Condy Octant
- Description
- An octant measures angles by bringing two images together—that of the sun, for instance, and the horizon—and was used primarily to determine latitude at sea. The form was described by John Hadley in London in 1731 and still in use in the early twentieth century.
- This example is marked "B. CONDY PHILADELPHIA 1778," the signature being that of Benjamin Condy (d. 1798). It was made during the American Revolution, and there are faint markings on the scale that may read "equality" and "justice." It has a mahogany frame and index arm, and ivory inset. The boxwood scale is graduated every 20 minutes from -5° to +95° and read by ivory vernier to single minutes of arc. There is also a back sight and a back horizon mirror for measuring angles greater than 90°. The radius is 17.75 inches.
- Location
- Currently not on view
- Object Name
- octant
- Date made
- 1778
- business owner
- Condy, Benjamin
- maker
- Condy, Benjamin
- Physical Description
- wood (overall material)
- brass (overall material)
- glass (overall material)
- Measurements
- average spatial: 7.9 cm x 42.1 cm x 51.8 cm; 3 1/8 in x 16 9/16 in x 20 3/8 in
- Place Made
- United States: Pennsylvania, Philadelphia
- ID Number
- 1992.0312.01
- catalog number
- 1992.0312.01
- accession number
- 1992.0312
- catalog number
- 92.312.1
- subject
- Measuring & Mapping
- See more items in
- Medicine and Science: Physical Sciences
- Data Source
- National Museum of American History, Kenneth E. Behring Center
- Additional Media
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