TOO THE APPLICATIONS OF PHYSICAL FORCES. [BOOK v. 



wire of which the circuit is to be closed. Immediately the explosion 

 takes place. Experiments carried on for some years have been 

 eroWned, it appears, with success. 



Paris, during the siege, had the neighbourhood of its ramparts 

 and forts protected by a network of torpedoes. But as no grand 

 assault took place against the whole city on the part of the besieging 

 army, this systeni of defence, although perfectly organized, necessarily 

 had only a preventive office. 



