What is a Magnetic Compass, its principle, types and errors?

To see summary of magnetic compass Error, Click here.

Care and maintenance of magnetic compass:-

1. The doors giving access to the corrector magnets should always be kept locked and the keys kept is safe custody.
2. It the binnacle is of wood, it should be varnished not painted, as paint may cause the door to jam.
3. The soft iron spheres (quadrant correctors) and their brackets should be painted. This prevents rust.
4. The brass parts of the binnacle should be polished regularly.
5. All magnetic materials such as aerials stays, electrical machinery, electrical wires etc should be kept well away from the compass.
6. The helmet of the binnacle should be in position always except during the short periods when bearing are actually being taken.
7. The binnacle light should be switched off at daytime.
8. The wet compass card, if found defective owing to stickiness of movement has to be renewed by the manufacturer or his authorized agent. Here no spare wet card is carried. Instead an entire bowl is carried as a spare.
9. In pare cases a bubble may develop in the wet compass bowl. This has to be removed at the earliest opportunity.

How to Remove bubbles from magnetic compass :

A bubble may form in the bowl owing to the fact that some of the liquid has somehow escaped from the bowl. This is a bare occurrence and must be remedied by following the manufacturer’s instructions. In most compasses: