1966 Kern DKM2This theodolite arrived in my collection in 2015. It came from the collection of the land surveying department of the Hogeschool van Utrecht, but is now on long term loan in my collection. Previously a Kern E1 electronic theodolite entered the collection.
When Heinrich Wild left Wild Heerbrugg he joined Kern Aarau where he continued designing theodolites. The Kern DKM2 was meant to be the competitor of the Wild T2 and thus has similar specifications. The DKM2 shows features well known from Wild's original designs while working in Heerbrugg, but at the same time this instrument shows that his ideas kept on evolving while working at Kern in Aarau.
Old design features known from the Zeiss Th1 and archetype Wild T2 include:
The characters "DK" in DKM2 indicate that this is a Doppelkreis (double-circle) theodolite.2 Doppelkreis instruments are equipped with double graduated circles (see figure 15), where the surface on the inside of the circle is graduated coarsely and finely on the outside. By superimposing them on top of each other the former serves as a visual reference for the latter.
The character "M" in DKM2 indicates that this model is equipped with a micrometer.3 Like the Wild T2 the micrometer can be viewed through the micrometer reading telescope next to the main telescope of the instrument.
The specimen showed here has centesimally divided circles. The diameter of them is 70 millimetres for the vertical circle and 75 millimetres for the horizontal one. They can be read directly to 2cc (0.0002 gon or 1" for the sexagesimal version) and estimated to 1cc (0.0001gon or 0.1" for the sexagesimal version).
The telescope has a 30 times magnification and a 45 millimetres diameter objective. It produces an inverted view. By default the DKM2 was equipped with single lines for both the vertical and horizontal cross-hairs. Customers could choose from eight different types of reticles, the specimen shown here has model G etching (the Zeiss Th1 type of reticle).5
The vials have an accuracy of 20" per 2 millimetres run. The one for the vertical circle is equipped with a coincidence reading system as may be expected from an instrument designed by Heinrich Wild.
The instrument weighs 3.6 kilograms, with an additional 1.8 kilograms for the container.
This particular DKM2 once belonged to the Hogeschool Utrecht where it served educational purposes. Thanks to that it is in pristine condition. It came complete with its original container in which the the tools are still present (see figure 3, figure 9 and figure 10).
Notes: Kern Aarau, 'Doppelkreis-Theodolite', in: Kern & Co. Ag. Aarau, Schweiz: Prospekt DK 562, (Aarau, before 1964), pp.2-6.
: idem, p.2.
: idem, p.3.
: idem, p.7.
: idem, p.33.
If you have any questions and/or remarks please let me know.
19th C. SDL 1919 K&E 1926 Zeiss RThII 1924 Zeiss Th1 1929 Wild T2 1937 Wild T3 (astronomic) 1939 Wild T3 (geodetic) 1943 CT&S Tavistock 1948 Wild T1 1952 Wild RDH 1956 Wild T0 1961 Wild T1A 1961 Wild MIL-ABLE T2 1962 Wild T2 1963/76 Wild T2 - DI3S 1963 Wild RDS 1966 Kern DKM2 1969 Wild T2E 1976/79 Wild T2 mod - DI4 1990 Wild T2 mod - Di1000 20th c. Askania Tu400