196 THE INTELLECTUAL RISE IN ELECTRICITY. 



The knowledge which Columbus had of the compass 

 and of the magnet, therefore, rested on both practical and 

 theoretical grounds. Of the compass, his early voyages 

 had taught him even more than the ordinary use. In a 

 letter to Ferdinand and Isabella, dated 1495, he describes 

 how, having been sent by King Rene to Tunis to capture 

 a galley, he found, on arriving at the island of San Pedro, 

 in Sardinia, so powerful a force arrayed to meet him that 

 his crew became alarmed and insisted on returning to 

 Marseilles for reinforcements, u upon which," he con- 

 tinues, "being unable to force their inclination, I yielded 

 to their wish, and, having first changed the points of the 

 compass, spread all sail, for it was evening, and at day- 

 break we were within the Cape of Carthagina, while all 

 believed, for a certainty, they were going to Marseilles." 1 



This is of a piece with his alteration of the reckoning 

 of the ship's progress during his first voyage to the New 

 World. It not only shows his familiarity with the com- 

 pass, but incidentally furnishes an instance of that very 

 tampering with the instrument against which the severe 

 provision already noted in the Laws of Wisbuy was di- 

 rected. 



If Columbus was not familiar with Roger Bacon's work, 

 he at least had learned, somehow, of the theory of the 

 magnet, in which both Bacon and Peregrinus believed ; 

 namely, that the magnet was not controlled by the North 

 star, but by all points of the heavens ; for, in the history 

 written by his son, he is expressly credited with this idea. 



The figure of the great Admiral is one of especial inter- 

 est in this research, because of the remarkable magnetic 

 discoveries which he made. As this subject appears to 

 have been confused by certain of his biographers, seme 

 detailed consideration of it is necessary. 



A geographical meridian of the earth passes, as we 

 know, through any given point of observation and the 

 earth's geographical poles. The compass needle may 



1 Major: Select Letters, cit. sup., p. xxxvi. 



