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THE OPTICAL-MECANICAL CONDUCTION OF THE HOMOLOGOUS 
RAYS IN THE NISTRI PHOTOSTEREOGRAPH MOD. BETA 
by Commander Luigi Ronca 
In the photostereograph Mod. Beta the ray projecting in the model 
space the points of each photogram is identified optically by collimating in 
telescopic regime a mark with the point image of the photogram. For the me 
chanical translation to the coordinatometer of the direction as supplied opti 
cally by a collimater (mark at the infinite) the instrument employes the same 
rod which contains the optical device of the mark This position is so designed 
that the angular difference always existing between the optical direction of 
collimation, and the mechanical one as supplied by the rod, is kept largely 
within the instrument tolerances. 
The Author deals with the problem of the optical mechanical conduction 
of the rays in the new Nistri plotter under a double point of view. 
By giving an interpretation which one could term as historical, he deals 
in a comparative analysis with the passage from the first design of the photo 
stereograph model Alfa with the pancratic type devised then by Nistri, to 
the collimating rod as realised in the new model Beta. 
With another interpretation, which one could term as objective, the 
Author proves moreover how the solution which has made possible to keep 
the difference between the optical and mechanical directions within the 
conduction of the rays, issued directly from the resolution of a problem of 
statics put under a completely rigorous shape. 
The study is completed by analytical developments absolutely indis 
pensable to account for the main results, and hints at the main conditions 
for adjustment which have to be satisfied in the new telescopic collimation 
system of the plotter mod. Beta. With the given quantitative data as referred 
to the accuracies which can be obtained through it, the Author states that the 
collimating rod system inserted in Nistri’s telegonioscopical device represents 
decideily a step forward in the technic of the photogrammetrical plotting 
instruments. 
Of Nistri’s photogonioscope, which can be considered as a generali 
sation of Porro’s metrophotographic principle, the Author gives an interpre 
tation which evidence the features of simplicity of the new contrivance, 
specially for what adjustments are concerned. 
f) ORIENTATIONS POUR LA CONSTRUCTION D’APPAREILS DE 
RESTITUTION PHOTOGRAMMÉTRIQUES, par l’Ingénieur 
Santoni Ermenegildo. 
Le rapporteur se propose d’examiner les qualités indispensables aux 
appareils de restitution, au double point de vue économique et technique, 
pour arriver à établir quelles sont et combien sont les formules de solution 
à suggérer.