22 
Appendix. 
1.1. The measurements. 
The measurements have been carried out as shown on Forms A7:l and A8sl. At 
first, the grid must be placed on the picture carrier a little unsymmetrically 
in order to make an accurate measurement of point 5 possible. The distance 
between the centre cross and point 5 is chosen to be about 0.1 mm. The given 
values of the scales are set according to table 1. 2* , '~'0^00 is set by means 
of the grid, a ^/300.0 mm is defined by means of distance measurements bet 
ween points 2 and 8. The planes are measured in order, 1, 2, and 3* Because 
the z-differences are the given values, the z-values must be set very care 
fully by means of the height scales (the height scale for the A8 is 1:10 000 
and for the A7 Ba) . The measurements in every plane are performed in the 
following order: Points 1, 2, 3, 6, 5, C, 4, 7, 8, 9, 9, S, 7, 4, C, 5, 6, 
3, 2, and 1. Thus, 2 repeated settings are made in every point. The second 
setting is made from the opposite direction. Even some simple computations 
have been performed using Forms A7:l and A8:l such as the computing of the 
averages of the readings and the computing of the discrepancies in the image 
scale. 
1.2. The computations. 
The computations have been performed using Forms A7:2, A7:3, A8:2, and A8:3. 
We need Form A7:2 (A8:2) for each plane. This solution is presented in [l] . 
After computing three Form A7:2s(A8:2) the results as [v'v'] , the IT-values, 
dt, dl, X and T. dy' are transferred onto Form A7:3 (A8:3), where the 
final computations can be performed. The measurements and the computations 
are shown in detail in the following examples. The corrections to the common 
elements of the both projectors and the standard errors of the corrections 
can be computed according to the following formulas: