Laying The Cable—“Faults” and Fault-Finding—Anxieties, Accidents, and other Matters.  
Come with us now, good reader, to another and very different scene—out upon the boundless sea. The great Atlantic is asleep, but his breast heaves gently and slowly like that of a profound sleeper.
 
The Great Eastern looks like an island on the water—steady as a rock, obedient only to the rise and fall of the ocean swell, as she glides along at the rate of six knots an hour. All is going well. The complicated-looking paying-out machinery revolves smoothly; the thread-like cable passes over the stern, and down into the deep with the utmost regularity.
 
The shore-end of the cable—twenty-seven miles in length, and much thicker than the deep-sea portion—had been laid at Valentia, on the 22nd of July, amid prayer and praise, speech-making, and much enthusiasm, on the part of operators and spectators. On the 23rd, the end of the shore cable was spliced to that of the main cable, and the voyage had begun.
 
The first night had passed quietly, and upwards of eighty miles of the cable had gone out of the after-tank, over the big ship’s stern, and down to its ocean-bed, when Robin Wright—unable to sleep—quietly slipped into his clothes, and went on deck. It was drawing near to dawn. A knot of electricians and others were chatting in subdued tones about the one subject that filled the minds of all in the ship.
 
“What! unable to sleep, like the rest of us?” said Ebenezer Smith, accosting Robin as he reached the deck.
 
“Yes, sir,” said Robin, with a sleepy smile, “I’ve been thinking of the cable so much that I took to dreaming about it when I fell asleep, and it suddenly turned into the great sea-serpent, and choked me to such an extent that I awoke, and then thought it better to get up and have a look at it.”
 
“Ah! my boy, you are not the only one whom the cable won’t let sleep. It will be well looked after during the voyage, for there are two sets of electricians aboard—all of them uncommonly wide awake—one set representing the Telegraph Construction and Maintenance Company, under Monsieur de Sauty; the other set representing the Atlantic Telegraph Company, under Mr Varley and Professor Thomson. The former are to test the electrical 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 and 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 from the shore, as well as every message sent by us in reply, has to travel through the entire length of the cable, namely about 2400 miles, and as every mile of distance increases this unwillingness, or resistance, we have to increase the electrical power in the batteries in proportion to the distance to which we want to send our message. D’you understand?”
 
“I think I do, sir; but how is the exact amount of resistance tested?”
 
Mr Smith smiled as he looked at the earnest face of his young questioner.
 
“My boy,” said he, “you would require a more fully educated mind to understand the answer to that question. The subtleties of electrical science cannot be explained in a brief conversation. You’ll have to study and apply to books for full light on that subject. Nevertheless, although I cannot carry you into the subject just now, I can tell you something about it. You remember the testing-room which I showed you yesterday—the darkened room between the captain’s state-room and the entrance to the grand saloon?”
 
“Yes, sir, I remember it well,” responded Robin,—“the room into which the conducting-wires from the ends of the cable are led to the testing-tables, on which are the curious-looking galvanometers and other testing machines.”
 
“Just so,” returned Smith, pleased with his pupil’s aptitude. “Well, on that table stands Professor Thomson’s delicate and wonderful galvanometer. On that instrument a ray of light, reflected from a tiny mirror suspended to a magnet, travels along a scale and indicates the resistance to the passage of the current along the cable by the deflection of the magnet, which is marked by the course of this speck of light. Now, d’you understand that, Robin?”
 
“I—I’m afraid not quite, sir.”
 
“Well, no matter,” rejoined Smith, with a laugh.
 
“At all events you can understand that if that speck of light keeps within bounds—on its index—all is going well, but if it travels beyond the index—bolts out of bounds—an escape of the electric current is taking place somewhere in the cable, or what we call a fault has occurred.”
 
“Ah, indeed,” exclaimed Robin, casting a serious look at the cable as it rose from the after-tank, ran smoothly over its line of conducting wheels, dropped over the stern of the ship and glided into the sea like an an endless snake of stealthy habits. “And what,” he added, with a sudden look of awe, “if the cable should break?”
 
“Why, it would go to the bottom, of course,” replied Smith, “and several hearts would break along with it. You see these two gentlemen conversing near the companion-hatch?”
 
“Yes.”
 
“One is the chief of the electricians; the other the chief of the engineers. Their hearts would probably break, for their position is awfully responsible. Then my heart would break, I know, for I feel it swelling at the horrible suggestion; and your heart would break, Robin, I think, for you are a sympathetic donkey, and couldn’t help yourself. Then you see that stout man on the bridge—that’s Captain Anderson—well, his heart would—no—perhaps it wouldn’t, for he’s a sailor, and you know a sailor’s heart is too tough to break, but it would get a pretty stiff wrench. And you see that gentleman looking at the paying-out gear so earnestly?”
 
“What—Cyrus Field?” said Robin.
 
“Yes; well, his heart and the Atlantic Cable are united, so as a matter of course the two would snap togethe............