Desilva Octant

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This octant has an ebony frame, reinforced brass index arm, and ivory name plate. The ivory scale is graduated every 20 minutes from -3° to +109°, and read by vernier with tangent screw to single minutes of arc. The inscription reads "W. DESILVA* LIVERPOOL."
The Smithsonian purchased this piece in 1903. At that time, it had a wooden box with a trade label that read "William Desilva, 78 Regent Road opposite the Bramley-Moore Hotel, Liverpool." Desilva was in business from 1851 to 1881, offering optical and nautical instruments.
Currently not on view
date made
mid 19th century
Desilva, William
place made
United Kingdom: England, Liverpool, Liverpool
Physical Description
ebony (frame material)
ivory (inlay material)
brass (overall material)
glass (overall material)
radius: 9 5/8 in; 24.4475 cm
overall: 12 in x 9 3/4 in x 3 3/8 in; 30.48 cm x 24.765 cm x 8.5725 cm
overall: 3 3/8 in x 9 7/8 in x 12 in; 8.5725 cm x 25.0825 cm x 30.48 cm
ID Number
catalog number
accession number
See more items in
Medicine and Science: Physical Sciences
Measuring & Mapping
Data Source
National Museum of American History


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