The New Atlantic Cable
WHEN the indefatigable Cyrus told our people, five years ago, that he was going to lay a telegraph-cable in the bed of the ocean between America and Europe, and place New York and London in instantaneous communication, our wideawake and enterprising fellow-citizens said very coolly that they should like to see him do it! — a phrase intended to convey the idea that in their opinion he had promised a great deal more than he could perform. But Cyrus was as good as his word. The cable was laid, and worked for the space of three weeks, conveying between the Old and New World four hundred messages of all sorts, and some of them of the greatest importance. Four years have elapsed since the fulfilment of that promise, and now Mr. Field comes again before the public and announces that a new Atlantic cable is going to be laid down, which is not only going to work, but is to be a permanent success; and this promise will likewise be fulfilled. You may shrug your shoulders, my friend, and look incredulous, but I assure you the grand idea will be realized, and speedily. I have been heretofore as incredulous as any one ; but having examined the evidence in its favor, I am fully convinced not only of the feasibility of laying a cable, and of the certainty of its practical operation when laid, but of its complete indestructibility. If you will accompany me through the following pages, my doubting friend, I will convince you of the correctness of my conclusions.
When the fact of the successful laying of the old Atlantic cable was known, there was no class of people in this country more surprised at the result than the electricians, engineers, and practical telegraphers. Meeting a friend of mine, an electrician, and who, by the way, is also a great mathematician, and, like all of his class, inclined to be very exact in his statements, I exclaimed, in all the warmth and exuberance of feeling engendered by so great an event, —
“ Is n’t it glorious, this idea of being able to send our lightning across the ocean, and to talk with London and Paris as readily as we do with New Pork and New Orleans ? ”
“ It is, indeed,” responded my friend, with equal enthusiasm ; " my hopes are more than realized by this wonderful achievement.”
“ Hopes realized ! ” exclaimed I. “ Why, I did n't consider there was one chance in a thousand of success, — did you ? ”
“ Why, yes,” replied my exact mathematical friend ; “ I did n’t think the chances so much against the success of the enterprise as that. From the deductions which I drew from a very careful examination of all the facts I could obtain, I concluded that the chances of absolute failure were about ninety-seven and a half per cent. ! ”
For many of the facts contained in this article I am indebted to the very clear and able address delivered by Mr. Cyrus W. Field before the American Geographical and Statistical Society, at Clinton Hall, New York, in May last, upon the prospects of the Atlantic telegraph.
At the start, of course, every one was very ignorant of the work to be done in establishing a telegraph across the ocean. Submarine telegraphy was in its infancy, and aërial telegraphy had scarcely outgrown its swaddling-clothes. We had to grope our way in the dark. It was only by repeated experiments and repeated failures that we were able to find out all the conditions of success.
The Atlantic telegraph, it is said by some, was a failure. Well, if it were so, replies Mr. Field, I should say (as is said of many a man, that he did more by his death than by his life) that even in its failure it has been of immense benefit to the science of the world, for it has been the great experimenting cable. No electrician ever had so long a line to work upon before: and hence the science of submarine telegraphy never made such rapid progress as after that great experiment. In fact, all cables that have since been laid, where the managers availed themselves of the knowledge and experience obtained by the Atlantic cable, have been perfectly successful. All these triumphs over the sea are greatly indebted to the bold attempt to cross the Atlantic made four years ago.
The first Atlantic cable, therefore, has accomplished a great work in deep-sea telegraphy, a branch of the art but little known before. In one sense it was a failure. In another it was a brilliant success. Despite every disadvantage, it was laid across the ocean ; it was stretched from shore to shore ; and for three weeks it continued to operate, — a time long enough to settle forever the scientific question whether it was possible to communicate between two continents so far apart. This was the work of the first Atlantic telegraph ; and if it lies silent at the bottom of the ocean till the destruction of the globe, it has done enough for the science of the world and the benefit of mankind to entitle it to be held in honored and blessed memory.
