27 
cross-slide system provided with digitisers. These are connected with the electronic control 
unit where the coordinates are stored and visually displayed (in l/l00mm or l/lOOO inch). The 
coordinates can be recorded in the form of a punched tape or card or in clear text. The 
recording is possible during the tracking, which is realised by freehand control. 
In the Aviograph B9, the polar pantograph has been modified similarly to that of the B8. 
Fig. 19. Wild B9 with instruction eyepieces. 
A new accessory, interesting for the purpose of training, is the instruction eyepieces (fig. 19). 
They facilitate a simultaneous observation of a stereo image by two operators (e. g. instruc 
tor and pupil). The second pair of eyepieces is mounted eccentrically (at the left) and is 
provided, as with the central eyepieces, with an x8 magnification. 
V. NEW COMPARATORS AND POINT TRANSFER DEVICES. 
In the period between 1964 and 1968, the following new comparators were constructed in 
Western Europe: the OMI-Nistri TA l/P, the Kern Monocomparator MK1, and the Galileo- 
Santoni Mono- and Stereo-comparators *). 
V. 1 Monocomparator TA l/P OMI-Nistri. 
The construction of the TA l/P is similar to one stage (half) of the measuring unit of the 
Analytical Plotter. The photo-carrier is adapted for 9" x 9" photographs and smaller, on glass 
plates or on a film base. Tracking is realised by the photo-carriage in x-direction and by the 
optical units in y-direction, The two pairs of cylindric guides are independent. The x- and 
y-lead screws are driven via electrical synchro-receivers. The electromotors for fast motion 
and the handwheels for slow motion, with the corresponding synchro-transmitters are 
physically separated from the measuring unit. 
*) The description of the Galileo-Santoni comparators was not available during the preparation 
of this paper.