CANARY ISLANDS. 15 



*' In this manner, the waters of the Atlantic, between the 

 parallels of 11° and 43°, are carried round in a continual 

 whirlpool, which Humboldt calculates must take two years 

 and ten months to perform its circuit of 13,118 miles. 

 This great current is named the Gulf Stream. Off the 

 coast of Newfoundland a branch v^eparates from it, and 

 runs from S.W. to N.E. towards the coasts of Europe." 



This current is of great utility to the navigator, who may 

 judge, with a degree of certainty, of his situation, and of 

 the proximity of his approach towards the coast of the 

 United States. When he enters the borders of it, the in- 

 creased temperature of the water, its strong saltness, its 

 intense azure color, and the large quantities of sea-weed 

 (Fiicus) which floats along its surface, as well as the ele- 

 vated heat of the surrounding atmosphere, all indicate, 

 even in winter, that lie has reached this noble Gulf 



On the 11th instant, in latitude 39° 54', and in longitude 

 69° 41', I observed some fragments of fucus, a kind of sea- 

 weed which grows on submarine rocks, as well as three 

 species of medusae, floating in a south-westerly direction, 

 propelled by the counter current near the western edge of 

 the gulf 



The medusae are animals consisting of a tender gelati- 

 nous mass of different fibres, supplied with arms or tentacu- 

 lar processes proceeding from their lower surface. They 

 are marked with various colors, which, by the reflection of 

 the sun's rays, create a beautiful contrast with the azure 

 tint of the ocean. The larger species when touched by the 

 hand, cause a slight stinging and redness ; hence they are 

 commonly called sea-nettles. By gently agitating them in 

 the dark, they will emit light. '' When a very irritable in- 

 dividual is placed on a tin plate, and the latter is struck 

 with a piece of metal, the vibrations of the tin are sufficient 

 to make the animal shine. Sometimes, on galvanizing 

 medusse, the phosphorescence appears at the moment when 

 the chain closes, although the exciters are not in direct 

 contact with the body of the subject. The fingers, after 

 touching it, remain luminous for two or three minutes. 

 Wood, on being rubbed with medusse, becomes luminous, 

 and after the phosphorescence has ceased, it may be 



