SCIENCE AND INDUSTRY. 
Aerial Photography and Surveying 
from the Aeroplane. 
By EWEN MACKINNON, B.A., B.Sc. 
The aeroplane owes its present prominence to the requirements of 
the great war, and but for that war its development would have been 
probably decades in reaching its present standard. It had few prac- 
tical uses before 1914. The whole situation has been changed, and now 
many different planes are made, each for its own special purpose. In 
1918 England was making twenty-three different varieties for naval and 
military work. 
—— 
THE “LB” TYPE AS MOUNTED ON THE AEROPLANE. 
Similarly with the art of photography, wonderful advances have 
been made, especially in aerial photography, which was an almost un- 
known field. The accounts of the evolution of acrial cameras and lenses 
during the war form a most interesting story, and reveal the fact that 
the optical and photographic firms of England, with official scientific 
Co-operation, produced new varieties of glass, new lens designs, and new 
types of camera which surpassed all others in existence. Lenses varying 
in focus from 4 inches to 36 inches were wholly made in England, and 
excel in every respect (in correction for spherical aberration and for 
Aspeme det, and in freedom from coma) any lens yet made by Zeiss 
or Goerz. 
In aerial photography one of the first difficulties to be overcome 
was the flat, hazy, and vague appearance of pictures taken from about 
a mile and a half up in places like Flanders. What was required was 
to overcome the lack of contrast or, if possible, to emphasize contrasts, 
e.g., over dark ploughed fields or great brown stretches of mud across 
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