The lens 6’ makes the beam telescopic, and therefore suitable for 
employment of the Amici prism 5'. The beam carrying the observed image 
with stiil parallel rays is taken through the commutation unit 6'-7' 
respectively to the lens 7 and to the focal observating plane f. The 
eyepiece 8-9 (see fig. 7) is orthoscopic. 
In fig. 7 is evidenced even the disposition of the gears 1^, 2", 3". 4", 5". 
6", 1", 8", which have the task to eliminate, by means of the rotation of the 
Amici prism 5', the rotation of the observed image owing to the two ro- 
tations of the collimating gimbal around the principal axis aa. 
This disposition make sure for the observation that the orientation 
of the images of the photograms and their attitude are mainteined, this 
condition being necessary in order that the observation may take place 
irrespective of the various movements of the optical parts which depend 
from those of the mark, achieving thus the maximum stereoscopical effect, 
hy exploiting the whole parallact angle. 
d) The coordinatometric group and the system for the adjustment 
of the base. 
The group of the coordinatometer is composed of parts which allow: 
1) To transport in the space, according to the three instrumental 
directions, the system for the registration of the base according to the 
Zeiss jointed parallelogram. This means: adjustment in scale of the taking 
hase, and therefore possiblity of scanning the optical model; 
2) To project orthogonally on the three Monge planes (horizontal 
vertical and of the profiles) the virtual optical model obtained from the 
reciprocal and absolute orientation of the plotting cameras. 
In dependance from the two such tasks the group is formed: 
1) by the system for the adjustment of the base; 
2) by the system of the coordinate carriages. 
The first represented (see fig. 8) by a carriage which runs along the 
Y axis. 
The carriage supports a sledge parallel to the X of the coordinato- 
meter (by). On this sledge are mounted, in symmetrical positions two 
complexes, represented by two sledge slides at right angle to each other 
and orthogonal to bx. 
These units reiterate independently from each other the direction 
of the Y, Z axes of the coordinatometer, for the base adjustment. 
The base can be obviously adjusted both innerly and outerly, and 
the amount of its components, b, and b,, can be equally divided between 
its two ends, as well as they can be innerly adjusted from one side only. 
The amount which can be reached by the base components can be: 
for by, + 120 mm. (4?/,,"); for b, and b, + 50 mm. (1 au). 
The slide b, carries the support for the doubling gimbal, sliding along 
the collimating rod. The center of this gimbal together with the center 
15