Photo gramme tria, XIX, No. U 
3. Universal plotters. 
Universal plotters, in general, do not show many changes. These instruments, such 
as Wild Autographs A7 and A9, Zeiss Stereoplanigraph C8, used in great numbers and 
in many countries of the world, seem to have given so much satisfaction to their users 
that the factory believes to do best by in future also producing the same model. The 
Nistri /?2 and the SOM Poivilliers B show minor improvements without changing their 
design in principle. 
There is one important exception: the complete remodelling of the Santoni Stereo- 
cartografo IV. The new model shows ingenious and important improvements. In this 
design Dr. Santoni has concentrated his experience gained in a 40 years’ carreer of 
designing photogrammetric instruments. 
The most important new feature of this instrument is a new arrangement of the 
relative position of the projectors, which allows continuous triangulation with base 
inside and outside without use of the classical design of the parallelogram of Zeiss. This 
is achieved by setting the diapositives not in their normal position in Z-direction along 
the flight line at the mutual distance k x , but on a line parallel to the F-axis. (Fig. 1). 
Santoni puts the diapositive t + 1 at a fixed distance k y to the right of the flight line. 
The base b x is imposed on a base bridge in Z-direction at a distance Z from the pro 
jectors. The space rods slide through gimbal joints on the base bridge. These joints 
have a mutual distance in Y equal to the constant distance k y between the centres of pers 
pecti vity of the two projectors. It is obvious that this distance k y needs not to be much 
more than the diameter of the projector. At the gimbal joints on the base bridge the 
small values of by and bz can be imposed.