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Dry compass
Card-Mica covered with paper, white with black markings, graduated to 1/4 points. At centre of card is hole 1" dia. to accommodate pivot.
Needle-Four edge bar needles of laminated steel, each having two laminations. 2 x 3.75" and 2 x 2.75" long, and 0.4" deep. All mounted 1" apart. Attached to a metal ring 2.75" dia. which is screwed to card.
Pivot- Inverted type (missing), the brass knee pieces for securing gimbal ring to inner needles, are in place. A light gun metal bell-shaped weight 1.25" is attached to centre of card below pivot gimbal position, by two thumb screws.
Needle-Four edge bar needles of laminated steel, each having two laminations. 2 x 3.75" and 2 x 2.75" long, and 0.4" deep. All mounted 1" apart. Attached to a metal ring 2.75" dia. which is screwed to card.
Pivot- Inverted type (missing), the brass knee pieces for securing gimbal ring to inner needles, are in place. A light gun metal bell-shaped weight 1.25" is attached to centre of card below pivot gimbal position, by two thumb screws.
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Object Details
| ID: | ACO0956 |
|---|---|
| Type: | Dry compass |
| Display location: | Not on display |
| Creator: | Preston, Grant |
| Date made: | 1837-1840; 1837-40 |
| Credit: | National Maritime Museum, Greenwich, London, Admiralty Compass Observatory |
| Measurements: | Overall: 25 mm; Diameter: 97 mm |