3 
  
hoe == as 
Fig. 9. Genesis of the instrumental scheme of the OMI Homologo-comparator. 
b) Essential regulations in function of homologoscope. 
Having thereby obtained the instrumental scheme of the homolog-comparator, in which 
the generical intersection of two nuclear beams, along the axis of the projectivity, result 
undoubled by a segment equal to the relative translations of the undoubling above 
described. 
There can be observed that the two photographic perspectives are shown resting on the 
fundamental plane of the instrument, one with front face (emulsion) and the other with 
the posterior face (support), this implies the use of a positive plate and of the other 
negative plate. Renouncing however to the pricking on both, it will be possible to use 
both the negatives. 
The essential instrument regulation for its use will result therefore assured by the 
following measurable displacements: 
— displacement of the entire unit of the two plate carrier frames arranged on the 
alignment P P' of the two principal points of the axis of projectivity, perpendicular 
to said alignment so as to set the abscissa r in absolute value from the united fulcrum F; 
— angle displacement of each frame about the respective principal point for setting the 
two g, and g, swings in respect to the axis of homology; 
— orthogonal displacements u, and u,, v, 
coordinates in the respective systems that are mechanically bound to the single plate- 
carrying frames, and to the direction of the axis of the homology. 
and v, of the nuclear points for setting their