THE MAGNETIC ROCKS. 203 



tical matters, and knew less, were more interested in 

 speculating upon it and evolving new causes. Despite the 

 light shed upon the problems of navigation by Prince 

 Henry and his wise men, the myth of the magnetic rocks 

 still survived among sailors the world over. With the 

 discovery of variation, this assumed new vigor. Here was 

 an explanation of the aberration of the needle ready at 

 hand, and it was promptly and universally adopted. When 

 the chart of the New Continent was added to the Edition 

 of 1508 of Ptolemy's geography, the magnetic rocks, hav- 

 ing traversed the Indian Ocean and the Mediterranean, at 

 last came to final anchorage north of Greenland, which 

 was depicted as the eastern part of Asia, and the earth 

 was given a magnetic pole in the shape of an insular 

 mountain. 1 



The idea of a magnetic pole of the earth governing the 

 compass, to which Peregrinus alludes but dismisses be- 

 cause of the wide distribution of mines of magnetic ore, 

 had never been forgotten. Cecco d'Ascoli, satirist and 

 astrologer, fifty years later expressly affirmed in his bitter 

 poem, 1'Acerba 2 a most heterogeneous gathering of learn- 

 ing of all sorts, and hence appropriately termed "the 

 Heap" that both poles of the earth were magnetic and 

 exercised attraction, and perhaps he would have gone 

 further and found out the magnetic character of our globe, 

 and made who knows what other discoveries, if he had 

 not fallen foul of the Inquisition, which burned both him 

 and his books. 3 Between 1324 and 1508, however, great 

 intellectual changes had taken place. Where people 

 before assigned physical phenomena to causes entirely 

 evolved from their inner consciousness, and hence with- 

 out any foundation at all, they now explained them by 

 physical facts wrongly selected; which, on the whole, was 

 in the direction of progress. 



1 Humholdt: Cosmos. Lond. 1872, vol. v., 56. 



2 Poeti del Primo Secolo della lingua Ital. Florence, 1816. 



8 Lea: Hist, of Inquisition, vol. iii., 444. 



