The Siegfried Map

The Dufour Map was a masterpiece of surveying and cartography. But the young Federal State soon developed new needs: a booming economy, a growing network of infrastructure and an administration, which was constantly covering new areas of human interaction, needed ever more precise spatial information.

In 1868, three years after the Dufour Map was completed, Parliament established the legal basis for a new map to meet the new challenges. The “Swiss Topographical Atlas”, also known as the Siegfried Map, showed Switzerland to a larger scale than the Dufour Map: 1:25 000 (Swiss Central plateau) and 1:50 000 (Alps and Jura).

It thus offered a lot more space in order to integrate information about topography, residential settlements, infrastructure and rock formations into the map. The newly added contour lines and tricolour printing further increased the informative value of this second Swiss map.

Geodetic points and Heights

The Siegfried Map sheets were published over a period of almost 60 years. Many important changes occurred in Swiss national topography during this time. These developments can be summed up by an increase in precision and new technological processes.

Three base line measurements 1880/1881, the LV03 national triangulation network (1903–1939) and two levellings (1865–1883, 1903–1927) determined the geodetic surveying points and the altitudes in Switzerland with increasing precision.

The constant improvement of altitude measurements is also reflected in the fact that the Swiss height reference point in the harbour of Geneva was redefined: It “sank” from 376.86 to 373.6 metres over the Marseille water level.

Photographic Processes

Like the altitudes, which were only included in the National Maps following their redefinition, topographical surveying methods also evolved.

After the First World War, work at the surveying table increasingly gave way to photographic processes: the topographers took stereo pairs from the ground, which they could then process in their offices. This “photogrammetric process” developed over the following decades into a key technology for surveying Switzerland.

Publication of first sheet (no. II) of the 1:250,000 general map.

Swiss Alpine Club successfully campaigns for adoption of legislation governing the continuation and publication of the original surveys.

Publication of the first 13 sheets of the 1:25,000 and 1:50,000 topographic atlas (Siegfried Map). 

Publication of 1:1 million overview map. 

Hermann Siegfried calculates the altitude of the R.P.N. control point in Geneva as the starting point for height measurement based on precision levelling elements (but with the previous reference height of the Chasseral dating from 1840) as 376.86 metres above sea level (also referred to as "old horizon"). This figure is applicable for all published sheets of the Siegfried Map.

Aarberg base line measurement by Spanish General Ibañez as part of the central European arc measurement. 

Publication of first maps with relief shading (Oberland I and Jaun-Thun sheets, 1:50,000). 

Commencement of systematic surveys of the national borders. 

Altitude of R.P.N. control point in Geneva calculated by Jakob Hilfiker (based on associated levellings from abroad) as 373.6 metres above sea level (referred to as "new horizon" and used as initial height for the national map). Starting point is mean sea level of Marseille (France).

Commencement of first national levelling (until 1927).

Max Rosenmund proposes oblique, conformal cylinder projection for surveying Switzerland (= CH1903).

Federal resolution on the land register survey (in conjunction with the Swiss Civil Code that entered into force in 1912). 

Initiation of transfer of production of mountain map sheets from lithography stone to copper plate.

Introduction of offset printing. First own machine supplied by George Mann (Leeds, UK). 

Entry into force of the Swiss Civil Code, which calls for the creation of a land register with corresponding plans.

Swiss Geological Commission petitions Federal Council for a 1:25,000 map of the entire country.

Recruitment of first pilots for aerial images. Oblique images photographed by hand from open aircraft (Zepp C.II). Instruments provided by Zeiss. 

Definitive introduction of terrestrial photogrammetry in the Alps. Acquisition of two valuation instruments and four cameras supplied by Wild.

A total of 604 sheets of the Siegfried Map have been published: last sheet to appear, 274bis Gaschurn.