TERRESTRIAL MAGNETISM, ETC. 303 



The ends of this second wire are also united by 

 soldering or brazing, and thus an elastic ring is 

 produced strong enough to support the compass- 

 bowl. The compass-bowl is suspended from the 

 elastic ring with the intervention of a rigid gimbal 

 ring. The elastic ring has two sockets fixed at 

 the ends of a diameter, which rests on two balls 

 attached to the brass rim of the binnacle stand. 

 The elasticity of the ring mitigates the effect on 

 the knife-edges bearing the gimbal ring and bowl, 

 and on the point bearing the compass-card, of 

 vertical tremors of the platform on which the 

 binnacle rests. The knife-edges of the gimbal 

 ring are supported on two grooved stirrups, hung 

 by chains from the elastic rings. This suspension 

 mitigates the effect of horizontal tremors of the 

 platform. 



The most difficult and not the least interesting 

 part of my subject remains, the deviation of the 

 compass produced by magnetization of the ship 

 herself, or of iron in her fittings or cargo, and 

 practical appliances for relieving of these errors 

 the compasses of iron ships ; but limits of space 



