# Braak Base Line

> Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Braak_Base_Line
> Markdown URL: https://mediated.wiki/source/Braak_Base_Line.md
> Source: https://en.wikipedia.org/wiki/Braak_Base_Line
> Source revision: 1332662977
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

The **Braak Base Line** was the [baseline](/source/Baseline_(surveying)) for the state survey of the [Duchy of Holstein](/source/Duchy_of_Holstein), the [Danish state](/source/Denmark), the city of [Hamburg](/source/Hamburg) and the [Kingdom of Hanover](/source/Kingdom_of_Hanover) (Gaussian state survey). Its length was measured in 1820/21 by [Heinrich Christian Schumacher](/source/Heinrich_Christian_Schumacher) between the two [trigonometric points](/source/Triangulation_station) near [Braak](/source/Braak,_Schleswig-Holstein) in the district of today's Brunsbek in the district of Langelohe and [Ahrensburg](/source/Ahrensburg). After the reduction by [Christian August Friedrich Peters](/source/Christian_August_Friedrich_Peters) in 1853, the length was determined to be 3,014.45115 [toises](/source/Toise) (5,875.2747 meters).[1]

## Position

For the Danish survey, a route in a flat area was chosen:[2]

- Today, the North Base point [53.641096°N 10.209956°E](https://geohack.toolforge.org/geohack.php?params=53.641096_N_10.209956_E) is located at the transition between the [Ahrensburg](/source/Ahrensburg) site "Brauner Hirsch" and the Stellmoorer Tunneltal on private property, 51.2 meters above sea level.
- The South Base point [53.595904°N 10.255955°E](https://geohack.toolforge.org/geohack.php?params=53.595904_N_10.255955_E) is located between the villages of Braak and Langelohe on a field at 68.0 meters above sea level.

Observing the points from the [Michaeliskirche in Hamburg](/source/St._Michael's_Church,_Hamburg) and the Friedenskirche in [Siek](/source/Siek,_Holstein), which later burned down, resulted in the first major side of the triangle for the Danish and Hanoverian triangulation .

The points are still preserved but difficult to reach. The formerly open plain between the base points is now developed with the village of Braak, the [federal highway 1](/source/Bundesautobahn_1), the industrial area of [Stapelfeld](/source/Stapelfeld)/Braak and the residential area at the southern end of Ahrensburg.

## Cooperation

[Heinrich Christian Schumacher](/source/Heinrich_Christian_Schumacher) had a good relationship with the [Danish](/source/Denmark) King [Friedrich VI.](/source/Frederick_VI_of_Denmark), which enabled him to set up the observatory in [Altona](/source/Altona,_Hamburg) near Hamburg, which was then in Denmark. His teacher in [Göttingen](/source/G%C3%B6ttingen) was [Carl Friedrich Gauss](/source/Carl_Friedrich_Gauss). So Schumacher initiated the Danish king's request to the Hanoverians to let Gauss participate in the measurement of the baseline. Both were on location from 12. September to 25. October 1820 to combine the surveys of both kingdoms across the [Elbe](/source/Elbe) river. Gauss was thus able to forego his own length measurement.

Schumacher and Gauss were also in close contact with [Johann Georg Repsold](/source/Johann_Georg_Repsold). Schumacher used a base measuring device of his friend Repsold to measure the base. Repsold also made important contributions to the determination of the Altona meridian and the [meridian circle](/source/Meridian_circle) of the [Göttingen Observatory](/source/G%C3%B6ttingen_Observatory) (distance 7.5 [toises](/source/Toise) or 14.618 meters) in the form of his excellent instruments and improvements to existing instruments.

## See also

- [Borden Base Line](/source/Borden_Base_Line) (1831)

## Notes

1. Gerd Hoffmann, Karl-Heinz Nerkamp (2009). ["Heinrich Christian Schumacher – Der Altonaer Astronom und die Vermessung"](https://www.hamburg.de/contentblob/8025618/393cc7cbe73c9785bf4c65fad938736e/data/d-geschichte-schumacher-altona.pdf) (in German). *Hamburg, Landesbetrieb Geoinformation und Vermessung, GV Aktuell*. [Archived](https://web.archive.org/web/20210423175058/https://www.hamburg.de/contentblob/8025618/393cc7cbe73c9785bf4c65fad938736e/data/d-geschichte-schumacher-altona.pdf) 2021-04-23 at the Wayback Machine. Retrieved 2021-03-27.

1. ["Zeitreise: Die Vermessung Dänemarks und die "Braaker Basis""](https://www.ndr.de/fernsehen/sendungen/schleswig-holstein_magazin/zeitreise/Zeitreise-Die-Vermessung-Daenemarks-und-die-Braaker-Basis,zeitreise2732.html) (in German). *Schleswig-Holstein Magazin, NDR*. 2020-07-05. [Archived](https://web.archive.org/web/20210724064310/https://www.ndr.de/fernsehen/sendungen/schleswig-holstein_magazin/zeitreise/Zeitreise-Die-Vermessung-Daenemarks-und-die-Braaker-Basis,zeitreise2732.html) 2021-07-24 at the Wayback Machine. Retrieved 2021-03-27.

---
Adapted from the Wikipedia article [Braak Base Line](https://en.wikipedia.org/wiki/Braak_Base_Line) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Braak_Base_Line?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.