FLYING-FISH — CONSTELLATIONS. 51 



pursued by doljihins while under the surface, and when chap. iv. 

 flying are attacked by frigate-birds and other predatory ^^. 7T~, 

 species. Yet it does not seem that they leap into the frigate birds, 

 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 

 supposed to be pure oxygen ; but Humboldt found it to 

 consist of ninety-four parts of azote, four of oxj^gen, 

 and two of carbonic acid. 



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

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

 ocean where the charts indicate the bank of the Maal- 

 Stroom, which, however, is of very doubtful existence. 

 As they approached this imaginary whirlpool they ob- 

 served no other motion in the waters than that produced 

 by a current bearing to the north-west. 



From tlie time when they entered the torrid zone Nocturnal 

 (the 27th June) they never ceased to admire the noc- ^w"'^ °^ 

 turnal beauty of the southern sky, which gradually 

 disclosed new constellations to their view. " One ex- 

 periences 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 familiar from infancy 

 gradually approach the horizon and finally disappear. 

 Nothing impresses more vividly on the inind of the 

 traveller the vast distance to which he has been re- 

 moved from his native country than the sight of a new 

 firmament. The grouping of the larger stars, the Aspect of tlit 

 scattered nebulse rivalling in lustre the milky- way, and ^'g^vg^ 

 spaces remarkable for their extreme darkness, give the 

 southern heavens a peculiar aspect. The sight even 

 strikes the imagination of those who, although ignorant 

 of astronomy, find pleasure in contemplating the celestial 

 vault, as one admires a fine landscape or a majestic site. 

 Without being a botanist, the traveller knows the torrid 

 zone by the mere sight of its vegetation ; and without 

 the possession of astronomical knowledge, perceives that 



