Humboldt State University

Robert A. Paselk Scientific Instrument Museum

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Engineer's Transit or Theodolite

Keuffel & Esser Co.

Humboldt S-T-C; c.1925

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The theodolite is a surveying instrument used for accurately measuring angles in both the vertical and horizontal planes using a telescope and graduated circles. The American transit is a slight variation in which the standards for the telescope are taller to enable the telescope to be completely revolved or transited in the vertical plane. The terms theodolite and transit are often used interchangably by American instrument firms and users.


An oval brass tag, attached with brass pins to the top of the mahogany case, is stamped: HUMBOLDT S-T-C / 557, the transit itself is engraved HSC 557.


Kiely, Edmond R. Surveying Instruments: Their History. Carben Surveying Reprints, Columbus (1979).

Smart, Charles E. The Makers of Surveying Instruments in America Since 1700. Regal Art Press, Troy (1962).


HSTC Instrument Collection

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HSTC (1921-34)
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HSC (1935-1953)
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HSC (1954-1973)

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© R. Paselk
Last modified 30 August 2010