Scale —————— 200m. 
Q O Points in the trian£gel net. 
Fig. 1 
the hidden sun was only 13° above horizon, even this very fast and 
rather grainy film was underexposed and had to be fully developed. 
The fairly hard wind (4 Beaufort) made the flight rather bumpy. The 
maximum shutter speed of 1/1.000 sec. could not be used. Three models 
of four (called A, B and C) were selected for the test. 
Geodetic Survey: A main net of 13 points (see Fig. 1) was accurat- 
ely measured by Thunberg with Wild T 2 theodolite and the scale of 
the net was determined by geodimeter NASM 4. A rigorous adjust- 
ment, which was performed in Facit EDB electronic computer (ma- 
chine-time 4 minutes) gave the point standard error of + 2,2 mm for 
X and + 1,6 mm for Y for the 13 points.