Now, as to the prospect of success in another attempt to lay a telegraph across the ocean. The most erroneous opinions prevail as to the difficulties of laying submarine telegraphs in general, and securing them against injury. It is commonly supposed that the number of failures is much greater than of successes; whereas the fact is, that the later attempts, where made with proper care, have been almost uniformly successful. In proof of this I will refer to the printed “ List of all the Submarine Telegraph-Cables manufactured and laid down by Messrs. Glass, Elliot, & Co., of London,” from which it appears that within the space of eight years, from 1854 to 1862, they have manufactured and laid down twenty-five different cables, among which arc included three of the longest lines connecting England with the Continent,— namely, from England to Holland, 140 miles, to Hanover, 280 miles, and to Denmark, 368 miles, — and the principal lines in the Mediterranean, — as from Italy to Corsica and thence to Toulon, from Malta to Sicily, and from Corfu to Otranto, and besides these, the two chief of all, that from France to Algiers, 520 miles, laid in 1860, and the other, laid only last year, from Malta to Alexandria, 1,535 miles! All together the lines laid by these manufacturers comprise a total of 3,739 miles ; and though some have been lying at the bottom of the sea and working for eight years, each one of them is at this hour in as perfect condition as on the day it was laid down, with the exception of the two short lines laid in shallow water along the shore between Liverpool and Holyhead, 25 miles, and from Prince Edward’s Island to New Brunswick, 11 miles; the latter of which was broken by a ship’s anchor, and the former by the anchor of the Royal Charter during the gale in which she was wrecked, both of which can be easily repaired.
Where failures have occurred in submarine telegraphs, the causes are now well understood and easily to be avoided. Thus with the first Atlantic cable, its defects have all been carefully investigated by scientific men, and may be easily guarded against. When this cable was in process of manufacture in the factory of Messrs. Glass, Elliot, & Co., in Greenwich, near London, it was coiled in four large vats, and there left exposed, day after day, to the heat of a summer sun, which was intensified by the tarred coating of the cable to one hundred and twenty degrees. This went on, day after day, with the knowledge of the engineer and electrician of the company, although the directors had given explicit orders that sheds should be erected over the vats to prevent the possibility of such an occurrence. As might have been foreseen, the gutta-percha was melted, so that the conductor which it was desired to insulate was so twisted by the coils that it was left quite bare in numberless places, thus weakening, and eventually, when the cable was submerged, destroying the insulation. The injury was partially discovered before the cable was taken out of the factory at Greenwich, and a length of about thirty miles was cut out and condemned. This, however, did not wholly remedy the difficulty, for the defective insulation became frequently and painfully apparent while the cable was being submerged. Still further evidence of its imperfect condition was afforded when it came to be cut up for charms and trinkets.
The first cable was, to a great extent, an experiment, — a leap in the dark. Its material and construction were as good as the state of knowledge at that time provided, and in many respects not unsuitable ; but the company could not avail itself, at that time, of the instruments or apparatus for testing its conducting power and insulation, in the manner since pointed out by experience. The effects of temperature, as we have seen, were not provided for. The vast differences in the conducting power of copper were discovered only by means of that cable, when made. The mathematical law whereby the proportions of insulation to conduction are determined had not been fully investigated ; and it was even argued by some of the pretended electricians in the employ of the company, that, the smaller the conductor, the more rapidly the current could pass through it. No mode of protecting the external sheath from oxidation had then been discovered ; and the kind of machinery' necessary for submerging cables in deep water could only be theoretically assumed.
Looking back to that period, and granting that there was too much haste in the preparations, and that other mistakes were committed which could now be foreseen and avoided, it is not too much to say, that, if that cable could be laid and worked, as was done, after one failure in 1857, and the consequent uncoiling and storage of it in an exposed situation, and after three attempts in 1858, under the most fearful circumstances as to weather, it would he an easy task to lay a cable constructed and submerged by the light of present experience.
The above cuts, representing sections of the cable laid in 1858 and the proposed new cable, will serve to show the difference between the two, and the immense superiority of the latter over the former. In the old Atlantic cable the copper conducting-wire weighed but ninety-three pounds to the mile, while in the new cable it weighs five hundred and ten pounds to the mile, or more than five times as much. Now the size, or diameter, of a telegraphic conductor is just as important an item, in determining the strength of current which can be maintained upon it with a given amount of battery-force, as the length of the conductor. To produce the effects by which the messages are expressed at the end of a telegraphic wire or cable, it is necessary that the electric current should have a certain intensity or strength. Now the intensity of the current transmitted by a given voltaic battery along a given line of wire will decrease, other things being the same, in the same proportion as the length of the wire increases. Thus, if the wire be continued for ten miles, the current will have twice the intensity which it would have, if the wire had been extended to a distance of twenty miles. It is evident, therefore, that the wire may be continued to such a length that the current will no longer have sufficient intensity to produce at the station to which the despatch is transmitted those effects by which the language of the despatch is signified. But the intensity of the current transmitted by a given voltaic battery upon a wire of given length will be increased in the same proportion as the area of the section of the wire is augmented. Thus, if the diameter of the wire be doubled, the area of its section being increased in a fourfold proportion, the intensity of the current transmitted along the wire will be increased in the same ratio. The intensity of the current may also be augmented by increasing the number of pairs of the generating plates or cylinders composing the galvanic battery.
