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Liquid Compass - click to enlarge

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Liquid Compass

Catalogue number:

"E. S. RITCHIE BOSTON. PATENTED SEPT. 9, 1862. APL. 7, 1863. MAY 12, 1868. July 19, 1870" and "6937" and "U.S.C.&G.S."

card 6.5 inches diameter; bowl 7.5 inches diameter

This compass–with six needles, and a flat card with central buoyancy–was Ritchie’s most successful design and was widely used by American merchant ships and the U.S. Navy. The Ritchie ledgers, now held by Ritchie Navigation, indicate that this example was manufactured on Jan. 5, 1873 and sold to one L. J. Sloane. The U.S. Coast & Geodetic Survey acquired it in 1914, and transferred it to the Smithsonian in 1929.

Ritchie’s patent of Sept. 9, 1862 (#36,422) described a liquid compass so designed that the liquid would not oxidize the magnet or card, and that the friction and wear of the pivot and its bearing was minimized. Ritchie obtained two patents on April 7, 1863. One (#38,125) described a needle enclosed in an air-tight metallic case; the other (#38,126) described a liquid compass that could be read at a distance so it would not be affected by any iron on or about the deck of a ship. Ritchie’s patent of May 12, 1868 (#77,763) described a paint that would not deteriorate in the liquid in the compass. His patent of July 19, 1870 (#105,492) described a way to hold the glass in place with a water-tight joint.

Ref: E. S. Ritchie & Sons, Ritchie’s Liquid Compasses and Nautical Instruments (ca. 1905).

T. S. & J. D. Negus, Illustrated Catalogue of Nautical Instruments (New York, n.d.), p. 204.

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