LINE CONSTRUCTION. 
135 
In a new form of earth-borer invented by Marshall, the 
anger is suppressed, and a plate that forms a screw with 
cutting edges takes its place. The new apparatus seems cheaper 
than the other, and in light soils it can be worked by a single 
labourer. 
The posts are fixed quite vertically, except in curves, 
where they usually have a slight outward inclination given to 
them. 
The mean rate of progress of ten men, two layers, and 
a foreman, is one and a half miles a day in clayey or sandy 
soil. 
When the posts have been fixed throughout the whole 
course, the placing of the wires is proceeded with. This opera¬ 
tion is generally effected on one wire at once. A gang will on 
the average lay six miles of wire per day. Three workmen lay 
the wire along the ground; two draw it at one end, and the 
third unwinds it from a bobbin. These men advance continu¬ 
ously, and temporarily connect the ends of the wires. 
Three workmen make the permanent junction of the wires, 
and solder them ; two others, provided with ladders, place the 
wire on the insulators. If there are many high posts, another 
man will be required, either to carry a long ladder, or to go up 
the posts by means of climbing apparatus. 
The remainder of the gang pushes along the little truck 
laden with the requisite tools and materials, such as iron wire 
to lay another line if required. When they reach the terminal 
post, the soldering workmen unite with those behind to stretch 
the wire. For this operation, six or eight men are required 
according to the size of the wire. One turns the drum of the 
stretcher, whilst the rest draw the wire by means of pinchers ; 
the bend at this time allowed to the wire, is generally irregular 
and excessive. After all the wires are placed, the readjust¬ 
ment of the whole is proceeded with. 
A gang working ten hours, generally completes the laying of 
two and a half miles of supplementary wire, including the fixing 
of insulators. 
Aerial lines in English Towns .—In certain large places in 
England, where the construction of subterranean lines was 
undesirable, and where it was not possible to support the 
wires on posts or brackets, a system of over-house telegraphs has 
