True North is at the centre of the north pole This is a fixed point at the top of the planet. The majority of our navigational charts are orientated so that they use true north as their reference point. This is because true north doesn’t move. Magnets don’t point towards true north however. They point toward magnetic north which is in a different geographical place. The difference in the angle between true north and magnetic north is call variation.Three wooden boxes containing magnetic compass quadrantal correctors, correcting magnets and shadow pins.Saura Keiki Seisakusho Co Ltdcompass, correcting magnets, magnetic variation

A ship is said to heel when it leans over to one side. A heeling instrument corrects an error on the ships magnetic compass caused by this lean or heel unless the compass had been stabilized and corrected with small magnets to prevent such errors. Instrument for measuring ships heeling error, in wooden boxNo. 0.408heeling, heeling error, compass, marine instruments