Second half 20th century theodolite  


Second half 20th century Askania Tu400 theodolite
Instrument:Theodolite type Tu 400
Manufacturer:Askania
Country of origin:Germany
Manufacturing year:Second half 20th century

I was given this theodolite in 2008 by a former colleague as one of several land surveying instruments and accessories. The instrument was manufactured by Askania (nowadays known for their wrist watches).

Askania's history begins in 1871, when the inventor Carl Bamberg, a protégée of Carl Zeiss and son of a horologist, establishes the roots of Askania in Berlin and manufactures precision instruments for navies, observatories, research and expeditions.[1][2] The actual firm 'Askania Werke AG' was established in 1921.[3] In 1971 Askania was taken over by Siemens.2 In 2006 Askania was re-established, now producing quality mechanical wrist-watches after classical designs.[2] They feature the same logo as the original firm.[1]

The link with Carl Zeiss is obvious as the base of the Zeiss Th42 is interchangeable with the Askania tribrach thanks to their DIN 18719 stub and socket joint (see fig. 4). The carrying dome shows similarities to the ones used by Wild Heerbrugg, although the one from Askania is considerably wider at 190mm outer diameter (measured halfway up the dome).

According to a 1957 Askania brochure the Tu400 was meant for triangulation, traversing and field astronomy (see fig. 11)).[4] In 1967 a degree version of the the Askania Tu400 was listed as the K&E KE-2(e) 'One-Second Theodolite' in the Keuffel and Esser (K&E) catalogue (see fig. 12).[4] That both instruments are the same is confirmed by Deumlich in his Instrumentenkunde der Vermessungstechniek (1972), p. 134. On the instrument in my collection both the horizontal and vertical circles are divided in gon (400 divisions in a full circle) and - as indicated in the catalogue and brochure - can be read down to 0.0002gon (about 1 arc second, see fig. 5) and estimated one further decimal. The instrument has a pendulum type compensator for the vertical scale.

I am looking for further information of this instrument:

If you can answer any of these questions, please let me know.

[1]: History page Askania web site
[2]: Askania Werke AG page on German Wikipedia site (with thanks to Jürgen Hoefeld for pointing me to this page).
[3]: French c1931 Askania brochure and catalogue (with thanks to John Vossepoel for pointing me to this site).
[4]: Many thanks to John Vossepoel for sending me these pages.