PREVIOUS CRUISES OF THE CARNEGIE AND 

 PURPOSES OF CRUISE VII 



The history of the Carnegie has been so closely bound up with 

 recent developments in magnetism, that it will be justifiable to 

 recite briefly some of the salient facts of this science. The story 

 begins, of course, with the introduction of the compass for navi- 

 gation, some hundred years before the voyages of Columbus. 

 He was the first, however, to note that the compass does not 

 point to true north except at a few points on the Earth. 



This bewildering behavior of the trusted instrument more than 

 once got him into difficulties. On his first passage to America, 

 the crew was greatly disturbed, and on the point of mutiny, when 

 they saw the needle point ten degrees west of true north. They 

 did not wish to trust the compass any longer, for fear they should 

 never find their way home. Columbus allayed their fears by 

 saying that the officers must have made some mistake in the 

 bearings of the Pole Star, and that in the morning he would in- 

 vestigate. 



Sure enough, when morning came the compass was seen to 

 read correctly again. The wily Columbus had no doubt shifted 

 the compass-card under the needle, as he admitted having done 

 on a previous expedition. He writes: "Being unable to force 

 the crew's inclination, I yielded to their wish, and, having first 

 changed the points of the compass, spread all sail, for it was 

 evening; and at daybreak we were within the Cape of Carthagena 

 while all believed for a certainty that they were going to Mar- 

 seilles." 



In doing this Columbus was taking chances, for laws had been 

 framed against falsifying the compass. In one of these curious 

 statutes, mariners were charged not to eat onions or garlic, lest 

 the odor "deprive the lodestone of its virtue by weakening it and 

 prevent them from perceiving their correct course." The pun- 

 ishment for violations seem barbarous in the extreme, for the 



