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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 a hole 1" dia. to accommodate pivot.
Needle- Three edge bar needles (fourth missing) 2 x 3.75" and 1 x 2.75" long. Composed of laminated steel. Outer needle 0.25" deep with two laminations, inner needles 0.25" deep at ends having semi-circular swell at centre 1.25" dep, with four lamianations. The needles are 1" apart. Attached to a metal ring 3.25" dia. which is screwed to card.
Pivot-Inverted type (missing), two brass knee pieces for securing gimbal ring to inner needles, are in place.
Needle- Three edge bar needles (fourth missing) 2 x 3.75" and 1 x 2.75" long. Composed of laminated steel. Outer needle 0.25" deep with two laminations, inner needles 0.25" deep at ends having semi-circular swell at centre 1.25" dep, with four lamianations. The needles are 1" apart. Attached to a metal ring 3.25" dia. which is screwed to card.
Pivot-Inverted type (missing), two brass knee pieces for securing gimbal ring to inner needles, are in place.
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Object Details
| ID: | ACO0955 |
|---|---|
| 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: 32 mm; Diameter: 100 mm |