CONDUCTING WIRES. 
109 
substituted: About 6 or 7 inches lengths of the wires are laid 
alongside each other and pressed together by a vice applied in 
the middle. The free end of each wire is then wound tightly 
in a spiral form round the continuous part of the other, and 
the middle is soldered. 
If the wires are not galvanized, their connection is completed 
by joining them with a thin cop>per wire soldered at each end 
of the double spiral. The copper wire is wound several times 
round the spirals, to prevent it from being broken, if these 
should come together while the wire is being stretched. To 
form the spiral, the ends are held in a pair of pinchers while a 
tool shaped like a hook is made use of. The wire round which 
the other is to be w T ound is placed within the hook, and the end 
of that which is to be wound on is caught in a notch formed in 
the curved part of the tool, which is then turned by hand. The 
twists obtained in this way are very close and regular, and are 
very quickly made (figs. 42 and 43). 
The following mode of joining, which is used on several 
lines, is one of the best as regards conductivity and strength; 
Fig. 44. 
but it requires much time and care in its formation, and pre¬ 
sents some practical difficulties as regards the soldering. The 
wires are placed alongside of each other after the ends have 
been bent into a loop ; they are strongly bound together by 
means of a thin iron wire wound over the whole extent of the 
loops, and the whole is dipped into melted solder (fig. 44). 
The kind of joint used in France seems to produce a good 
contact and to afford sufficient resistance to strain. It con¬ 
sists of a hollow collar of galvanized iron, provided with a 
groove on one of its faces. Into this the wires are introduced, 
their ends are flattened by the hammer, and solder is poured in 
through the openings. 
Posts .—The posts used for supporting the conducting wires 
are made of fir, pine, or larch, and are saturated with sulphate 
of copper according to Boucherie’s process. They are also 
