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Compass deflector
Iron and Brass.
Kelvin's adjustable deflector for completely determining the compass error when sights of heavenly bodies, or compass marks on shore, are not avainable, as for example in fog or on a cloudy night.
Height: 3" (7.6 cm)
A deflector patented (No. 4876) by Sir Wm Thomson in 1876. This consists of two pairs of magnets mounted on a framework and pivoted so as to be capable of having their opposite poles closed in on each other or opened out, by means of a right- and left-handed screw operating in two sockets.
The deflector is used for measuring the horizontal direction magnetic force on board ship, as the ship’s head is turned in different directions, and from these observations to ascertain by the proper application of the appropriate formulae, the semi-circular and quadrantal errors.
Kelvin's adjustable deflector for completely determining the compass error when sights of heavenly bodies, or compass marks on shore, are not avainable, as for example in fog or on a cloudy night.
Height: 3" (7.6 cm)
A deflector patented (No. 4876) by Sir Wm Thomson in 1876. This consists of two pairs of magnets mounted on a framework and pivoted so as to be capable of having their opposite poles closed in on each other or opened out, by means of a right- and left-handed screw operating in two sockets.
The deflector is used for measuring the horizontal direction magnetic force on board ship, as the ship’s head is turned in different directions, and from these observations to ascertain by the proper application of the appropriate formulae, the semi-circular and quadrantal errors.
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Object Details
| ID: | NAV0252 |
|---|---|
| Type: | Compass deflector |
| Display location: | Not on display |
| Creator: | Thomson, William |
| Date made: | circa 1876 |
| People: | Nelson, M. H. H. |
| Credit: | National Maritime Museum, Greenwich, London |
| Measurements: | Overall: 80 mm x 160 mm x 58 mm |
| Parts: | Compass deflector |