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History of the Atlantic Cable & Undersea Communications
from the first submarine cable of 1850 to the worldwide fiber optic network

1858: Mr. Henley’s Gigantic Magneto-electric Machines

Introduction: On 1 September 1858 the last recorded message was transmitted over the Atlantic cable. Wildman Whitehouse had been fired by the company on 17 August and returned to London, although his high voltage induction coils remained at Valentia and continued to be used. And even after that last message, a dedicated technical staff at both Valentia and Newfoundland continued for several months to test the cable, speculating on what had gone wrong and how the cable might be revived.

Much opprobrium was heaped on Whitehouse for his use of the high voltage coils, which many believed had caused the failure of the cable (although recent research suggests a number of other contributing causes beyond his control). Accordingly, it is more than a little surprising to read in this article from the correspondent of the Daily News, published there on 28 September 1858 and printed in Lloyd’s Weekly London Newspaper on 3 October, that Mr Henley’s “gigantic magneto-electric machines” were now being tried on the cable. However, it is not clear from this or any other description of Henley’s machine just how much voltage it could generate.

On 17 September 1858 Cromwell Varley had reported from Valentia to the Board of the Atlantic Telegraph Company in London that “It is not at all improbable that the powerful currents from the large induction coils have impaired the insulation, and that had more moderate power been used, the cable would still have been capable of transmitting messages”, so there were obviously still different (and conflicting) opinions on the best way to work the cable.

W.T. Henley arrived at Valentia on 8 September, and his large magneto-electric machine was used on the cable beginning on 20 September [North British Review, November 1858]. From the description in the article below, Henley’s device was even larger than the induction coil which Whitehouse had used, a far cry from the “magneto-electric machines which, in place of batteries, are used for working on all the telegraph lines in Ireland”. These instruments were the standard desktop devices, without induction coils.

Unfortunately, no examples of Henley’s gigantic machines are known, nor is there any more detailed description of them in the cable literature. Henley’s own report on his tests of the cable was sent to the Board on 30 September; the section dealing with his "magnetic machine" is appended below, and the full report was reprinted in a number of newspapers and other publications.

In October 1858 Wildman Whitehouse's associate Samuel E. Phillips responded to Henley's report by means of a letter published in the Morning Post, and a subsequent letter from Phillips to the Atlantic Telegraph Company's shareholders was reprinted in the Morning Chronicle.

--Bill Burns

Lloyd’s Weekly London Newspaper, Oct 3, 1858.


The correspondent of the Daily News, writing at Valentia says:–

Since my last communication no improvement has taken place in the electrical condition of the Atlantic cable; nor, indeed, until within the last few days have any operations or experiments (beyond those the results of which have already been communicated) been undertaken to ascertain the nature of the leakage in the cable, or the probability of working through it in its present condition. During each alternate hour the regular succession of signals previously alluded to are despatched, and during the intervals the galvanometers of Professor Thomson are watched for some indications of currents from the other side; but these, unfortunately, are seldom seen at all, and still more rarely can these slight deflections be depended on as currents from Newfoundland. However, there is still this much cause for satisfaction, that the fault does not get worse at any time, while it occasionally for a time improves. Considerable and distinct “reversals” from Newfoundland are discernible. The opinion prevalent among many here, that the principal fault in the cable is comparatively near shore, daily gains ground, and though Professor Thomson’s opinion is directly opposed to each a supposition, I cannot help thinking that there really is more in it than was at first supposed. For the reasons given in my last letter there is no doubt a fault existing in the cable upon the bank which divides the shoal water from the depths of the Atlantic, about 220 miles from the Irish coast. But this fault, without the existence of several minor faults nearer shore, would not account for the total interruption of the currents sent from either terminus. All that Professor Thomson, Mr. Henley, or Mr. Varley, can say respecting the fault is that it gives a resistance to the electric current equal to 300 miles of the cable. Bat it does not therefore follow that the interruption is 300 miles away, for by passing the current through a few yards of fine wire in a basin of salt water, the very same amount of resistance can be produced. Though the distant fault may tend to interrupt the small portion of the electrical current which passes the nearer faults, yet, if these more accessible ones were repaired, it is the opinion of many here competent to judge of the matter that the supposed loss of insulation out at sea would not materially affect the working of the line. The more recent advices from Newfoundland decidedly tend to strengthen the opinion that the main interruption is close to this place. Mr. Cyrus Field, in writing from America, says that “no messages have been received from Ireland since the 1st instant, though the insulation of the cable remained perfect.” Now, according to the experiments of Professor Thomson and others, it has been ascertained that a loss of insulation 300 miles from either shore would affect the currents sent from both ends equally, whereas if the defect were close to either station, the loss of insulation would only be apparent at the termination nearest to it. A very similar defect to the present occurred a short time ago In one of the North Sea cables. Mr. Varley and other scientific gentlemen tested the cable, and pronounced the defect to be 170 miles off. The cable was accordingly underrun, and out at a distance of thirty miles from the shore, when it was found that the defect was much nearer; and after a variety of other experiments had been tried, the faulty place in the cable was discovered not out at sea at all, but actually in the portions of the cable buried in the beach.

