J. White Dry Card Compass with Binnacle

Description
This is the model that accompanied William Thomson's 1880 application for an American patent for an improved mariner’s compass. The U.S. Patent Office transferred it to the Smithsonian in 1926. This compass has eight short magnetic needles suspended by threads. The card is relatively large, but its central part is cut away. The binnacle has large iron balls designed to compensate for the magnetism of the ship itself. Thomson claimed that his design offered five advantages: greater steadiness of the compass card and diminished wear of the bearings; greater steadiness of the compass in vessels of war during gun-fire; improved method of applying correctors for the semicircular error; improved auxiliary instruments to correct the heeling error; and improved compass card. The inscription reads "SIR WM THOMSON’S PATENT. J. WHITE, MAKER GLASGOW."
Ref: W. Thomson, "Mariner's Compass," U.S. Patent #232,718.
Location
Currently not on view
Object Name
dry card compass
date made
1880
maker
J. White
Measurements
overall: 30.5 cm x 18.5 cm x 15.5 cm; 12 in x 7 5/16 in x 6 1/8 in
place made
United Kingdom: Scotland, Glasgow
ID Number
PH*308557
accession number
89797
catalog number
308557
patent number
232,781
subject
Measuring & Mapping
Navigation
See more items in
Medicine and Science: Physical Sciences
Navigation
Data Source
National Museum of American History, Kenneth E. Behring Center

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