Accession No

5195

Brief Description

theodolite, by August Lingke & Co., Germany, c. 1880

Origin

Germany; Freiberg

Maker

August Lingke & Co.

Class

surveying

Earliest Date

1870

Latest Date

1890

Inscription Date

Material

metal (brass, silver); plastic; glass

Dimensions

height 267 mm; length 280 mm; width 234 mm

Special Collection

Provenance

Donated in 08/12/1997. From the estate of G. Ellwood, Harlow, Essex.

Inscription

‘AUGUST LINGKE &CO.
FREIBERG IN SA:’ (ENGRAVED ON BASE PLATE)

Description Notes

Tripod base, knurled adjustable feet each engraved with ‘M’ ‘3’ and an anchor, plastic protectors for feet to stand on. Knurled knobs for coarse and fine azimuthal adjustment, circular base plate calibrated 0-(360)° by 10 on brass, divided by 1 to 10 minutes on silver strip, occasionally tarnished to illegibility. Stand for ¿artificial horizon (missing). The reading microscopes mounted diametrically opposite each other labelled ‘A’ and ‘B’ respectively, calibrated to 20 seconds of arc (each minute is divided (0)-(30) by 10) fixed focus, plastic lens caps. Reversible telescope, coarse and fine altitude adjust (no calibration) pin hole and cross hairs sight, lense caps coarse focus knob cross hairs, missing objective lens. Pages from a 1989 diary mentioning it.

References

Events

Description
The Theodolite is a relatively, simple tool used for measuring angles, both horizontal and vertical. They work using the same principles as a protractor, the ‘point A’ is located and the angle noted, and then the telescope is pointed at ‘point B’ and the second angle is taken.

Although primarily used in surveying the theodolite can be applied to both Meteorology and Navigation.

Gemma Frisius proposed the idea behind the theodolite in 1533. At the time new methods of surveying were being used and by combining an Alidade, a magnetic compass and the degree scale on the back of an Astrolabe, the calculations made by modern theodolites could be observed. Unfortunately, this method was not practical due to the combination of instruments. The best of the attempts to simplify the process was the ‘theodolitus’, first described in print by Leonard Digges in 1571.

However, this instrument could only take measurements in the horizontal plane. Despite this it was still thought of as the ‘common’ Theodolite up to the late 18th century.

During the 19th century the Altazimuth Theodolite was considered the most useful theodolite, as it could measure on the horizontal and vertical planes. Three notable types of Altazimuth Theodolite were developed: The Everest Theodolite, the Plain Theodolite and the Transit Theodolite. It is the Transit Theodolite, which is still used today.

FM:43270