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Story of the Atlantic Cable

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<h3>CHAPTER XI THE INQUEST</h3> <div class="blockquot">Expert Trials—Expert Evidence </div> THE great historical sea-line having collapsed, some of the foremost of the electrical profession were called in—first to determine the nature of the interruption with a view to possible remedy, next to elicit the cause. Expert Opinions on the Failure.—Mr. Cromwell Fleetwood Varley, the electrician to the Electric Telegraph Company, Mr. E. B. Bright, the chief of the “Magnetic” Company; and Mr. W. T. Henley, the well-known telegraph inventor, were severally requested by the “Atlantic” Company to report on the subject in conjunction with Sir Charles Bright and Professor Thomson. First of all the dead line was subjected to a series of tests. For this, resistance-coils and Messrs. Bright’s apparatus for ascertaining the position of a fault were employed. There was every evidence of a serious electrical leakage about 300 miles from Valentia, but there did not appear to be any fracture in the conductor, as exceedingly weak currents still came through fitfully. According to the above location, the main leak through the gutta-percha envelope was in water of a depth of about two miles. At that time means were not devised for grappling and lifting{156} a cable from such depths. But from independent tests by Thomson and Bright, it appeared likely that the Valentia shore end was also especially faulty. Accordingly, it was underrun from the catamaran-raft (previously used in 1857) for some three miles, but, on being cut at the farthest point at which it was found possible to raise the cable, the fault still appeared on the seaward side. The idea of repairs had, therefore, to be abandoned, and the cable was spliced up again. The conductor being again intact, efforts were made to renew signals with the curb-key recently invented by Messrs. Bright. By means of this, currents of opposite character were transmitted so that each signaling current was followed instantly by one of opposite polarity, which neutralized, by a proportionate strength and duration, all that remained of its predecessor. Though this was the right principle on which to work, the “patient” was too far gone, and all efforts proved unavailing; for signaling purposes the poor cable was defunct. Having dealt with the nature of the interruption, we now come to the cause. It was first of all abundantly clear from the station-diaries kept by the electricians at Valentia and Newfoundland, and by other irrefragable evidence, that when the laying was completed, and the cable ends were handed over to them from the ships on August 5th, all was in good working order. The authorities were unanimous in their opinion. Mr. C. F. Varley declared that “had a more moderate power been used, the cable would still have been capable of transmitting messages.” In giving extra force to the above opinion, Mr. Varley{157} described an experiment he had made on the cable in conjunction with Mr. E. B. Bright: <div class="blockquot">We attached to the cable a piece of gutta-percha-covered wire, having first made a slight incision, by a needle-prick, in the gutta-percha to let the water reach the conductor. The wire was then bent, so as to close up the defect. The defective wire was then placed in a jar of sea-water, and the latter connected with the earth. After a few momentary signals had been sent from the five-foot induction-coils into the cable, and, consequently into the test-wire, the intense current burst through the excessively minute perforation, rapidly burning a hole nearly one-tenth of an inch in diameter, afterward increased to half an inch in length when passing the current through the faulty branch only. The burned gutta-percha then came floating up to the surface of the water, while the jar was one complete glow of light. </div> Professor Hughes, the inventor of the type-printing telegraph, and, subsequently, of the microphone, considered that “the cable was injured by the induction-coils, and that the intense currents developed by them were strong enough to burst through gutta-percha.” Professor Wheatstone gave a similar opinion. Some one inquired of the electrician whether, if any one touched the cable at the time when the current was discharged from the induction-coil, he would receive a shock sufficiently strong to cause him to faint. It was admitted in reply that “those who touched the bare wire would suffer for their carelessness, though not if discretion be exercised by grasping the gutta-percha only.” The chairman of the company (the Right Honorable J. Stuart Wortley, M.P.), in the course of a deputation to Lord Palmerston later on, stated{158} that “far too high charges of electricity were forced into the conductor. It was evidently thought at that time by certain electricians that you could not charge a cable of this sort too highly. Thus they proceeded somewhat like the man who bores a hole with a poker in a deal board; he gets the hole, to be sure, but the board is burned in the operation.” Professor Thomson (now Lord Kelvin), writing in 1860, expressed the following opinion: <div class="blockquot">It is quite certain that, with a properly adjusted mirror-galvanometer as receiving-instrument at each end, twenty cells of Daniell’s battery would have done the work required, and at even a higher speed if worked by a key devised for diminishing inductive embarrassment; and the writer—with the knowledge derived from disastrous experience—has now little doubt but that, if such had been the arrangement from the beginning, if no induction-coils and no battery-power exceeding twenty Daniell cells had ever been applied to the cable since the landing of its ends, imperfect as it then was, it would be now in full work day and night, with no prospect or probability of failure.[50] </div> Summing up the cause of the untimely ending to the ill-used cable, perhaps the concisest verdict would be, in mechanical-engineering parlance, that “high-pressure steam had been got up in a low-pressure boiler.{159}” <h2>PART III INTERMEDIATE KNOWLEDGE AND ADVANCE</h2> {160} <div style="break-after:column;"></div>

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