172 



DISCOVERY 



Fig. 2. -a mosaic of ALEXANDRIA, CONSISTING OF 174 PHOTOS. 



mosaic, and tlie whole was then rcphotographed and 

 distributed to the various commanders. After the 

 war this method was employed experimentally for 

 town-planning purposes and for exploration work, 

 where it has been proved of the greatest possible use. 

 The British camera most generally used is con- 

 structed by Messrs. Williamson Brothers, the size of 

 the plate being 5 X 4 in. The cameras are of a fixed 

 focus type with long focus lenses. Panchromatic 

 plates are invariably used in order that correct colour 



rendering may be secured. Shutters are of the focal 

 plane type working directly in front of the plate. 

 Several efforts have been made to produce a type of 

 camera which will automaticallv expose a plate and 

 change it at definite intervals, so that the pilot will 

 have little to do except fly the machine, whilst other 

 attempts have been made to produce town plans by 

 means of kinematography. 



Apart from military requirements, the civil uses of 

 the aerial camera will be in town-planning and in 



