14 
the adjustment procedure and the tolerances of the dt and dl have been com 
puted with the aid of the t-test. In general the level selected exceeds 5 percent 
which means that the confidence intervals have become narrower. For the 
confidence level 5 percent and 10 degrees of freedom, the following tolerances 
are computed for the autograph A7. The nine grid points in which the meas 
urements are made are assumed to be located usually in and around the prin 
cipal point forming a square, the sides of which are 200 mm. 
The tolerances of dt and dl become ±3.05q and ±3.2Sq respectively, where 
s' 0 is the standard error of unit weight of the projector coordinates according 
to the adjustment. For the tolerance values s' 0 = 7 microns the tolerances of 
dt and dl become ±21 and ±22.5 microns respectively. For the autograph 
A8 the nine points must be chosen in a rectangle around the principal point. 
Assuming a rectangular form with the sides 120 and 200 mm, the tolerances 
of dt and dl become ±3.9Sq where s' 0 is the standard error of unit weight of 
the projector coordinates. For s' 0 = 1 microns, the tolerances are found to be 
±27.3 microns. 
In the following tables some results of practical tests of an autograph A8 
are indicated. Shown in the first table are the test results before the mechanical 
adjustment, in the second table the results after the adjustment and another 
series of test measurements. This instrument is new and the basic accuracy 
is very good. 
Projector 
c 
mm 
z 
mm 
s o 
micr. 
dt 
micr. 
^max dl 
micr. micr. 
dlmax 
micr. 
Before the Adjustment 
Left 
150 
220 
2.8 
±12.0 
±11.0 
±40.3 
±11.0 
150 
320 
2.6 
- 2.3 
±10.2 
±33.4 
±10.2 
Right 
150 
220 
4.5 
- 8.7 
±17.6 
+ 24.1 
±17.6 
150 
320 
3.6 
±9.2 
±14.0 
+ 38.6 
±14.o 
After the Adjustment 
Left 
152 
304 
2.4 
± 6.1 
± 9.4 
- 6.1 
± 9.4 
Right 
152 
304 
1.9 
— 0.2 
± 7.4 
- 2.3 
± 7.4 
A very pronounced improvement of the geometrical quality of the instrument 
was reached through measurements, computations and mechanical adjust 
ment; the residuals are acceptable. 
For comparison the results of test measurements in an old instrument of 
the same type are shown in the following table.