98 THE NEW WORLD OF SCIENCE 



of pilot and observer, leaving them free for other duties. Plate 

 magazines, carrying from six to a dozen plates, operated by a 

 simple to-and-fro motion shifting the exposed plate behind the 

 pile of unexposed, were generally used by the French and 

 Germans. The English early designed and used to the end a 

 system of two magazines, one above the camera containing the 

 unexposed plates, another to one side and lower, over which 

 the exposed plate was shifted and allowed to drop. Cameras 

 of this type, known as the " C " and " E," operated by hand, 

 were ultimately followed by the " L," in which the operation 

 of shifting the plate and setting the shutter was performed 

 by a wind propeller. In this " semi-automatic " camera the 

 pilot or observer had merely to pull the exposing lever at the 

 appropriate instant, after which the camera set itself ready for 

 the next exposure. These cameras, using 4x5 inch plates, 

 formed the greater part of the equipment of the English Air 

 Service, and close copies were manufactured and used in large 

 quantities in the training of some thousands of American aerial 

 photographers. 



The demand for completely automatic plate cameras, which 

 would require no attention save starting and stopping, was 

 perhaps most nearly met by the French de Ram camera. In 

 this was embodied a rotating magazine containing 50 plates, 

 the lower one of which was exposed, dropped off and picked 

 up by the top of the magazine as it rotated. Cameras of this 

 general design were under construction in considerable numbers 

 in America at the close of the war, and promised to be the most 

 complete and satisfactory plate camera yet devised. 



A serious limitation to all plate cameras for aerial use lies 

 in their weight and bulk. Thus the de Ram camera above 

 described weighs, with its load of plates, about 100 pounds, and 

 stands over three feet high. Such a weight seriously interferes 

 with the balance and ceiling of the ordinary two-passenger 

 reconnaissance plane, and is quite, out of the question as an 

 extra load in a single-seater scout. This matter of weight and 

 space became so aggravated by the general adoption of 50 



