THE TELEGRAPH. 
154 
We here give (fig. 94) the section of the cable between Mar¬ 
seilles and Bone, in which kind of cable, Smith’s gutta-percha 
was first employed, In this cable, which was laid in 1870, the 
insulation attains 1482 megohms per knot, while the electro¬ 
static capacity is only 0*286 microfarads. The Eastern Tele¬ 
graph Company laid a second cable, in 1877, between Marseilles 
and Bone, and in this the dielectric was also Smith’s gutta¬ 
percha. Its insulation reached 8000 megohms per knot. 
The core of the cable is always covered with hemp or jute 
strands in a moist state and saturated with salts or with tannin. 
These strands are put round the core in two spiral layers by 
rope-spinning machines (fig. 95),. and they are applied with a 
certain amount of tension, so that the more the cable is stretched 
the greater strength they add to it. A considerable number of 
strands are used, and these are arranged round the core^in 
rather elongated spirals, so as to avoid any risk of knotting or 
twisting it, if one of the strands should happen to break, or 
not be as much stretched as the others. At the same time, on 
