Page:Ballantyne--The Battery and the Boiler.djvu/92

 state of the cable, and to keep up signals with the shore every hour, night and day, during the voyage, while the latter are to watch and report as to whether the cable fulfils her conditions, as specified in the contract. So you see the smallest fault or hitch will be observed at once."

"Do you mean, sir," asked Robin in surprise, "that telegraphing with the shore is to be kept up continually all the voyage?"

"Yes, my boy, I do," answered Smith. "The lengths of the cable in the three tanks are joined up into one length, and telegraphing—for the purpose of testing it—has been kept up with the shore without intermission from the moment we left Ireland, and began to pay out. It will be continued, if all goes well, until we land the other end in Newfoundland. The tests are threefold,—first, for insulation, which, as you know, means the soundness and perfection of the gutta-percha covering that prevents the electricity from escaping from the wires, through the sea, into the earth; secondly, for continuity, or the unbroken condition of the conductor or copper core throughout its whole length; and, thirdly, to determine the resistance of the conductor, by which is meant its objection to carry our messages without vigorous application of the spur in the form of increased electrical power in our batteries. You see, Robin, every message sent to us