64 COSMOS. 



Majorcans, and Catalans. The latter people, under the 

 guidance of their celebrated countryman, the navigator, Don 

 Jaime Ferrer, penetrated, in 1346, to the mouth of the Rio 

 de Ouro (23 40' KL.), on the Western Coast of Africa, and, 

 according to the testimony of Raymundus Lullus (in his 

 nautical work Fenix de las Maravillas del Orbe, 1286) the 

 Barcelonians employed atlases, astrolabes, and compasses, 

 long before Jaime Ferrer. 



The knowledge of the amount of magnetic variation is of 

 a very early date, and was simultaneously imparted by the 

 Chinese to Indian, Malay, and Arabian seamen, through whose 

 agency it must necessarily have spread along the shores of 

 the Mediterranean. This element of navigation, which is so 

 indispensable to the correction of a ship's reckoning, was then 

 determined less by the rising and setting of the sun than by 

 the polar star, and in both cases the determination was very 

 uncertain ; notwithstanding which, we find it marked down 

 upon charts, as for instance upon the very scarce atlas of 

 Andrea Bianco, which was drawn out in the year 1436. 

 Columbus, who had no more claim than Sebastian Cabot, 

 to be regarded as the first discoverer of the variation of 

 the magnetic needle, had the great merit of determining 

 astronomically the position of a line of no variation 2^ 

 east of the Island of Corvo, in the Azores, on the 13th 

 of September, 1492. He found, as he penetrated into the 

 western part of the Atlantic Ocean, that the variation 

 passed gradually from north-east to north-west. This obser- 

 vation led him to the idea, which has so much occupied navi- 

 gators in later times, of finding the longitude by the position 

 of the curves of variation which he still imagined to be 

 parallel to the meridian. We learn from his ship's log, that 

 when he was uncertain of his position during his second 

 voyage (1496), he actually endeavoured to steer his way by 

 observing the declination. The insight into the possibility 

 of such a method was undoubtedly that uncommunicable 

 secret of longitude, which Sebastian Cabot boasted on his 

 deathbed of having acquired through special divine mani- 

 festation. 



The idea of a curve of no declination in the Atlantic was 

 associated in the easily excited fancy of Columbus with 

 other somewhat vague views of alterations of climate, of an 



