Click photos to enlarge.
"Kern AARAU SUISSE SWITZERLAND No 37845 DKM2"
height 8.25 inches
Heinrich Wild designed this DKM2 (a double circle theodolite with an optical
micrometer) for Kern in the 1930s. Like the T2 manufactured by Wild in Heerbrugg, the DKM2
is a light weight instrument with a steel frame. The horizontal and vertical circles are glass, and
read directly to single seconds. The telescope is equipped with stadia wires, and so can be used
for tachymetry. An auxiliary eyepiece lying alongside the telescope allows the user to read either
circle without moving away from the station. Here, however, the 2 scales are read through the
optical micrometer with reference to a centrally located index, giving the arithmetic mean of two
diametrically opposed points on the circle. In 1955, an instrument of this sort, with tripod, cost
$1,221. This instrument was purchased in 1963, and given to the Smithsonian in 1997.
Ref: Kern & Co., Ltd, Double Circle Theodolites (about 1959).