Accession No

4477

Brief Description

instructional theodolite, by Stanley, English, 20th Century

Origin

England; London

Maker

Stanley

Class

surveying

Earliest Date

1900

Latest Date

1970

Inscription Date

Material

metal; brass; steel; glass; wood

Dimensions

height 360mm

Special Collection

Provenance

Gifted by the Department of Geography, University of Cambridge, on 29/06/1994.

Inscription

‘STANLEY LONDON
MADE IN ENGLAND
RD. 878600 (UK) RD. 84198 (INDIA)
RD. 1257 (CEYLON) RD. 482 (PAK)
SERIAL NO 62123’ (horizontal circle)
‘STANLEY
INSTRUCTIONAL
THEODOLITE’ (box)

Description Notes

Horizontal circle set on tripod stand with adjustment screws acting as feet. Circle divided [0] - 360˚, numbered by 10˚, graduated to 1˚. Mounted above this is the compass (with degree circle divided 0 - [360˚], numbered by 90˚, graduated to 5˚) and one bubble level. U-shaped bracket within which the telescope is mounted. One side of the bracket another bubble level can be mounted. Telescope apparatus consists of telescope, vertical circle (divided 0 - 90˚ - 0 - 90˚ - 0, numbered by 10˚, graduated to 1˚) and bubble level. Telescope has no optics and a hand operated diaphragm. It can swivel in a trunnion axis which tilts without disturbing vertical axis.
Telescope and second bubble level are stored separately in the box.
Mahogany box with brass hinges and fasteners, and leather carrying strap.

Condition; fine; complete

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:40474