5 
RECORDING OF THE COORDINATES 
The recording of the coordinates is carried out through suitable 
encoders mounted on the six lead screws corresponding to the coordinates 
of the photographs. The encoders are able to count 1,000 pulses per 
revolution, i.e, one micron displacement, since the pitch of the lead 
screws is 1 mm. 
An electronic device counts the pulses and stores them so that the 
coordinates may be read at any given moment, either by reading directly 
from the dials or in the form of a clear record by a teletype machine 
or a punched tape. 
The recording on a punched tape is carried out in code on eight 
channels. When requested, the apparatus can be fitted with a recording 
system utilizing punched cards. 
Besides the six photographic coordinates of the points under 
examination, the apparatus also provides for the recording of 12 figures 
which serve to define the point itself. 
As in our preceding model, there is still the possibility of 
reproducing on a film the area under examination, and since in the 
reproduction the image of the mark will also appear, we can easily 
recognize the point to which the recorded coordinates refer. Furthermore, 
on the film, nine of the twelve figures characteristic of the point will 
appear, thus making it easy to single out the point on the photograph. 
A very important innovation with regards to the preceding model 
is the elimination of the hand-wheels which corresponded to each 
coordinatometer. There are now only two hand-wheels, one for the X 
coordinate, the other for the Y, while a series of buttons allow us to 
direct the movement of the hand-wheels themselves towards one or two or 
all three of the plates. 
Analogously for fast movements, which can be obtained by the use 
of appropriate switches which allow to slew (or transfer) the floating 
mark from one point to another of the photograph very fast. 
We have also planned for, although it has not yet been realized in 
the prototype just completed, the possibility of carrying out by pedals, 
instead of hand operations, the distribution of movements to the various 
coordinatometers, distributing automatically to the pair of photographs 
under examination, the movements obtained by using the hand-wheels. 
To sum up, the advantages which the new stereocomparator TA3/P 
offers over the preceding models are: 
(a) The optical observation is carried out beneath the photograph, 
placing the sensitive part of the film plates on the face of the film 
plate carriers, thus eliminating the necessity of adjusting the