ioo THE NEW WORLD OF SCIENCE 



after their delivery and to furnish thousands of prints over 

 night. With the advent of the film camera an additional trailer 

 equipped with a special film-developing machine was planned. 

 It is indeed probable that had the war continued much longer 

 the automobile photographic train might have been supple- 

 mented by railway photographic laboratories, so extensive had 

 photographic operations become. 



The proper mounting of the camera in the plane is of prime 

 importance. The first cameras were held in the hands, but 

 this soon became impossible, due both to the size of the cameras, 

 and to the airman's need for freedom to handle machine gun 

 and radio. Cameras were next " screwed " to the framework 

 of the fuselage, a method of support which proved quite un- 

 satisfactory, as half the pictures would be ruined by the vibra- 

 tion set up by the engine. Following this, various supports 

 of rubber and springs were devised along more or less scientific 

 lines, a chronic difficulty being the inadequate space available 

 for the camera and mounting. 



Finally an accurate method of study and test was developed 

 in the English Air Service, on the basis of which eminently 

 satisfactory mountings have been devised. This method con- 

 sists in flying over a light on the ground, either at night (or else 

 by day, with the light located in a dense wood), the shutter 

 of the camera being left open. There is thus obtained on the 

 plate a trail, smooth if the camera is steady, wavy if it is 

 vibrating. By means of a second intermittent light, flickering 

 at known speed, the duration of each kink in the curve may be 

 learned, and the suitability of the mounting evaluated accord- 

 ingly. 



Comprehensive tests of all kinds of mountings, supporting 

 the camera at the bottom, at the top, loosely and tightly, show 

 conclusively that the best form of mounting is that which sup- 

 ports the camera in the plane of its center of gravity (which 

 should not change as the camera operates), the supporting parts 

 being bedded in soft rubber or springs. 



After the aerial picture is obtained comes the question of its 



