Wild Subtense Bar

Description
A subtense bar is a bar of known length, with targets at either end. It is usually made of a stable material such as invar (an iron-nickel alloy). When used with a theodolite, it serves as a quick and convenient method of measuring distances indirectly. The subtense technique is similar to that involving a tachymeter and graduated rod. Subtense bars were in use in Europe by 1930. This example is marked "WILD HEERBRUGG SWITZERLAND No. 86845."
Ref: Wild Heerbrugg, Wild GBL 2m Subtense Bar (Heerbrugg, 1972).
F. Ackerl, "Entfernungsmessungen mit der Wildschen Invar-Basislatte," Zeitschrift für Instrumentenkunde 9 (1932): 393-400.
Location
Currently not on view
Object Name
subtense bar
maker
Wild, Heinrich
Measurements
overall: 2 m; 6 9/16 ft
ID Number
1996.0186.02
accession number
1996.0186
catalog number
1996.0186.02
See more items in
Medicine and Science: Physical Sciences
Measuring & Mapping
Surveying and Geodesy
Data Source
National Museum of American History, Kenneth E. Behring Center

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