Binnacle, HMCS Swansea
Binnacles, like this example from the Canadian frigate HMCS Swansea, house a magnetic compass and were essential in ensuring that ships stayed on course and could accurately determine their position at sea.
A brass hood (top) protects the compass, which is lit by a small light. The use of non-magnetic materials like brass and wood reduces interference with the magnetic compass, while two compensating magnets (left and right) offset the effects of the steel and iron used in the ship. Lower on the housing, a clinometer (centre) measures the list or roll of the ship from side to side.
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