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THE NEW POIVILLIERS SOM STEREOTOPOGRAPHS TYPE B
by
Mr. Poivilliers.
No spectacular change has been brought into the Poivilliers SOM Sterco-
topograph type B.
This lack of important changes is due to the only fact that, these
machines giving full satisfaction to users for nearly fourteen years, it has not
appeared necessary to bring modifications into optical and mechanical parts,
with the sole purpose of “Making something new”.
However slight improvements have been brought to meet entirely the
needs created by new technics:
1. Some countries — among them the US.A. — having standardised
cameras, focal lenghts and photo sizes, the machine has been so modified as
to permit the plotting of such photographs. Special plotting cameras have
been designed.
2. The importance of the precise formation of the model becoming greater
with the development of traverse methods, and the appreciation of trans.
versal parallax correction having to be made from uneasy points of identifi-
cation, the transformation of this transversal parallax into stereocopic
parallax has been made easier.
The corresponding image rotation, which was operated by a pin, is now
controlled by a knob. This results in à gain of time when changing from one
mode of sight into another.
3. Millimetric distances are read in a meter placed below eye level, for the
operator’s convenience.
4. Carriages “x” and “y” may be disengaged.
5. The length of the rods has been increased, and the friction rollers set
about the front part of the carriages, thus enabling to increase the distance
and, as a consequence the plotting scale.
In particular, as regards cadastral surveys, that improvement permits a
diminution in the coefficient of amplitude in the co-ordinatograph.
6. The co-ordinatograph compounds two adjustable styles, which render
easier the joining up of drafts.
The styles are electrically lifted. A stereoscope, set side apart, is fixed on
the co-ordinatograph. It enables an easier drawing of a fair copy as well as
the checking of the survey.
THE COMPILATION INSTRUMENT USING RECTIFIED
PANORAMIC (OBLIQUE) PHOTOGRAPHS
The apparatus was constructed by the Société d'Optique et de Mécanique
de Haute Précision (SOM) based on the designs made by Geographic Engineer
Masson d'Authume.
It had been conceived in connection with the rectification instruments
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