Schermerhorn, Analogue (Classical) Photo gravimetrie Instruments 
Rotating the whole device over 90° Santoni brings the diapositives and the base 
bridge in a vertical position (Fig. 2). The first advantage is that the dimensions of this 
instrument are smaller than of the Stereocartografo IV nothwithstanding the fact that 
the model V takes 9" X 9" diapositives. This is the result of this special arrangement 
without the parallelogram of Zeiss in Z-direction, which would require a k x which is 
much larger than k y in model V. It also enables Santoni to use super-wide-angle photo 
graphy with full use of the available Z-range without extreme length of the Z-range for 
the 6^-bridge. 
Fig. 2. 
The most important advantage of this arrangement, however, is that the change 
from position with base inside to that with base outside requires only movements in 
opposite direction along the ¿^-column of the two gimbal joints. Consequently the kine- 
matical position of the instrument in successive models remains the same. The usual 
source of constant errors due to the difference between the positions of the instrument 
with base inside and outside is completely avoided. 
The design also greatly reduces the necessity for affine restitution for normal photo- 
grammetric work. If the possible change Ac of principal distance c goes from 80 to 300 
mm and the A Z-range is in a .cordance with the Ac-range, this instrument can take all 
near-vertical photography for aerial triangulation as well as for normal precise restitu 
tion. We consider this instruments as the most important new design which shows what 
can be achieved with application of the classical principles. 
4. Precision plotters. 
Also regarding these instruments, we see some changes in order to have full pos 
sibilities for the restitution of super-wide-angle photography. 
We have to mention first two new instruments of French design of SOM in Paris. 
These instruments are of the type with mechanical projection. The special qualities of 
these instruments are: 
1. the observation system relative to the plane of the diapositive is not submitted to the 
influence of the rotations qp and a>. The scanning movement takes place by means of 
Z-displacement of the diapositive and F-displacement of the optical system; 
2. in order to avoid jamming in the sliding part of the space rod in the image space, the 
image side end of the rod is replaced by movements of a system of two straight edges 
which are the projections of the space rod on two rectangular planes, passing through 
the optical axis of the photograph.