286 POPULAR LECTURES AND ADDRESSES. 



the diameter of the circle ; and this is still a 

 favourite size of compass in large merchant ships. 

 Compasses have been made as large as fourteen or 

 fifteen inches, and as small as four or five inches 

 for use on board sea-going ships. The Admiralty 

 standard compass is only seven and a half inches 

 in diameter, 1 and the steering compasses in the 

 British Navy are generally still smaller. The 

 practical experience of merchant sailors has led 

 them to prefer larger sizes. Some of the great 

 ocean steam navigation companies, after trying the 

 Admiralty standard compass, and then the other 

 extreme of fifteen-inch compasses, fell back upon 

 ten inches. This is the size most commonly now 

 in use for standard and azimuth compasses in 

 preference to Gilbert's old size of twelve inches. 

 Sailors naturally like the larger compass because 

 it is more easily read at a distance, which, at all 

 events for a steering compass, is a real practical 

 advantage. Still, if the smaller compass worked 



1 [Note added June, 1890.] This was the case from about 1840 

 till the end of 1889, when my ten-inch compass described below 

 was adopted as the Admiralty standard compass. 



