FLYING-FISH. 49 



ciently known, although the author just named has 

 shown that fuel in general separate with great facil- 

 ity after the period of fructification. 



Beyond 22 of latitude they found the surface of 

 the sea covered with flying-fish (Exocetus volitans), 

 which sprang into the air to a height of twelve, fif- 

 teen, and even eighteen feet, and sometimes fell on 

 the deck. The great size of the swimming-bladder 

 in these animals, being two-thirds the length of their 

 body, as well as that of the pectoral fins, enable 

 them to traverse in the air a space of twenty-four 

 feet, horizontal distance, before falling again into the 

 water. They are incessantly pursued by dolphins 

 while under the surface, and when flying are attacked 

 by frigate-birds, and other predatory species. Yet 

 it does not seem that they leap into the atmosphere 

 merely to avoid their enemies ; for, like swallows, 

 they move by thousands in a right line, and always in 

 a direction opposite to that of the waves. The air 

 contained in the swimming-bladder had been sup- 

 posed to be pure oxygen ; but Humboldt found it to 

 consist of ninety-four parts of azote, four of oxygen, 

 and two of carbonic acid. 



On the 1st July they met with the wreck of a ves- 

 sel, and on the 3d and 4th crossed that part of the 

 ocean where the charts indicate the bank of the 

 Maal-Stroom, which, however, is of very doubtful 

 existence. As they approached this imaginary whirl- 

 pool, they observed no other motion in the waters 

 than that produced by a current bearing to the north- 

 west. 



From the time when they entered the torrid zone 

 (the 27th June), they never ceased to admire the 

 nocturnal beauty of the southern sky, which grad- 

 ually disclosed new constellations to their view. 

 " One experiences an indescribable sensation," says 

 Humboldt, " when, as he approaches the equator, and 

 especially in passing from the one hemisphere to the 

 other, he sees the stars with which he has been fa- 

 E 



