156 
THE TELEGRAPH 
trough is withdrawn the moment the machine stops. The 
bitumen-covered cable is made to assume a round shape, by 
passing through a gauge that throws back the excess of material 
into the vessel where it is kept melted (fig. 98). 
The wires used for making cables are generally galvanized; 
and this, with the protection given by the coating of Clarke’s 
Fig. 97. 
bituminous composition, ensures the preservation of submarine 
lines. 
A cable covered with good iron should support a ton for 
each pound weight of iron in a yard of its length. The 
numbers of wires used always range between 9 and 18, and 10 
or 12 wires make a good flexible cable. Near the shore, the 
dimensions of the outer armour are considerably increased, in 
order to protect the cable against abrasions on rocks or injury 
from anchors. The shore cables have commonly a weight of 
9 to 12 tons per knot, and some weigh as much as 20 tons. 
A shore cable of the largest size is shown in fig. 99, which 
represents the shore cable of the French Atlantic line. The 
strands plaited with three wires make these cables much more 
manageable than if they were covered by solid wires. 