All electrical terms are arbitrary, and necessarily unintelligible to the general reader. I shall, therefore, use them as sparingly as possible, and endeavor to make myself clearly understood by explaining those which I do use.
All telegraphic conductors offer a certain resistance to the passage of an electric current, and the amount of this resistance is proportional to the length of the conductor, and inversely to its size. In order to overcome this resistance, it is necessary to increase the number of the cells in the battery, and thus obtain a fluid of greater force or intensity.
On aërial telegraph-lines this increase in the intensity of the battery occasions no particular inconvenience, other than by tending to the more rapid destruction of the small copper coils, or helices, employed ; but upon submarine lines it has the effect of increasing the static electricity, or electricity of tension, which accumulates along the surface of the gutta-percha covering of the conducting-wire, in the same manner as static electricity accumulates on the surface of glass, or of a stick of sealing-wax, by rubbing it with a piece of cloth. The use of submarine or of subterranean conductors occasions, from the above cause, a small retardation in the velocity of the transmitted electricity. This retardation is not due to the length of the path which the electric current has to traverse, since it does not take place with a conductor, equally long, insulated in the air; but it arises from a static reaction, caused by the passage of an intense current through a conductor well insulated, but surrounded outside its insulating coating by a conducting body, such as sea-water or moist ground, or even by the metallic envelope of iron wires placed in communication with the ground. When this conductor is presented to one of the poles of a battery, the other pole of which communicates with the ground, it becomes charged with static electricity, like the coating of a Leydenjar,—electricity which is capable of giving rise to a discharge-current, even after the voltaic current has ceased to be transmitted. Volta showed in one of his beautiful experiments, that, in putting one of the ends of his pile in communication with the earth, and the other with a non-insulated Leyden-jar, the jar was charged in an instant of time to a degree proportional to the force of the pile. At the same time an instantaneous current was observed in the conductor between the pile and the jar, which had all the properties of an ordinary current. Now it is evident that the subaqueous wire with its insulating covering may be assimilated exactly to an immense Leyden-jar. The glass of the jar represents the gutta-percha; the internal coating is the surface of the copper wire; the external coating is the surrounding metallic envelope and water. To form an idea of the capacity of this new kind of battery, we have only to remember that the surface of the wire is equal to fourteen square yards per mile. Bringing such a wire into communication by one of its ends with a battery, of which the opposite pole is in contact with the earth, whilst the other extremity of the wire is insulated, must cause the wire to take a charge of the same character and tension as that of the pole of the battery touched by it.
These currents of static induction are proportional in intensity to the force of the battery and the length of the wire, whilst an inverse relation is true as regards the length of the conductor with the ordinary voltaic current.
Professor Wheatstone proved, by actual experiment, that a continuous current may be maintained in the circuit of the long wire of an electric cable, of which one of the ends is insulated, whilst the other communicates with one of the poles of a battery, whose other pole is connceed with the ground. This current he considers due to the uniform and continual dispersion of the statical electricity with which the wire is charged along its whole length.
It was mainly owing to the retardation from this cause that communication through the Atlantic cable was so exceedingly slow and difficult.
I will now endeavor to show why the new cable will not be liable to this difficulty, to anything like the same extent.
I have alluded to the resistance offered by the conductor of a telegraph-cable to the passage of an electric current, and to the retardation of this current by static induction. The terms retardation and resistance are not considered technically synonymous, but are intended, as electrical terms, to designate two very different forces. The resistance of a wire, as we have seen above, is proportional to its length, and inversely to its diameter. It is overcome by increasing the number of cells in the battery, or, in other words, by increasing the intensity or force of the current. The retardation in a telegraphic cable, on the contrary, is proportional to the length of the conductingwire and the intensity of the battery. In the former case, by increasing the electrical force you overcome the resistance; while in the latter, by augmenting the electrical force you increase the retardation.
