Adolf Fennel

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Adolf Fennel (born March 7, 1860 in Kassel ; † March 1, 1953 in Kassel) was a German industrialist for surveying instruments.

Life

Adolf Fennel, the older son of the precision mechanic Otto Fennel (1826–1891), first attended the higher trade school in Kassel , a polytechnic . Actually, he would have preferred to study natural sciences, but in 1877 he had to join the company for optical instruments founded by his father on June 23, 1851, where he trained as a precision mechanic. In 1891 he and his younger brother Otto took over the management of the company, which he led under the name "Otto Fennel Sons" to become a company of international renown.

Fennel's Estimated Microscope Theodolite (1903)

Adolf Fennel is one of the most important designers of surveying instruments. He paid particular attention to increasing the accuracy of circular readings, the manufacture of circular dividing machines and instruments for optical distance measurement for cartographic purposes. The scope of his technical work is characterized by around 50 publications and 12 patents. Adolf Fennel had always retained an interest in the natural sciences, and even before he took over the management of his father's company in 1891, he maintained an intensive exchange of experience with scientists in various countries. This laid the foundation for numerous new developments. For example, from 1900 he worked on an estimation microscope theodolite on behalf of Carl Reinhertz , Professor of Geodesy at the Technical University of Hanover since 1899 , with an index thread for circular reading in the image plane of the microscope. Since two degrees were always visible in the field of view, the reading could be done quickly and reliably, and due to the sufficient size of the image, the estimate could be made with an accuracy of 1 '. In 1902 this theodolite was perfected to such an extent that it came on the market. In the vernier microscope (1912), based on an idea by optics entrepreneur Moritz Hensoldt from Wetzlar , there is a vernier in the microscope image plane and enables a further increase in reading accuracy. The conclusion was the precision measuring or plane glass microscope (1930), in which a rotatable plane-parallel glass plate is inserted in the beam path near the objective, through which the image of the graduation can be shifted optically in parallel so that a graduation falls in the middle of the double adjustment line . The plane-parallel plate moves with one arm a scale located under the upper part of the image field, on which the shift of the graduation caused by the plane plate can be read immediately on the index line, with an accuracy of up to 2 ".

To increase the partial accuracy of partial machines, Fennel devised a mechanical compensation through which the periodic errors in the toothing of the nut division are rendered harmless. The "Wagner-Fennel Tachymeter " (1882), an improved version of the tachygraphometer first introduced by Ing. Karl Wagner in 1868, enables the readings of horizontal distances and height differences from inclined observations with the help of a mechanical reduction. The "Hammer-Fennel reduction total station", on the basis of which Ernst von Hammer , Professor of Geodesy at the Technical University of Stuttgart , had worked since 1893, uses a diagram to determine these values. The curves of this diagram are the basis for the construction of the total station chart of all manufacturers and founded the development of this type of instrument in 1898, which is characterized by its particular economy and high accuracy. A wedge distance meter was patented in 1928 as a "double-image rangefinder". From the range of magnetic instruments, an orientation magnetometer is worth mentioning (1893), which allows instruments to be set to magnet north with great accuracy.

Honors

In 1922, Adolf Fennel was from the Technical University of Stuttgart , the honorary doctorate awarded.

Fonts

  • Preliminary information about a new declinatorium for orientation measurements and about a new variometer. Craz & Gerlach Publishing House, Freiberg in Sachsen 1894.
  • The Wagner-Fennel total station of the factory of geodetic instruments by Otto Fennel Sons in Cassel - third improved edition. Published by Konrad Wittwer , Stuttgart 1904.
  • Geodetic instruments. Book 1: Leveling Instruments. Published by Konrad Wittwer , Stuttgart 1910.
  • Geodetic instruments. Book 2: Nonien Theodolites. Published by Konrad Wittwer , Stuttgart 1911.
  • Geodetic instruments. Book 3: Microscope Theodolites. Published by Konrad Wittwer , Stuttgart 1912.
  • Geodetic instruments. Booklet 4: Hammer-Fennels total station and topometer; Supplements to issue 1–3. Published by Konrad Wittwer , Stuttgart 1918.
  • Images and descriptions of some geodetic instruments. Published by Konrad Wittwer , Stuttgart 1912.
  • The Hammer-Fennel total station. Self-published, Kassel 1944.

literature

Web links

Individual evidence

  1. ↑ http://www.kassel.de/stadt/geschichte/chronik/info/09469/index.html
  2. ↑ Archived copy ( memento of the original from October 13, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.gih.uni-hannover.de
  3. ^ Artur Morpurgo: Fennel's new estimating microscope theodolites . In: Österreichische Zeitschrift für Vermessungswesen 1 (6), 1903, pp. 85–87. - Full text online (PDF; 3.96 MB) .
  4. ↑ https://theodolitbaugeschichte-2.jimdo.com/hauptteil-die-bauteile-des-theodolit-und-ihre-geschichte/mikrometer/strichmikoskop/
  5. ↑ https://theodolitbaugeschichte-2.jimdo.com/hauptteil-die-bauteile-des-theodolit-und-ihre-geschichte/mikrometer/nonienmikoskop/
  6. ↑ https://www.gih.uni-hannover.de/fileadmin/institut/pdf/instrument/theodolite.pdf p. 43f
  7. ^ FR Jung, G. Drees et al .: Bautechnik I (hut - pocket books of technology). Springer-Verlag , Berlin 1974, p. 16f.
  8. ↑ Hans Löschner: About total stations and their history. In: Österreichische Zeitschrift für Vermessungswesen 5 (7–8, 9–10, 11–12, 15–16, 17–18, 19–20, 21–22, 23–24), 1907. - Full text online (PDF; 22 MB) .
  9. ↑ https://www.spektrum.de/lexikon/geowwissenschaften/tachymeter/16228
  10. ^ Josef Mitter: The International Course for Geodetic Distance Measurement in Munich, September 1953. In: Österreichische Zeitschrift für Vermessungswesen 42 (2), 1954, S. 60. - Full text online (PDF; 1.78 MB) .
  11. ↑ Christoph Kleinn: Introduction to surveying for forest science students. Göttingen 2009, p. 39f .. - full text online (PDF; 3.1 MB) .
  12. ↑ https://www.deutsche-biographie.de/sfz15809.html
  13. ↑ Archived copy ( memento of the original from October 13, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.gih.uni-hannover.de
personal data
SURNAME Fennel, Adolf
BRIEF DESCRIPTION German industrialist
DATE OF BIRTH March 7, 1860
PLACE OF BIRTH kassel
DATE OF DEATH March 1, 1953
Place of death kassel