40 
HISTORICAL EXHIBITION 
Exhibit 52 
the perpendicular passes through the eye-hole, thus giving the map po 
sition of the camera and its height. 
(Lent by the Ordnance Survey, Southampton). 
Fourcade experimental stereogoniometer, 1925. 
For setting two photographic plates in correspondence without compu 
tations. 
Exhibit 53* 
This stereogoniometer used pairs of photographs provided by two cam 
eras inclined to each other at an angle of 45°. This was done because, 
in the absence of a knowledge of the vertical, horizontal plates are badly 
conditioned for setting into correspondence. 
A feature of this instrument is the principle established by Fourcade of 
making the relative setting by pivoting the goniometers at their nodes, 
and rotating them about the exposure base, and about axes through the 
nodes at right angles to the exposure base. 
(Lent by the University of Cape Town). 
Photographs and maps of Pointe Lugano (Tivoli), 1919; Great Britain, 
1927; and Farnesina Rome, 1920. 
Lent by the Ottico Meccanica Italiana e Rilevamenti Aerofotogram- 
metrici SpA). 
Exhibit 54* Santoni stereocartograph, mod 1, 1926. 
A stereoscopic plotting instrument with continuous automatic tracing of 
both planimetry and altimetry. 
(Lent by the Istituto Geografico Militare, Florence). 
Exhibit 55* Panel illustrating the Canadian oblique method of mapping from high 
Exhibit 56 
oblique photographs, c 1923. 
Extensively used in Canada around 1923. The method was suitable only 
for flat country. 
(Lent by the Surveys and Mapping Branch, Department of Mines and 
Technical Surveys, Canada). 
Topographical stereoscope, type ZD4, c 1927. 
A grid stereoscope for 7 in X 7 in photographs developed by the War 
Office in conjunction with Barr and Stroud Limited, Glasgow, as a port 
able instrument for use in the field, primarily intended for qualitative 
examination of stereoscopic pairs of aerial photographs and parallax 
difference measurements in x and y. 
(Lent by the R. E. Equipment Branch, War Office, England). 
Exhibit 57 
Hugershoff Aerosimplex stereoscopic plotter, 1928. 
The two stereoscopic images are combined by back projection on a 
translucent matt screen for examination. 
Exhibit 58 
(Lent by the Deutsches Museum, Munich). 
Field-works stereoscope, type ZD 16, c 1929. 
A grid stereoscope for 5 in X 5 in photographs, developed by the War 
Office in conjunction with Barr and Stroud Limited, Glasgow, for use by 
the Royal Engineers in field construction work, particularly in the assess 
ment of gaps for bridging. 
(Lent by the R. E. Equipment Branch, War Office, England). 
Exhibit 59 
Topographical stereoscope and pseudoscope (precision model), c 1929. 
A precision grid stereoscope for 7 in X 7 in photographs developed by 
the War Office in conjunction with Barr and Stroud, Glasgow, having 
a special viewing system by means of which a stereoscopic pair of photo 
graphs may be viewed stereoscopically or pseudoscopically without 
removing the photographs from the instrument. Parallax measurements