000-100-104-301-C
© National Museums Scotland |
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Octant
An octant is a navigational instrument used for measuring angles necessary for determining a ship's position at sea. This wooden example was made around 1760, probably by John Urings, a ship-chandler based in London's Fenchurch Street between 1735 and 1771.
The 16-inch radius mahogany-frame octant has a foresight and backsight with brass fitments. There is an ivory plate stamped 'I. URINGS. Fecit. LONDON.' The inset boxwood scale is divided to 20 minutes, and by transversals to 2 minutes of arc.
An octant is so-called because the scale is one-eighth of a circle, although it can measure 90 degrees using the mirror on the top of the radial arm.
Record details
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| Online ID: |
000-100-104-301-C |
| Image Rights Holder: |
National Museums Scotland |
| Project: |
0098: National Museums Scotland
Project description | View all records in project |
| Ref: |
National Museums Scotland T.1987.150 |
| Date: |
Around 1760
c. 1760
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| Material: |
Mahogany, brass, ivory. Inscription: I. URINGS. Fecit. LONDON.
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| Dimensions: |
470 mm x 390 mm x 90 mm
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| What: |
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| Subject: |
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| Who: |
John Urings, London (Maker)
The Leith Nautical College Collection
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| Where: |
England, London
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| Event: |
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| Description: |
Sixteen inch octant with foresight and backsight in mahogany with brass fitments, made by John Urings of London about 1760
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| References: |
- For a description of the octant and its use, see Turner, G. L'E. Antique Scientific Instruments. Poole: 1980. p 34; Bennett, J.A. The Divided Circle: A history of instruments for astronomy, navigation and surveying. Oxford: 1987. p 132-4
- For Urings, see Clifton, Gloria, Directory of British Scientific Instrument Makers 1550-1851. London: 1995, p 285
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