Wild Subtense Bar

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.
Currently not on view
Wild, Heinrich
overall: 2 m; 6 9/16 ft
ID Number
accession number
catalog number
See more items in
Medicine and Science: Physical Sciences
Measuring & Mapping
Surveying and Geodesy
Data Source
National Museum of American History