21 
— 2nd. Identification of the pairs of homologs in stereograms obtained from oblique take 
arrangements (take axes parallel) in which the coordinates of the nuclear points will 
remain in the above mentioned limits. 
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Fig. 15. Diagram for the use of the OMI Homologo-comparator for the identification of 
the homologous points in the oblique take arrangement. 
— 3rd. Being given the parameters of an intrinsically asymmetric ground take arrang- 
ement, the homolog-comparator allows the beforehand determination of the projectively 
corresponding zones on the two take frames. 
— 4th. Being given the two photograms of a stereogram of known reciprocal orientation 
and one or more pairs of homologous points, definitely recognizable, the homolog- 
comparator allows the verification of the accuracy of the data expressing the condition 
of reciprocal orientation. 
— bth. The points can be set or identified by pricking or by surveying the photographic 
polar coordinates. 
e) Performance as comparator. 
The function of orthogonal centesimal comparator is performed by the instrument by 
using the two orthogonal displacements also belonging to the primary function, one in 
direction of the projectivity axis of the carriage carrying the two points on which the 
intersection is undoubled, and the other normal to the first, attributing it instead to the 
larger carriage which supports the two frames, in respect to the projectivity axis. 
In preparing the instrument to function as a comparator (Fig. 11) it will suffice to 
slide out the two alidades from the sliding sleeves and insert them horizontally: one in a 
free position on the pair of sleeves pivotted on the nuclear points, and the other, the useful 
one engaged, instead, in the two sleeves of the undoubled intersections.