Württemberg land survey
Württemberg State Surveying refers to the surveying and mapping of the state carried out in the Kingdom of Württemberg from 1818 to 1840 .
history
As a result of the upheavals of the Napoleonic era, the state of Württemberg , which was elevated to a kingdom in 1806 , had increased to 19,514 km² by 1810, a good double the area of 1801. According to the large number of previous rulers, there were very different property registers in the various parts of the country in terms of scope, structure and accuracy . These - mostly referred to as goods, warehouse or tax books - served two purposes: on the one hand, as the forerunners of today's land register , they served to record all legal transactions associated with the land (sale, pledging, easements ), on the other hand they were an important tool for the collection of property tax . In order to be able to set the tax not arbitrarily but according to a comprehensible system based on the size, use and income value of the land, the books had to be standardized and all areas had to be measured precisely. In the kingdom, which at that time was dominated by agriculture, no further applications of surveying were in mind; But they should soon gain in importance (road and hydraulic engineering, railway construction from 1845).
King Wilhelm I , ruling since 1816 and determined to transform Württemberg into a modern state, ordered the land surveying by decree on May 25, 1818. He appointed his finance minister, Ferdinand Heinrich August von Weckherlin, to head the authority established for this purpose, the cadastral commission . The Tübingen professor Johann Gottlieb Friedrich von Bohnenberger took over the scientific management , the organization was in the hands of surveying conductor Franz von Mittnacht (1781–1849).
The surveying work begun in the autumn of 1818 near Tübingen , the technical implementation of which was based on the experience gained in Bavaria since 1801 and Bohnenberger himself with the Swabian charters since 1795, lasted until July 1, 1840. An average of 90, a total of 500 surveyors were in Employed on behalf of the royal "Statistical-Topographical Bureau". The total costs amounted to 3,820,000 guilders , which corresponded to around 40 percent of an annual budget of the state at the time .
Geodetic reference system and triangulation
Fundamental point
Bohnenberger set his observatory in the north-east tower of Hohentübingen Castle as the fundamental point and zero point of the Württemberg coordinate system , and determined its geographic coordinates as follows:
Triangulation
Bohnenberger mostly determined the angles of the main triangles himself and was almost able to complete this task by his death in 1831. The calculations were based on an ellipsoid of the earth with a major semi-axis of (in today's unit) 6,376,604 m and a flattening of 1 / 312.7. For the main and secondary network he applied the formulas of spherical trigonometry to a sphere approximating the ellipsoid. The triangular network comprised a total of 32,760 signal points, 75 of which were in the main network.
Direction determination
To orient the triangular network, Bohnenberger determined the azimuth of the Tübingen – Kornbühl route . In doing so, he went back to the measurements he had made in 1792 as a preliminary work for the Swabian chart , which later turned out to be not entirely accurate. Therefore, the abscissa of the Württemberg coordinate system is rotated by about 16 "to the east compared to the north direction of the meridian.
Basic measurement
In 1818 Bohnenberger intended to base the length data of the surveying works on the measurement of a 13-kilometer base line on the Solitude-Allee, which was laid dead straight in 1768, between Ludwigsburg and Solitude Castle . However, the delivery of the copy of the Toise du Pérou ordered in Paris , which was absolutely necessary for the calibration of the measuring rods, was delayed . In order not to have to postpone the start of the piece measurement any longer, in April 1819 the existing - not calibrated - tools were used to measure an approximately 5 km long "auxiliary base" in the Ammertal near Tübingen, whose length of 17,499.07 feet was the basis for all subsequent calculations .
After the Toise from Paris had finally arrived, the measurement of the " main base " on Solitude-Allee was carried out on September 18, 1820 and an unpleasant surprise was experienced: 45,491.30 feet were measured, while the calculation from the auxiliary base had a length of 45,501.64 feet was expected. There was only one explanation for the large deviation: The measuring rods used for the auxiliary base were too short and therefore the dimension figure too large. It was already too late for the actually obvious solution, namely to correct the length of the auxiliary base and all values based on it, because the piece measurement was in full swing and was working with the "wrong" coordinates. So Bohnenberger had to resort to two tricks. He retained the dimensions of the lengths built on the auxiliary base, but replaced the unit foot with the land survey foot (one LV foot equals 126.97 Paris lines). He eliminated the remaining error by reducing the measured length of the main base (in the new unit equal to 45,502.05 LV feet) to the ad hoc introduced land surveying horizon of 840 Paris feet (around 273 meters) above the sea horizon. This makes the Württemberg surveying system the only German surveying system whose lengths do not refer to sea level. The parallel use of two units of measurement (LV foot for the coordinates of the triangular points, legal foot for piece measurements) only came to an end with the introduction of the meter rule on January 1, 1872.
Württemberg coordinate system
There are Soldner coordinates used with zero Tübingen. When converting to other coordinate systems ( e.g. Gauß-Krüger ), the above-mentioned twist and the deviating horizon must be taken into account in advance.
Maps
Land map 1: 2,500
As a visible result of the piece measurement, in addition to the uniform goods books and the so-called primary cadastre, the Württemberg land map was created . From the beginning it was used as a frame map on a scale of 1: 2,500. The right and high values (Soldner coordinates shown as flat Cartesian coordinates ) of the respective edge lines represent integer multiples of 4,000 land survey feet, so that each land map appears as a square with 45.83 cm side length. Starting from the zero point in Tübingen, the map sheets are labeled with a quadrant (NE, NW, SW or SE), "shift" (row) and "row" (column). A total of 15,572 land maps were recorded. The reproduction was initially carried out using lithography , and since the 1930s mainly using the blueprint process .
Topographic Atlas 1: 50,000
The Royal Statistical-Topographical Bureau , founded in 1820, immediately started the topographical survey of the country , which was based on the cadastral survey. The original sheets were used as work maps, consisting of ten by ten field maps reduced to a scale of 1: 25,000, in which the terrain slopes measured or estimated with simple instruments were entered. The map of the terrain was done in the form of hatches using the Lehmann method . By reducing four original sheets to half size and putting them together, a sheet of the Topographical Atlas 1: 50,000 resulted, which thus covered the area of 400 land maps. The first of the 55 atlas sheets appeared in 1826, the last in 1851. The first edition could not provide exact height information, because the trigonometric height recording did not begin until 1859, a systematic geometric leveling even not until 1868.
See also
literature
- Land survey office Baden-Württemberg (publisher): 150 years of Württemberg land surveying. Land surveying office Baden-Württemberg, Stuttgart 1968.
- State Office for Geoinformation and Rural Development Baden-Württemberg (Ed.): 200 years of land surveying. CREATING THE BASICS. State Office for Geoinformation and Rural Development Baden-Württemberg, Stuttgart 2018, print number MLR 19-2018-43 (commemorative publication for the 200th anniversary).
- Alfred Egerer: The mathematical foundations of the Württemberg maps. In: Württemberg year books for statistics and regional studies. 1930/31, ISSN 0721-1589 , pp. 287-420.
Remarks
- ^ Source: Statistical-Topographical Bureau of the Kingdom of Württemberg, sheet NO XXXVIII / 6, Landesarchiv BW, Staatsarchiv Ludwigsburg
- ^ Rudolf George: The Württemberg land survey (1818-1840) and the time before. In: Heimatkundliche Blätter Balingen, 33rd year 1986, issue 1, pp. 529-532, here p. 531.
- ↑ In 1806 the Württemberg foot was legally set at 127 Parisian lines .
- ↑ Source: Statistical-Topographical Bureau of the Kingdom of Württemberg, sheet NO I / 1, Landesarchiv BW, Staatsarchiv Ludwigsburg
