Smithsonian - National Museum of American History, Behring Center

Physical Sciences Collection - Surveying and Geodesy

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Locke Level (binocular) - click to enlarge

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Locke Level (binocular)

Catalogue number:

"W. & L. E. GURLEY TROY N. Y."

30125 cm long


In 1886 William Gurley (1821-1887) obtained a patent (#353,406) for a Locke level with the vial inside the telescope tube. He described it as "a short, compact, cheap, durable, efficient, easily adjustable, and well-incased telescopic leveling-instrument, having a very large and clear field, and requiring but one eye to be used by an engineer or surveyor in quickly taking preliminary or approximate levels with the instrument held by hand." Maria Gurley, William's wife and executrix of his estate, obtained a patent (#360,805) for a binocular version of this instrument in 1887. Here the tube on the right holds the usual lenses of an opera glass, while the tube on the left holds the level vial, prism, and cross wires of the level. The monocular was soon selling for $12, and the binocular for $15, and both remained on the market for about 30 years. The Interstate Commerce Commission transferred this instrument to the Smithsonian in 1962.

Ref: W. & L. E. Gurley, A Manual of the Principal Instruments Used in American Engineering and Surveying (Troy, N.Y., 1893), pp. 225-226.

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