Accession No
2762
Brief Description
theodolite or miner's dial, by Hilderbrand, Fruher, August Lingke & Co., Germany, c. 1920
Origin
Germany; Freiberg
Maker
Hiderbrand Fruher August Lingke & Co.
Class
surveying
Earliest Date
1920
Latest Date
1920
Inscription Date
Material
metal (brass, steel, one other); glass; wood
Dimensions
box height 395mm; breadth 285mm; depth 315mm; height 270mm; horizontal circle diameter 134mm; vertical circle diameter 115mm
Special Collection
Provenance
Transferred from Sedgwick Musuem, Department of Earth Sciences, University of Cambridge, Cambridge, England, 09/1981.
Inscription
‘HILDERBRAND
FRUHER
AUGUST LINGKE & CO
FREIBERG IN SACHSEN’ (on horizontal circle)
‘M/7’ (on horizontal circle)
‘No 1960’ (on horizontal circle)
Description Notes
Brass telescope, screws, vertical circle and compass box; metal alloy mounts; horizontal circle finished in mottled green varnish. Enclosed horizontal circle with silvered scale divided 0 - 360 numbered by 1 subdivided to 20´; read by vernier to 1´ with 2 opposing reading miscroscopes and white reflector. Clamp and slow motions screws for horizontal circle. ‘U’ shaped frame supports telescope, axis and vertical circle; clipping screws; rack and pinion focussing eyepiece; cross hairs; clamp and slow motion screws. Vertical circle with silvered rim divided 60 - 0 - 60 numbered by 10 subdivided to 1. (Glazed civer missing). Blued steel needle wrapped separately. Bubble mounted on telescope and second on ‘U’ frame. Tribrarch limbs with levelling feet. Fitted wooden box (not original ?)
Condition
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:44123
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