Whenever separate lengths of the gutta percha covered core were to be joined together, the gutta percha was scraped away for a short distance from the ends, and these were made to overlap. A piece of copper wire was then attached by firm brazing, an inch or two beyond the joint on one side, tightly bound round until it reached to the same extent on the other side, and then was there firmly brazed on again. A second binding was next rolled over the first in the same fashion, and extended a little way beyond it, and finally several layers of gutta percha were carefully laid over, and all round the joint by the agency of hot irons. If the core on each side of the joint was dragged opposite ways until the joint yielded, the outer investment of the wire unrolled spirally as the ends were pulled asunder, and so the conducting continuity of the strand was maintained, although the mechanical continuity of the strand itself was broken. The two-mile coils of completed and proved core were wound on large drums with projecting flanges on each side, the rims of which were shod with iron tires, so that they might be rolled about as broad wheels, and made to perform their own locomotive offices as far as possible. When the core was in position on these channelled drums, the circumference of the drum was closed in carefully by a sheet of gutta percha, which thus constituted its core-filled channel a sort of cylindrical box or packing case. In this snug nest each completed coil of core was wheeled and dragged away to be transferred to the manufactory, either at Birkenhead or Greenwich. The core-filled drums, having arrived at the factory of the Cable, the drums were mounted by axles, and kept ready so that one extremity of the length of core might be attached to the Cable as it was spun out, when the drum previously in use had been exhausted. During the unrolling of the core from the drum, it was wound tightly round by a serving of hemp, saturated with a composition made chiefly of pitch and tar, the winding being effected by revolving bobbins as the core was drawn along. This hempen serving constituted a bed for the external coat of metallic wires, and prevented the insulating sheath of gutta percha from being injured by pressure during the final stage of the construction. Each new length of core was attached to the Cable by precisely the same operation as that used at the gutta percha works in joining the two-mile coils for testing; shortly before an old drum was exhausted, its remainder was rapidly pulled off and placed in the joiner’s hands, so that it might be made continuous with the core on a new drum, before the outgoing Cable began to draw upon it.