288 POPULAR LECTURES AND ADDRESSES. 



the Admiralty " J " card, provided for use in stormy 

 weather) there is a swelling in the middle of each 

 of the steel needles to make them heavier ; in 

 others heavy brass weights are attached to the 

 compass cards as near the centre as may be, being 

 sometimes, for instance, in the form of a small 

 brass ring of about an inch and a half diameter. 

 Another method, scarcely less scientific, is to blunt 

 the bearing-point by grinding it or striking it with 

 a hammer, as has not un frequently been done to 

 render the compass " less lively ; " or to fill the cup 

 with brickdust, as is reported by the Liverpool 

 Compass Committee to have been once done 

 at sea by a captain who was surprised to find 

 afterwards that his compass could not be trusted 

 within a couple of points. All these methods 

 are founded on the idea that friction on the 

 bearing-point is the cure for unsteadiness. In 

 reality friction introduces a peculiar unsteadiness 

 of a very serious kind, and is very ineffective 

 in remedying the proper unsteadiness of which 

 something is essential and inevitable in a com- 

 pass on board a ship rolling in a heavy sea, and 



