18 
of a pair of homologe implies therefore the simple sliding of the carriage intersection, until 
one of the alidades passes through the set point A, on the image of one of the frames and 
therefore in the identification of its homolog A,, as intersection of the other alidade with 
the conjugated linear image that finds itself on the other frame. 
The bond of pertinence of each alidade to its nuclear point N and to its undoubled point 
H of intersection with the other is mechanically obtained by means of two sliding sleeves 
that are pivotted in each of the above said points. The set point on a frame and its homolog 
are searched for along the two alidades by means of two other sliding sleeves, fitted with 
à pricker or with a microscopic collimator according to if it is desired to survey the point, 
by pricking or by polar coordinates. As a matter of fact, on each of the frames it is possible 
to rest a polar coordinatometer for the survey of said coordinates. 
c) Identification of the homologs in the degenerate cases of the take dihedral. 
As already mentioned at paragraph I — (a), the identification of the homologs by the 
homolog-comparator can be accomplished by a very simple procedure, on stereograms ob- 
+ 
A pp 
  
X 
Fig. 11. Instrumental scheme of the OMI Homologo-comparator in the 
comparator arrangement. 
tained from take arrangements at parallel camera axes, and that is, when the take dihedral 
degenerates in a single plane or in a pair of planes. 
In the case of normal take arrangement, that is, with the photographic frames lying 
in the same plane, either if the base is horizontal, or with the base tilted, the two bundles 
of corresponding nuclear beams in their turn degenerate in a single bundle of improper