SUBMARINE VESSELS. 239 



his expeditions, but it has not much extended tneir 

 radius. In fact, the pressure supported by tne in- 

 trepid explorer augments by one atmosphere when 

 he has reached a depth of 32 feet ; it soon becomes 

 80 great as to involve conditions in which it would be 

 impossible to live. Asphyxia, ravenous monsters, and 

 darkness, are not therefore the only obstacles which 

 man has to encounter in his submarine explorations. 

 He cannot descend into the immense oceanic valleys 

 as he faces tlie cold and rarefaction of the air on the 

 high mountains of the terrestrial surface. Beyond 

 the region of the monsters he must enter the realms 

 of darkness, and, should he go further still, encounter 

 sure destruction. 



Who can form an idea of the immense clianges 

 which would result if men were able to travel freely 

 under the surface of the waters? Where would 

 be the natural frontiers which politicians so much 

 desiderate ? Man darting through the air like a bird ; 

 locomotives competing with the eagle in point of 

 speed, and losing themselves in the midst of the 

 clouds; powerful machines plunging beneath the 

 oceanic tempests, and scattering in terrified hosts 

 the multitudinous inhabitants of the sea! Who 

 would dare to entertain for one moment dreams or 

 aspirations of so chimerical a nature ? Great minds 

 liave nevertheless devoted their labours and thoughts 



