32 
The standard error of unit weight from y-parallax measurements in nine 
points is then found from 
[vv] 
2 9 
Soo ^V — 7 
The standard error of the standard error of unit weight is about 0.35 509° 
The confidence limits are 
for the confidence level 5 per cent: 0.6 $09 ^ 2.9 S09 
I" " L u l per cent: 0.5 S99 - 4.4 $09 
2.6 Forms for the recording of y-parallaxes in fifteen points and for the 
  
  
computation of the standard error of unit weight. 
  
It has proved very valuable to use special forms for recording the y-parallax 
measurements and for various computations. Below, pages 33-34, some 
forms are demonstrated which have proved satisfactory. In particular it 
should be noted that in the form for computation of standard error of unit 
weight etc. valuable check is obtained, 
2.7 Form for the computation of corrections to the elements of the 
  
relative orientation for measured y-parallaxes in nine points. 
  
Also for the computation of corrections to the elements of the relative 
orientation special forms have proved to be very useful. An example of 
such a computation including determination of the accuracy of the correc- 
tions is demonstrated on page 35. 
{Pc 
  
Ox