THE FIELD TELEGRAPH. 
145 
the zinc plate ( z ) is suspended by means of the india-rubber 
cover (I). The whole is placed in the india-rubber vessel ( [i ), 
and a copper collar ( y ) is added, to which a connecting wire 
can be attached. This battery has the advantage of being very 
portable, while the india-rubber cover prevents the charge of 
sulphate of mercury from being spilt by the motion of the waggon. 
The line may be either an aerial or a ground wire, or a com- 
bination of both, the former being stretched on poles, while 
the latter is insulated by being enclosed in a light cable, about 
half an inch thick, and laid along by the road sides or across 
the fields. The uninsulated wire and the cable are both issued 
to the telegraph corps coiled on small drums, several of which 
are carried by each store-waggon. In those companies which 
are to erect a wire stretched on poles, the waggon carries five 
English miles of uninsulated galvanised iron wire, one mile 
insulated in gutta percha, 1,000 yards of the cable, and 200 
poles with insulators attached, all the wire being coiled on 
twelve drums. If it is intended to lay a ground line, the 
waggon carries eleven drums of the cable, one of wire covered 
with a light coat of gutta percha and tarred hemp, and a few 
poles and insulators, for carrying the line across small hollows, 
or raising it overhead in crossing roads. Beside these stores 
the waggon contains all the tools necessary for the work, and a 
light step-ladder is hung underneath it. 
The wire is uncoiled from the drums by placing them suc- 
cessively on a hand-barrow, from which it is paid out as the 
barrow is carried along. The hand-barrow (fig. 3) consists of 
a light iron frame, with wooden legs and handles, which are 
made to fold up when not in use. On this frame the drum (a) 
is placed ; one man carries it in front and two behind, the wire 
uncoiling and running out between them. A wheel-barrow 
(fig. 4) is sometimes employed, and is improvised for this 
purpose by attaching iron handles (d) to the step-ladder (66) 
and placing it on a pair of light iron wheels (c), the drum (a) 
being hung in a socket near the top of the ladder. 
The poles are made of well-seasoned and selected red pine, 
about 12 ft. long and a little more than an inch thick. At the 
bottom is an iron point for fixing them in the ground, and at the 
top a socket ( s , fig. 6) of the same metal, with a hollow screw to 
receive the spindle or stem of the insulator. This consists of 
an iron spindle (6), with a male screw cut in it, which sup- 
ports either a cap of gutta percha ( g ) or an earthenware cup 
surmounted by a metal bell. In both cases there is on the top 
of the insulator a metal hook (a), in which the line wire is hung. 
There are also insulators, the spindles of which terminate in 
spikes or sharp screws for driving into walls and trees, thus 
saving the trouble of erecting a post (fig. 9). 
VOL. XIII. — NO. LI. L 
