115 
determined in connection with the computation of the standard errors 
of unit weight of the fundamental observations (image coordinates and 
parallaxes) for the actual degrees of freedom and for a certain confidence 
level. For the figures 10 and 5 % respectively, the confidence limits 
are about 0,7 and 1,80 times the standard errors respectively. 
The investigations refer mainly to vertical photographs. For con- 
vergent photography similar procedures can be used. The systematic 
errors of convergent photographs, however, are somewhat specific in 
comparison with vertical photographs. Therefore some types of such 
errors were theoretically determined and demonstrated in a number of 
diagrams. 
Acknowledgements 
The first draft of the manuscript was read and very useful criticism 
and advice offered by Mr. G. GALVENIUS and Mr. L. G. OrT0s0N, both 
civil engineers. I also gratefully acknowledge the help of Mrs. GUN 
FAGERHOLM and Mrs. EvA WERNHOLM. 
Financial support for the investigations has been received from 
Swedish Technical Research Council. 
A LE 
PRISES BI 
GN RE AE GOGH SEIEN NEN ARIES