Travel theodolite
As Reisetheodolit one for is expeditions conceived geodetic theodolite called, built small and robust as possible and its adjustment on the move - d. H. without a workshop - is possible. The accuracy is between that of a second and that of a building theodolite .
Many such instruments were made at the end of the 19th century, for example by Starke & Kammerer in Vienna or Repsold in Hamburg. With the tilting axis of such theodolites, which was still constructed in an open construction, rectification after impacts or strong temperature changes was relatively easy to carry out. Small, padded wooden boxes with an edge length of about 15-25 cm were used for transport, in which the instrument could be anchored well.
The Scottish physicist Johann von Lamont (1805–1879) was an early pioneer of this optical and precision mechanical miniaturization . Inspired by Gauss and Humboldt to make geomagnetic recordings, he began around 1840 with the construction of measuring instruments for surveying and geomagnetics that were particularly suitable for the field . The constructed by him nonmagnetic Reisetheodolit ( nonmagnetic traveling theodolite ) ordered because of its special properties total of 45 observatories and research groups. Using this instrument and new magnetometers, he himself worked out precise maps of the Earth's magnetic field between 1844 and 1854 in Bavaria and then in Northern Germany .
In the 1930s , the inventor Heinrich Wild developed the miniature theodolite DKM1 at the Swiss instrument maker Kern Aarau , which, thanks to some fine mechanical innovations, had a height of only about 13 cm and was still almost a theodolite in terms of accuracy. The invention of the double circle principle for the two pitch circles and horizontal instead of vertical foot screws in the base of the measuring instrument contributed to this.
Today such small devices have lost their importance. On the one hand, transporting equipment to remote countries has become easier; on the other hand, terrestrial surveys are increasingly being replaced by methods of satellite geodesy with GNSS and GPS satellites.
See also
literature
- Franz Ackerl : Geodesy and photogrammetry , part 1 (instruments and methods of measurement), Verlag Fromme, Vienna 1950
- Heinrich Soffel: Johann von Lamont (1805-1879) - a pioneer of geomagnetism . Online also abstract , Paris 2010