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Spider card - aircraft compass
Type O.2, spider card
Card: Mica ring dia. 2.0" (5.1cm) supported on eight elements which are bent downwards at edge of card and are then bent upwards at their extreme ends. Float dome at centre of spider incorporates an inverted pivot spike on its lower surface.
Needle: Two needle magnets are attached below card. A ring is attached between magnets which engages on a flange on pivot stem, to prevent card from lifting off pivot.
Pivot: Brass stem having a pivot cup at top and flange on which ring below card engages.
Mounted on wooden base.
Card: Mica ring dia. 2.0" (5.1cm) supported on eight elements which are bent downwards at edge of card and are then bent upwards at their extreme ends. Float dome at centre of spider incorporates an inverted pivot spike on its lower surface.
Needle: Two needle magnets are attached below card. A ring is attached between magnets which engages on a flange on pivot stem, to prevent card from lifting off pivot.
Pivot: Brass stem having a pivot cup at top and flange on which ring below card engages.
Mounted on wooden base.
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Object Details
| ID: | ACO0359 |
|---|---|
| Type: | Spider card - aircraft compass |
| Display location: | Not on display |
| Creator: | Unknown |
| Date made: | 1924 |
| Credit: | National Maritime Museum, Greenwich, London, Admiralty Compass Observatory |
| Measurements: | Overall: 55 mm; Diameter: 85 mm |