302 POPULAR LECTURES AND ADDRESSES. 



to India, China, and back by the West Indies, or 

 to Australia and New Zealand. 



To produce steadiness of the compass-card in 

 steamers which have powerful engines, and where 

 there is much vibration, it has been customary 

 to suspend the bowl by means of india-rubber 

 bands. A serious objection to this method is that 

 the india-rubber is liable to become rotten by ex- 

 posure to heat or oil, especially if it is used in fine 

 enough bands to give the requisite steadiness in all 

 circumstances. After many trials of metallic springs 

 in lieu of india-rubber, I at last found a plan of 

 brass spring resembling a rope grummet, but with 

 clastic brass wire instead of the rope strands, by 

 which I succeeded in obtaining more satisfactory 

 steadiness of the compass than with india- 

 rubber. The construction of this brass grummet- 

 ring and the mounting of the compass-bowl upon 

 it, may be described as follows : A single wire is 

 first bent and its ends are united by soldering 

 or brazing, so as to form a ring of the proper size. 

 This serves as a core on which a second brass 

 wire is laid on spirally, six turns round the core. 



