CHAP. VIII. ] 



THE ELECTRIC LIGHT. 



695 



a very simple mechanism plunges all the zincs into the liquid at the 

 same time. This process, which had been abandoned for those we 

 are about to describe, has for several years past been resumed and 

 improved. 



The method of blasting by the spark from Ruhmkorff's induction 

 coil was inaugurated at the great works at Cherbourg. This method, 

 proposed by M. Du Montcel, was not at first successful ; the 

 heating power of the spark at the distance at which it was necessary 

 to make the explosion was not sufficient to kindle the powder. 

 Fortunately an English engineer, Mr. Statham, invented a fuse 



FIG. 449. Stat h;uu's fuse for exploding 

 mines. 



FIG. -150. Chambers of mines. 



whose inflammability is much greater than that of ordinary fuses. 

 M. Ruhmkorff adopted the new invention, and success completely 

 crowned his attempts. This new kind of fuse is arranged as 

 follows : 



It consists of two pieces of red copper wire, inclosed in gutta- 

 percha covering, the free extremities, A B, of which, after being twisted 

 back, are introduced in a kind of vulcanized gutta-percha capsule. 1 The 



1 That is, combined with sulphur ; contact with a copper wire forms a very 

 inflammable deposit of sulphur. 



