Smithsonian - National Museum of American History, Behring Center

Physical Sciences Collection - Surveying and Geodesy

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Heliotrope (telescopic) - click to enlarge

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Heliotrope (telescopic)

Catalogue number:

"FAUTH & CO. WASHN D.C." and "U.S.G.S. No 6"


This instrument consists of a refracting telescope surmounted by a round mirror that can reflect a beam of light along the optical axis of the telescope. A screw base allows it to be attached to any tree or post. Fauth advertised a heliostat of this sort in 1877, describing it "As made by us for the United States Coast Survey." This example was made before 1887 when G. N. Saegmuller began putting serial numbers on Fauth instruments. New, it cost $30. The United States Geological Survey was established in 1879, and transferred this instrument to the Smithsonian in 1907.

Ref: Fauth, Catalogue of Astronomical and Surveying Instruments (Washington, D.C., 1877), p. 43.

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