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Dry compass
Card-Mica covered with paper,white with black markings, graduated to 1/4 points, has decorated East point. At centre of card is a hole 1.25" dia. to accommodate pivot.
Needle- Four solid edge bar needles 2 x 4" and 2 x 3" long and 0.5" deep, the inner needles are 1.3" apart, outer needles 0.6" outside inner ones. Attached to a metal ring 3.75" dia. which is screwed to card.
Pivot-Inverted pivot carried in double brass gimbals mounted through hole at centre of card, and secured to underside of card and the two inner needles by brass knee pieces and clamp. A very heavy brass bell-shaped weight 1.75" dia. is attached to centre of card below pivot gimbals, by brass knee pieces attached to gimbal mountings.
Needle- Four solid edge bar needles 2 x 4" and 2 x 3" long and 0.5" deep, the inner needles are 1.3" apart, outer needles 0.6" outside inner ones. Attached to a metal ring 3.75" dia. which is screwed to card.
Pivot-Inverted pivot carried in double brass gimbals mounted through hole at centre of card, and secured to underside of card and the two inner needles by brass knee pieces and clamp. A very heavy brass bell-shaped weight 1.75" dia. is attached to centre of card below pivot gimbals, by brass knee pieces attached to gimbal mountings.
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Object Details
| ID: | ACO0952 |
|---|---|
| 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: 40 mm; Diameter: 105 mm |