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When adjusting the photographs in the projectors, irregularity of distortion or of shrink- 
age of film is adjusted and averaged out on the feducial marks. 
The tolerances in the orientation depend naturally on the enlargement from negative 
to model and on the accuracy of the related plotting. In general, when the discrepancies 
between two opposite orientation points at the outer edges of the plate are more than 
0,04 mm in the model the numerical orientation has to be repeated. In case of doubt or 
in any special case the supervisor may be consulted. If residual parallaxes exceed the 
tolerances then the orientation can be repeated with the use of 9 instead of 6 points. If 
the result is still not good the material should be rejected. It is evident, however, that this 
is in many cases not possible and that the supervisor must find out, along which lines he 
can still obtain reasonable results. 
In view of the great variety in nature, scope and execution of various commissions there 
is little sense in giving a general statement of tolerances in determination of coordinates 
or in the absolute orientation and plotting on the drawing table. In alle cases the checks 
must be made and recorded by the operator. 
The numerical determination of coordinates is to a certain extent checked by comparing 
the x and y coordinates of common points in successive models. It is usual practice in this 
country to always approach the points for coordinate determination from the same 
direction. 
CHAPTER V. APPLICATION OF PHOTOGRAMMETRY TO 
OTHER THAN TOPOGRAPHIC PROBLEMS 
We regret that the position in 1960 is the same as that in 1956 and that photogrammetric 
methods are only in exceptional cases used for non-topographic purposes. The Geodetic 
Institute of the Technological University at Delft sold its Wild Autograph A 4 and cameras 
to the Hydraulic Laboratory at Delft which uses the equipment as mentioned in the 1956 
report. 
The other example of such an application, mentioned in 1956, has again been used in 
the launching of ships but with more suitable equipment, namely with a camera equiped 
with a special lens which gives an image of the full horizon. 
The most remarkable application has been that for the determination of the tracks of 
particles in a cloud chamber. After consultation with the I. T.C. and with Mr. H. C. Zorn in 
particular, Dr. A. van der Woude of Groningen University succeeded in constructing 
satisfactory equipment. 'l'wo cameras, f — 50 mm, negative size 24 x 36 mm are mounted 
in one frame in convergent position. The photographs are taken through 2 thick plane 
parallel glass-plate. T'he same cameras are used in the reprojection. In order to make this 
possible, condenser systems are built-in in the Twin Camera. The illumination unit can 
be fixed to the camera. It was Zorn's idea to avoid deformations by projecting the model 
through a plane parallel glass-plate, identical with that one used during exposure. A 
tracing table, similar to that of a Multiplex is used. X, y and z coordinates are recorded 
on punch tape. For the description see: A. van der Woude: "Construction and operation 
of Betatron and cloud chamber". Thesis of Groningen University (The Netherlands) 1960. 
31