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Alidade
This instrument consists of a diameter cut away and two folding sight vanes. The diameter has a crossbar at centre which holds a raised section to accommodate the compass spigot. The back sight vane is a wide slit with a V notch at the top. It has two spring clips. The fore sight is an open arch and thread,(missing). There is a raised point at the top of the vane. The thread also runs along the diameter. Both vanes can be locked upright by small levers.
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Object Details
| ID: | ACO0714 |
|---|---|
| Type: | Alidade |
| Display location: | Not on display |
| Creator: | Unknown |
| Date made: | 1870 ? |
| Credit: | National Maritime Museum, Greenwich, London, Admiralty Compass Observatory |
| Measurements: | Overall: 143 mm x 195 mm x 28 mm |
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