Introducing these well-known formulae — in which Q';; and Q^; are the 
weight symbols of the measurements of z; and z/ — into (19) we obtain. 
QA, = (p + q) (Q m i + Q i+ 1 )— 4(Qo: + Qo’) fr 
  
  
+ FT (Qu, — 0») (20) 
| ; 1 
in which p = 7 =? the base-altitude ratio. 
It is emphasized that this formula holds generally, i.e. also for i; = 0 and 
i = n. It is true that — according to chapter 3 — the elements of relative 
orientation of the first and last pairs —1,0 and »,n-- 1 will not receive corrections, 
but this is not equivalent to saying that these quantities are “errorless”; it simply 
means that the influence of their errors will be absorbed by the other quantities 
which will indeed be included in the adjustment. 
c. Weight symbol of bi. 
According to chapter 3 the quasi-observation b/ is defined by: 
b'i=xi— xia 
in which x: and x';-1 represent the machine abscissae of the x-transfer points in 
the model i—1,.. 
The law of propagation of errors, applied to this formula, gives: 
Qu’; = Qo; = Qu 1 
Applying the well-known formulae which express Q;and Qz-, , in the 
weight symbols of relative orientation and the weight symbols Q's, and Q's 
of the measurement of the abscissae: 6 
Qo; = -— 200i a Qs, t Q's; 
Quia mz Qgy ra se QO, 4 
we obtain, considering that z — qb: 
Qv; 7 qb (—Qp, —Qqa) t Qy t Q— Qs, , (21) 
The weight symbol Q»; of the base bi in this formula can be reduced as 
follows: 
bi == b, fin pi Pa ect n pi—2 pi (22) 
whence, putting bo — b and f = 1 by approximation: 
i 
Q», =) | Q5]. 
Introducing this expression in (21), after having substituted Qg/ by (20) 
reading j for i, we obtain after some reduction: