280 THE BOTTOM OF THE SEA. 



by means of a conduit-tube furnished with a stop- 

 cock. By means of a pump the vessel could be filled 

 with water at will. To cause the vessel to sink it 

 was only necessary to allow the water to penetrate 

 these tubes ; its ejection caused the vessel to rise. A 

 screw worked at the stern. 



Villeroy's structure was 35 feet in length, and 44 

 inches in diameter. Tlie sci ew was 3 feet in diameter. 

 By lighting the bottom of the sea by means of an 

 electric light placed in the interior of the vessel, a 

 convenient method of exploration would be obtained, 

 at least in the neighbourhood of the coasts. 



This vessel, built during the American war contem- 

 poraneously wath the production of the monitors, 

 which may be said to have saved the North from the 

 humiliation of defeat, is a worthy companion of the 

 torpedo — that terrible instrument of war, which, in a 

 moment of supposed security, is capable of destroying 

 the most formidable ship of war with even more cer- 

 tainty than a tempest. 



10. Employment of Torpedoes in clearing Cliannels and the 

 Entrances to Ports. 



In our age — which may be called an age of progress, 

 since it has witnessed the development of so many 



