Abstract
It is known that the steadieness of magnetic compass are disturbed by rolling of the vessel. The damping period of magnetic compass card has been occasionally synchronised with the period of rolling of the vessel. We have found that damping curve of magnetic compass card has been related with the period, viscosity or temperature of the liquid, diameter of the card, magnetic moment of the compass, and horizontal magnetic force on the earth. On account of above reason ; if we know some elements, we can easily find out one of the rest. This experiments should be coutributed to konw the condition of magnetic field in the vessel and to determine the dimension of the magnetic compass which is newly designed by the requirement of ship owner.
