Bonn base
Coordinates: 50 ° 45 ′ 26 ″ N , 7 ° 3 ′ 57 ″ E
The Bonn base is a 2.1 km long geodetic base line that the Berlin general staff officer Johann Jakob Baeyer used as the basis for the Rhenish triangle survey. Its course is marked by three measurement points . At one of these points, in Bonn - Auerberg on Kölnstrasse on Josefshöhe , there is a cast-iron table with a memorial inscription in front of the neo-Gothic chapel (by Heinrich Wiethase , the builder of the Bonn collegiate church):
BASIS BONN 1847 / along the Kölnstrasse between Bonn and Hersel / was in 1847 under the direction of geodesist / General Johann Jakob Baeyer (1794–1885) / a 2134 m long route with iron measuring rods / measured to the millimeter. It served as the initial length (basis) for the Rhenish triangular network, which stretched from Aachen to Zurich and was used to determine the figure of the earth / as well as for land measurements. / For the alignment of the measuring rods and for plumbing / three 1.1 m high pedestals (A, B, C) were used, / whose former locations were marked in 1980 by cast iron plates / with the inscription 'Basis Bonn 1847' .
The graphic below the text shows that point A is just before Bornheim - Hersel , today (July 2006) marked by a manhole cover and a cast-iron table at the corner of Kölnstrasse and Friedlandstrasse in Bonn- Buschdorf (in front of a brick aedicule ). The "breaking point" B is marked today by a manhole cover next to the cycle path, about 20 m south of the way An der Landstraße (north of the north cemetery). Point C is in front of the Redemptorist monastery Josefshöhe and the associated Josephinum in Bonn . The proximity to the University of Bonn favored the choice of the survey base because the astronomer Friedrich Wilhelm August Argelander (Bonn survey ) taught in Bonn (earlier geodesists used star locations to anchor the positions in the graticule of the earth).
Baeyer writes about the concept of the “breaking point” (see web links: The Bonn base 1847 as a technical and historical monument): The northern end point was chosen near the village of Hersel, the southern one near the chapel about halfway from Bonn to Hersel, and the first with A, the last with C. Since the road is not straight, a third point B had to be assumed in the middle. All three points are on the western side of the road.
See also
- Baseline Unterföhring – Aufkirchen (1801)
- Baseline Schloss Solitude – Ludwigsburg (1820)
- Gaussian land survey , with reference to the triangulation (directed by Gauß himself) from 1821 to 1825
- Grossenhainer baseline (1870)
Web links
- The Bonn base from 1847 as a technical and historical monument (PDF file; 12.3 MB)
- The meridian point on the Venusberg. Archived from the original on November 4, 2011 ; accessed on January 26, 2016 .
- The Rhenish triangle network