish fixed points 

 which would be close enough to enable a survey from the air to 

 be satisfactory. The lack of prominent ground features might be 

 a difficulty, but this could probably be overcome by clearing small 

 areas of bush or making other marks which would show up oji the 

 photographs. The fate of air survey in the Gold Coast will depend 

 largely on the results obtained by prospectors who are now work- 

 ing on the undeveloped gold areas. If the fields are really valuable 

 the expense of air survey will probably be justifiable. 



The Air Survey Company has recently completed a very exten- 

 sive piece of work in the Sudan and Uganda for the Physical 

 Department of Egypt. It is concerned with the schemes for the 

 proposed Lake Albert barrage and the possible deviation of the 



