+ Download pdf (6.190 kb) - Nederlandse Commissie voor Geodesie

DE TWEEDE NAUWKEURIGHEIDSWATERPASSING VAN NEDERLAND
SUMMARY
THE SECOND GEODETIC LEVELLING OF THE NETHERLANDS (1926-1940)
Chapter l HISTORICAL DATA
1.1 Levelling before 1875
The Amsterdam Ordnance Datum (A.P.), reference datum for all levelling in The Netherlands,
was established in 1682, in Amsterdam, by means of 8 special benchmarks (Fig. 1).
Between 1797 and 1812, KRAYENHOFF [l41 carried out a level survey along the rivers ofThe
Netherlands and the coast of the Zuiderzee (Fig. 2). During the 19th century the Amsterdam
Ordnance Datum was also used in Germany as far away as Hanover and Kurhessen.
1.2 The first geodetic levelling, 1875-1885
The first geodetic levelling in The Netherlands took place between 1875 and 1885 partly in
response to a Prussian request to connect the A.P. to their levelling. This work was contribu-
tory to the establishment of the Netherlands Geodetic Commission.
The results were published in "Uitkomsten der Rijkswaterpassing" [20]. The network had a
total length ofmore than 2100 km (Fig. 3) and included 976 benchmarks. The level network of
Germany was linked at 5 places, as was the Belgian levelling.
1.3 Levelling in the period 1885-1920
In 1886 and 1887 the "Waterstaat" (Department of Public Works) added another 309 km of
levelling to the first geodetic levelling [16]. Subsequently the Department regularly carried
out secondary levelling. Since 1893 the reference datum has been referred to as N.A.P. (Nor-
maal Amsterdams Peil).
Information regarding all known benchmarks was regularly published by the Department
in the tables "Heights of benchmarks" [7] which were issued for each Province.
1.4 The layout of the tables and the numbering of benchmarks
The identification of the benchmarks has been changed several times over the years. Publica-
tions concerning the benchmarks from 1812 to 1931 ([14], [20], [16], [7], [g], and [9]) are de-
scribed in this paragraph.