GREAT BRITAIN 6 
suitable first degree. 
Research 1ms been done in investigating the distortions 
caused by temperature differences in aircraft camera windows 
and in the air spaces in front of the camera lens; and the 
deformation of photographic plates. Dr. E. A. Miskin has 
done considerable work on the application of photogrammetry 
to medical problems. 
The Ministry of Supply has placed a contract with a 
University to conduct research into the causes and cure of 
marking of camera film due to electro-static discharges. 
The Ordnance Survey has done appreciable research into 
the analytical method of aerial triangulation (14)> and on 
the application of electronic computing to the reduction of 
observations made in the stereocomparator (2). A parti 
cular development has been the use of two blocks of photos 
of the same area, one at a scale of about 1/20,000, 
adjusted to the ground triangulation, and providing controls 
for the second block at about 1/4,000, for mapping at 
1/1250 (13)« The medium scale block provides internal 
consistency, whilst the large scale provides local accuracy 
in the interpretation and fixation of minor controls for 
plotting each overlap. The method shows promise; it is 
already accurate enough for 1/2500 scale, and nearly so for 
1/1250. It shows an economy compared with the ground 
survey of equivalent controls. As regards computing, the 
'’stereograms'* (overlaps) are solved completely by electronic 
calculator, and it is hoped soon to form strips in this way 
also. The formation and adjustment of blocks is done 
graphically, and is likely to remain so for some time yet. 
5. REFERENCES 
(references) 
(AU3KUNFT) 
Professional Papers of the Ordnance Survey - NE.V SERIES 
(published by K. M. Stationery Office, London) 
i. No. 20 
"A Stereocomparator Technique for 
Aerial Triangulation” 
by D. G-. Arthur F.R.A.S.