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cases the surface to be tested must not deviate from a flat surface more 
than 0.00002 inch per linear inch and all points of the surface shall be 
between two parallel planes separated by 0.0004 inch. In other cases the 
tolerance of flatness is reported to be 0.02 mm. 
In general the organizations seem to be satisfied with the tolerances for 
flatness as given by the manufacturers. 
4.1 How are the tests at the delivery in principle constructed and performed? 
4.11 As tests of the individual construction details ? 
How are in such a case the straightness of lines and the flatness 
of surfaces in the instrument tested ? 
Which are the tolerances and how are they constructed ? 
4.12 As integrated tests (only one or in a few steps) from projectors 
to coordinate counters and coordinatograph respectively ? 
How are in such a case, possible systematic deformations of the 
projected bundles of rays tested? 
Are the tests also applied to base out and base in? Tolerances ? 
4.13 In some other way - for instance as a combination between 4.11 
and 4, 12? 
28 answers. 
The test is mainly performed as integrated test of the instrument after 
delivery with grid measurements (27). 
In general the adjustment-tolerances given by the manufacturer are used. 
In some cases (6), however, tolerances (standard error) of 0.005-0.01 mm 
of the x-and y*coordinates in the image plane, 9 or 45 points, and a standard 
error of height of 0. 01-0. 1 ?/oo of the flying altitude is allowed for the 
precision instruments. The tolerance of the coordinatograph is 0.1 mm. 
The test is when possible performed for base in, base zero, and base out 
and for some different principal distances. 
In 4 cases the test is also performed on the individual details, as straight- 
ness of lines (tolerance 0.01 mm), flatness of cassettes (tolerance 0. 0005"), 
flatness of drawing table of Kelsh Plotter (tolerance 0.01"), 
The test is in general performed by the operator in chief but in 4 cases by the 
manufacturer only. 
4.2 How frequently are the geometric qualities of the instrument checked 
during practical work and how are these checks performed? 
Which are the tolerances and how are they constructed? 
4.21 Which tolerances are allowed before mechanical adjustment of the 
most common systematic errors as for instance errors of the 
principal distance, errors in the position of the principal point, 
x-inclination and latitude distortion etc, ?