The copper strand of the Cable was rolled up on drums as it was completed, and was then taken from the drums to receive a coating of three separate layers of refined gutta percha; these brought its diameter up to about three-eighths of an inch. The coating of gutta percha was made unusually thick, for the sake of diminishing the influence of induction, and in order that the insulation might be rendered as perfect as possible. This latter object was also furthered by the several layers of the insulating material being laid on in succession; so that if there were accidentally any flaw in the one coat, the imperfection was sure to be removed when the next deposit was added. To prove the efficacy of the proceeding, a great number of holes were made near together in the first coating of a fragment of the wire, and the second coat was then applied in the usual way. The insulation of the strand was found to be perfect under these circumstances, and continued so even when the core was subjected to hydraulic pressure, amounting to five tons on the square inch. The gutta percha which was employed for the coating of the conducting strand, was prepared with the utmost possible care. Lumps of the crude substance were first rasped down by a revolving toothed cylinder, placed within a hollow case, the whole piece of apparatus somewhat resembling the agricultural turnip machine in its mode of action. The raspings were then passed between rollers, macerated in hot water, and well churned. They were next washed in cold water, and driven at a boiling-water temperature, by hydraulic power, through wire-gauze sieves, attached to the bottom of wide vertical pipes. The gutta percha came out from the sieves in plastic masses of exceeding purity and fineness, and those masses were then squeezed and kneaded for hours by screws, revolving in hollow cylinders, called masticators; this was done to get the water out, and to render the substance of the gutta percha sound and homogeneous everywhere. At each turn of the screw, the plastic mass protruded itself through an opening left for feeding in the upper part of the masticator, and was then drawn back as the screw rolled on. When the mechanical texture of the refined mass was perfected by masticating and kneading, it was placed in horizontal cylinders, heated by steam, and squeezed through them by screw pistons, driven down by the machinery very slowly, and with resistless force. The gutta percha emerged, under this pressure, through a die, which received the termination of both cylinders, and which at the same time had the strand of copper wire moving along through its centre. The strands were drawn by revolving drums between the cylinders, and through the die. They entered the die naked bright copper wire, and issued from it thick, dull-looking cords, a complete coating of gutta percha having been attached to them as they traversed the die. Six strands were coated