MAGNETIC COMPASS

The card immersed in liquid consist of distilled water and pure ethyl alcohol.

The mixture has following properties:-

• Low freezing point i.e about -30°C
• Small coefficient of expansion
• Does not discolor the card
• Low relative density i.e. about 0.93

• Doors giving access to the corrector magnets should always be kept closed.
• The soft iron spheres (Quadrantal correctors) and their bracket should be painted to prevent rust.
• If the binnacle is of wood, it should be varnished and not painted, as painting may cause doors to jam.
• Brass part of binnacle should be regularly polished.
• All magnetic materials and electrical wires should be kept as far as away from the compass.
• The helmet of binnacle should always be in place except where bearings are actually being taken. Cover it again after use.
• If bubbles may develop in the wet compass bowl, it has to be removed at the earliest possible time.