1. Introduction 
GEOGRAPHICAL SURVEY OFFICE OF SWEDEN NO A 34 
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The adjustment of autographs is generally carried out in a series of steps 
using empirical methods. Since many of the orientation elements are correlated 
with each other, an adjustment based on this procedure clearly cannot give 
the best result. For this reason, a number of experiments [l] for performing 
the adjustment using mathematical methods were carried out prior to the Lis 
bon Congress. A very important advantage of a mathematical approach is that 
the accuracy of the autograph can also be determined. The principle for such 
tests was suggested by Hallert [2] . Hallert's method is called the Grid 
Method. As all the orientation elements were not included in [l] , the 
elements of the interior and exterior orientation could not be separated. 
This defect has now been remedied and the new test includes all the nor*- 
mally adjustable orientation elements in A7 and A8 autographs. 
2. The computational procedure. 
2.1 The orientation elements. 
The interior orientation in A7 and A8 autographs includes the following 
adjustable elements in each projector: 
A. The location of the principal point (the foot of the perpendicular from 
the projection centre) . The principal point is defined by the centre cross 
of the picture carrier. 
B. The principal distance (the length of the perpendicular). 
C. The location of the floating mark. 
The following notations for corrections are used: 
1. dXp ss the correction to the location of the principal point in the x- 
direction.