The Survey Department of Rijkswaterstaat will have carried out triangulation for 
several isolated strips for the construction of roads, highways and canals (type a). The strip 
triangulation, however, of the Cadastral Service is only strip triangulation, because no 
block adjustment has been applied and belongs therefore to type b. What K.L.M. Aero- 
carto mentions as strip triangulation are really isolated strips. 
III. 3. Aerial triangulation in Institutes for education and research 
Coming now to the activities of each individual institute or service we start first with 
those mainly established for education and research, namely the Geodetic Institute of the 
Technological University at Delft and the I.T.C. The execution of triangulations in space 
with the instrumental method was part of the Netherlands contribution to the programme 
of the Commissions A and B of the OEEPE. The instrumental triangulations were carried 
out almost entirely on the equipment of the I.T.C. by staff members of this organisation. 
Through the contribution of the Geodetic Institute of the Technological University the 
electronic computer of this University became available for the computations, which were 
carried out mainly with the cooperation of staff members of the Survey Department 
of Rijkswaterstaat and the I.T.C. For results and further details about this OEEPE 
programme the OEEPE will give some information in an invited paper in the third 
Congress number of Photogrammetria. After the Congress a special OEEPE number 
of Photogrammetria. will give full details about the work carried out in the past four 
years. 
The instalment of the Wild stereocomparator in the I.T.C. laboratory in October 1959 
was a very important step forward, since this enabled Delft to start with experimental 
work in analytical (digital) aerial triangulation. The measurement of plate coordinates 
for aerial triangulation has started on strips of the OEEPE Commission A which have 
already been measured in universal plotting machines. Furthermore a block of 10 strips 
of photographs in the scale 1 : 20.000 taken for the Netherlands Topographic Service was 
also measured on the stereocomparator. This block is being done in cooperation with 
Prof. Roelofs (triangulated on the Wild-Roelofs radial triangulator RT 1) and with 
assistance of photogrammetrists of the Military Topographic Service, Delft. The machine 
coordinates of this block, obtained by both methods will be adjusted with the 1.T.C. Jerie 
Analogue Computer. It is doubtful whether the computation can be finished entirely before 
the London Congress. 
The production of the stereocomparator was between 7 and 10 pairs per shift of 6 hours, 
depending on the number of points. We experienced that it is very useful to have the 
plates prepared in advance by an assistent, who indicates with glass pencil all points on 
the glass side of the plate and connects these points by lines. This preparation avoids all 
searching for points, which is important because of the small field of view of the stereo- 
comparator. The number of points observed in each pair was between 20 and 30, including 
the four fiducial marks and the 6 orientation points. Unfortunately this block of Nether- 
lands photographs has no record of camera orientation instruments, no horizon camera 
and no statoscope. Consequently the result of this test cannot be considered to be the 
ultimate precision which can be obtained with the present day available means. Since 
however there exist in the world such a tremendous number of photographs taken under 
the same conditions this test can be considered as important for the evaluation of what 
can be obtained in similar terrain under similar circumstances by the analytical triangula- 
tion as well as by means of precise radial triangulation. 
Regarding the further activities of these two educational and Research institutes no 
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