202 ELECTRICITY FOR BLASTING 



These connections, though of a very rough description and most readily prepared 

 by any soldier, were thoroughly effectual. No instance occurred, in tho -whole of 

 the experiments, of tho failure of a charge, which could bo attributed to an imperfect 

 connection of its branch wire with tho main wire. 



The following was the method adopted for connecting the fuzes with their respec- 

 tive branch wires and with tho earth : 



The fuzes, as they were manufactured, were always fitted with two pieces of 

 covered wire twisted together, fig. 786, which were tightly fixed into their proper 



786 



positions by forcing a short pin of copper-wire into the holes of tho fuze-head. They 

 were thus ready for insertion into tho bag or other receptacle containing tho charge 

 of gunpowder, the ends of tho covered wires protruding from tho opening of the 

 latter to a convenient distance for effecting the junction with the branch and earth- 

 wires. Tho extremities of one of the fuse-wires and of a branch wire (from both of 

 which the gutta-percha was removed to a distance of about two inches) were con- 

 nected by hooking them firmly one in tho other with pliers (in the manner shown in 

 fig- 787). A piece of fine copper binding wire was then twisted over the whole of 



787 



the connection, and the joint was finally enclosed in a small wrapping of oiled canvas, 

 in a manner similar to that adopted at the principal junction with the main wire. 



The extremity of the other fuze-wire was attached to an uncovered copper- wire, 

 of sufficient length to bring the whole of the charges into connection with each 

 other in this manner. The wire was fixed in a convenient position by being twisted 

 round short stakes or pickets driven into the ground, and 

 its extremities were buried in the earth, being attached 

 either to spades, as already described, or to zinc plates 

 about eight inches square. 



The experiments instituted at Chatham witli the object 

 of applying the magneto-electric current to the ignition 

 of submarine charges were attended with greater diffi- 

 culties than those which served to test the system in its 

 application to land operations ; nevertheless, the results 

 tiltimately attained were also of a character to lead to 

 definite and favourable conclusions. 



The method of establishing the connections of a charge 

 with the wire and tho earth differed naturally in some 

 respects from tho mode of proceeding already described. 

 The charges of powder were contained in canisters of 

 block tin carefully soldered so as to bo watertight. 1 The 

 fuze, with two wires attached as before, the one a few 

 inches longer than tho other, was inserted into the charge, 

 and fixed in its proper position in the canister by means 

 of a loose-fitting bung, (scc/y. 788) pushed a little dis- 

 tance into the neck, and cut out on one side, so as to 

 admit of the passage of tho longer insulated wire, while 

 tho bare part of the shorter wire was firmly pressed by 

 tho cork against the inside of the neck. The latter w.-is 

 then completely filled up with molted gutta-percha, and 

 tho extremity of the short uncovered wire was bent 

 back over its side, so as to be in close contact with 

 tho metal surface. In this manner, tho enclosed fuze 

 was brought into good metallic connection with the wot 

 earth, or water, by which the canister was surrounded. 

 Tho insulated wire, projecting from tho mouth of tho canister, was connected with 

 one of the branch wires in tho manner already described ; but in order thoroughly to 

 protect tho connection from the water, in which it would become immersed, a piece of 



1 Any vessels of this material, such as turpentine cans, may be employed, provided they be per- 

 fectly coated inside with marine glue, or some other description of varnish. 



