Its original height, the so-called «old reference», of 376.86 m above the mean sea level of the Mediterranean (tide gauge in the harbor of marseilles) was determined in the 19th century from the height of Mount Chasseral, which had been determinded inaccurately by French engineers and geographers from the tide gauge in Marseilles. This original height was used for the old height ovservations (precise levelling 1864 to 1891) as well as for the Dufour and the Siegfried Maps.
Height reference for Switzerland
The reference for all height measurements in Switzerland is the «Repère Pierre du Niton» in the harbor of Geneva. It is used for all surveying and maps in Switzerland.
- Repère Pierre du Niton: vertical control point on a rock in the harbor of Geneva. It serves as the fundamental height reference for all surveying in Switzerland.
At the beginning of the 20th century in the scope of the national survey, this reference was redetermined. In 1902, an investigation by J. Hilfiker was published in which the height of the «Repère Pierre du Niton» was computed from different tide gauges in Europe. The official value of 373.6 m, the co-called "new reference" thus introduced in 1902 and was a total of 3.26 m lower than before!
Therefore, the old heights, i.e. in the Siegfried Maps are 3.26 m higher than the official heights in the national maps and in all cadastral plans in Switzerland. Despite concerted efforts to inform professional organisations of this change, the actual implementation of the new height progressed only very slowly, especially in civil engineering and in the construction industry, which has often led to mistakes and confusions concerning heights.
Definition of the reference 1902
- controlled by four connections to sea level
- derived from the tide gauge in Marseilles and rounded to 373.6 m ASL
Applications Repère Pierre du Niton
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