36 
Consequently from (113) and (114) 
Qx X mm en (2 N 2h 1) (n ir 1) n Que + nQ, r- (n zs 1) N Qu, (117) 
nn 6 
p? 
Quy t e (2 n -- 1) (n 4- 1) n Q44 -- nQ,,, + 6 (n -- 1) n Q,, (118) 
n n 
Substituting the weight numbers (103)-- (106) (the correlation numbers 
are zero) we find after some rearrangement 
  
n 
Qr,x, RG (14 n? + 21 n + 25) (119) 
n 
Qy, vy = (10 2? + 15 n + 107) (120) 
n ) 
m Y == $9 J Q Y Y ( 122) 
s, is the standard error of the image coordinate measurements, which 
should be especially determined. The grid method according to HALLERT 
1957 is excellent for this purpose. With certain approximations the 
standard error of y-parallax measurements can also be used. In this 
way the standard errors of the center points of the photographs along 
the strip can be determined with respect to the points — 1,0 of the first 
pair of photographs. For intersected points along the strip the errors 
of the intersection have to be added to the errors of the principal points. 
The weight numbers of the intersected points with respect to the inter- 
section procedure can be determined as demonstrated in section 1.15 
above. A closer investigation shows, however, that the errors of the 
intersection procedure can be neglected after a few pairs of photographs. 
With a minor approximation, therefore, the expressions (121) and 
(122) can be regarded to be representative for the standard errors of 
the coordinates of a cantilever extension. The expressions are graphically 
demonstrated in the diagram 7 for s, = 1.