84 
120 
100 + 
  
  
   
  
  
    
  
T T T T T 
n n 2 n 2n an 7n n 
8 4 3 7 9 4 8 
Diagram 18. Ordinary aerial triangulation. Standard errors of the elevations. Bridging. 
sy = 1. 
This weight number and the weight number (333) are now added to 
the expression (329). Hence and for b — d 
p (n — p) h? 
Qn, Ry = {2 p (n — p) + 7} d 
6 nb? 
h? 
+ —>_— (52 + 5 p? — 2 pn) (348) 
4 b? n° ( C97 ! 
In order to obtain a simple expression for the accuracy the expression 
(348) can be transformed in different ways. 
With a minor approximation the following expression can be used 
for the demonstration of the error distribution under the assumed 
conditions 
p (n — p)»? 
= een 12 =‘) + 19! | 
Qn, Ry = 6 nb {2 p (n p) + 13; (349)