The practical tests cannot be obtained without underrunning and cutting the cable some distance from the coast. The operations will undoubtedly require fine weather to render them entirely successful. The usual season of fine weather, of which there has been very little this year upon this coast, is now almost over, and people down here already begin to look out for the commencement of those violent storms which render these parts of the Irish coast exciting, if not amusing, places of residence during the winter time. During October, which here, as well as in other parts of the United Kingdom, is usually a fine month, much might be done towards underrunning and repairing at least some of the damaged portion of the cable. There is certainly no time to be lost, for every week that the cable remains at the bottom diminishes the chance of its being raised from the more considerable depths should it be deemed necessary to do so. The Cork steamer, which arrived here on Wednesday last, brought Mr. Henley’s gigantic magneto-electric machines, which, as soon as they were landed, were put together, and got into operation on the following day. The machines are a slight modification of the magneto-electric machines which, in place of batteries, are used for working on all the telegraph lines in Ireland, though of course on a gigantic scale, being the largest and most powerful instruments of the kind yet constructed. The two permanent magnets from which the electric induction is obtained are each composed of thirty horse-shoe steel magnets, two feet and a half long, and from four to five inches broad. The induction coils attached to these each contain six miles of wire. Some idea of the power of this instrument may be gathered from the fact, that a shock from it, if passed through the human body, would be sufficient to destroy life. With the aid of this instrument Mr. Henley hopes to be able to work through the cable during some part of each day, even if the fault should prove irreparable. The smaller instruments of the same kind which are used by the Magnetic Telegraph company have been found to work better over badly insulated lines than any other description of instrument. What is undoubtedly true of faulty underground lines may prove so also of the Atlantic cable; and certainly as far as the experiments have already gone, Mr. Henley’s instrument seems likely to work through the line in its present condition if anything will do it.

A variety of experiments have been tried lately, both by Professor Thomson and Mr. Henley, to discover the relative power of different electrical currents to pass a fault. For this purpose the wire connected with the cable was stripped at its gutta percha covering in one place, and the fault immersed in water, and the relative amount of electricity which passed by the fault into the cable was accurately measured by a delicate galvanometer. It was found that a current of electricity direct from the battery cells was hardly perceptibly reduced in quantity after passing by a break in the insulation an eighth of an inch long. The reduced current from Mr. Henley’s magneto-electric machine was slightly interrupted in passing the same fault, but the high tension induced coil currents, which have been used from the first in sending messages from both sides of the ocean, were found to be almost entirely stopped by it. These experiments, besides showing the kind of electricity best adapted for working through the cable in its present defective state, also show most conclusively that one defect in the insulation, however great, would not be sufficient to interrupt the communication; there must be several faulty places in the line. That some, if not the majority, of these places are close to the land there can be very little doubt.

The soundings from Valentia for about sixty miles to sea show a rocky and irregular bottom, which, indeed, the precipitous cliffs which line the coast and the numerous lofty islands which surround it in all directions would show without the aid of the sea lead. Over these submarine hills and valleys a very strong current sweeps, to resist which it would require a cable at least three times as thick as the one now in use. The small piece of the Atlantic cable which connects Valentia island with the mainland, a distance of about an English mile, is repeatedly being cut and injured by the tide drifting it across the rocky bottom; and it is quite possible to suppose that the rapid current outwards from the broad estuary of Dingle bay may have the same effect upon the thin Atlantic cable which runs across its mouth. It is the unanimous opinion of nearly all here that the laying of ten or twelve miles of the thick shore end of the cable would tend permanently to obviate a great many of the difficulties with which the electrical department of this undertaking has been hitherto interrupted.

Report of W.T. Henley to the Atlantic Telegraph Company (extracts):

On the 5th of October, 1858, Mr. George Saward, the Secretary of the Company, officially authorized the publication of the following report in the London Times:

To the Chairman and Directors of the Atlantic Telegraph Company:

Valentia, Sept. 30, 1858.

Gentlemen: In accordance with your instructions, I have, since my arrival here on the 8th instant, carefully tested the cable at various times, and with different degrees of battery power, and have found its insulation seriously impaired, and the results of the testing led to the conclusion that the injury is at a considerable distance from this (very nearly 300 miles of the cable apparently intervening between this point and the fault).

As I think it right you should know on what grounds and by what modes of operation I and others have arrived at this conclusion, and as you may also like to be informed as to some of the phenomena of electrical science as shown in connection with this cable, I have ventured to go a little into detail, hoping thereby to convey some information that may not be unacceptable.


On the arrival of my large magnetic machine, I put it together, and connected it with the cable, and have used it a part of every day since, sending at some times reversals and at others words and sentences. I am unable to tell whether they were received and understood, but hope to find such has been the case on the receipt of intelligence from Newfoundland. Having a machine at one end only, it will, of course, be evident that, even if they received properly, they could not have answered better than before. But we have been encouraged by seeing more reversals and attempts to send words from them lately than before. I will leave the machine here; it will be worked at stated hours each day by the assistants until the days fixed upon in October, when it will be used alternately as arranged with the battery and coils. The clerks at each end will then act according to preconcerted arrangements, which I hope will have the effect of renewing telegraphic correspondence. If that is not accomplished, probably the best thing then would be to raise the cable for about 15 miles out and test. I cannot say I have any hopes of the fault being found within that distance, but as it would not be attended with any trouble or risk I think it worth the trial. If the injury is in the deep soundings, I believe any attempt to raise it would be the means of breaking the cable and losing the end altogether. If the state of the cable should not get worse I am still in hopes of its being rendered workable by transmitting signals slowly, by having delicate receiving apparatus, and by adopting means for neutralizing the earth current. Professor Thomson has partially succeeded in the latter object by throwing into the receiving end of the line feeble currents of different values, from one cell to one twentieth of a cell, in opposition to the earth current. I am, gentlemen, yours obediently,

W.T. Henley, Telegraph Engineer.
46 John-street-road, Clerkenwell.

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