From the foregoing law it will be seen that there are two ways of lessening the resistance upon telegraphic conductors,— one by reducing the length, and the other by increasing the area of the section of the conducting-wire. Now, as already remarked, the copper conducting-wire in the old cable weighed but ninety-three pounds to the mile, while in the new cable it weighs five hundred and ten pounds to the mile, or more than five times as much. If, then, by comparison, we estimate the resistance in the old Atlantic cable to have been equal to two thousand miles of ordinary telegraph-wire, the increased size of the conducting-wire of the new cable reduces the resistance to one-fifth that distance, or four hundred miles. And while it required two hundred cells of battery to produce intensity sufficient to work over the two thousand miles of resistance in the old cable, it will require but one-fifth as much, or forty cells, to overcome the four hundred miles of resistance in the new cable. The retardation which resulted from the intense current generated by two hundred cells will be also proportionately reduced in the comparatively small battery of forty cells. Thus we perceive, that, while the length of the cable is, electrically and practically, reduced to one-fifth of its former length, the retardation of the current is also decreased in the same proportion. Therefore, if, with the old cable, three words per minute could be transmitted, with the new cable we shall be able to transmit five times as many, or fifteen words per minute. This is not equal to our Morse system on the land-lines, which will signal at the rate of thirty-five words per minute, still less to the printing system, which can signal at the rate of fifty words per minute; but, even at this rate, the cable would be enabled to transmit in twenty-four hours one thousand despatches containing an average of twenty words apiece. Mr. Field, however, claims for the cable a speed of only twelve words per minute, which would reduce the number of despatches of twenty words each that could be transmitted in twenty-four hours to eight hundred and sixty-four. "Me will suppose, however, that the cable transmits only five hundred telegrams per day ; this number, at ten dollars per message, would give an income of five thousand dollars per diem, or one million five hundred and sixty-five thousand dollars per annum. Quite a handsome revenue on an outlay of about one million of dollars !
The only instrument which could be used successfully in signalling through the old cable was one of peculiar construction, called the Marine Galvanometer. In this instrument, momentum and inertia are almost wholly avoided by the use of a needle weighing only one and a half grains, combined with a mirror reflecting a ray of light, which indicates deflections with great accuracy. By this means a gradually increasing or decreasing current is at each instant indicated at its due strength. Thus, when this galvanometer is placed as the receiving-instrument at the end of a long submarine cable, the movement of the spot of light, consequent on the completion of a circuit through the battery, cable, and earth, can be so observed as to furnish a curve representing very accurately the arrival of an electric current. Lines representing successive signals at various speeds can also be obtained, and, by means of a metronome, dots and dashes can be sent with nearly perfect regularity by an ordinary Morse key, and the corresponding changes in the current at the receiving end of the cable accurately observed.
A system of arbitrary characters, similar to those used upon the Morse telegraph, was employed, and the letter to be indicated was determined by the number of oscillations of the needle, as well as by the length of time during which the needle remained in one place. The operator, who watched the reflection of the deflected needle in the mirror, held a key in his hand communicating with a local instrument in the office, which he pressed down or raised, according to the deflection of the needle; and another operator deciphered the characters thus produced upon the paper. This mode of telegraphing was, of necessity, very slow, and it will not surprise the reader that the fastest rate of speed over the cable did not exceed three words per minute. Still, had the old cable continued in operation a few months longer, experience and practice would have enabled the operator to transmit and receive with very much greater facility. On our land-lines, operators of long experience acquire a dexterity which enables them not only to transmit and receive telegrams with wonderful rapidity, but to work the instruments during storms, when those of less experience would be unable to receive a dot. There is no occupation in which skill and experience are more necessary to success than in that of telegraphing, and at the time the Atlantic cable was laid no experience had been obtained upon similar lines, or with the instruments employed. Now, however, the company can avail itself of experienced operators from lines of nearly equal length, and who will require no time for experimenting, but may commence operations as soon as the two ends of the cable are landed upon the shores of Europe and America.
In the old cable the copper wire was covered but three times with gutta-percha, while in the new it is covered four times with the purest gutta-percha and four times with Chatterton’s patent compound, by which the cable is rendered absolutely impenetrable to water. The old cable was covered with eighteen strands of small iron wire, which, as they had no other covering, were directly exposed to the action of the water. The new is covered with thirteen strands, each strand consisting of three wires of the best quality, and covered with gutta-percha, to render it indestructible in salt water. By this new construction, it has double the strength of the old cable, at the same time that it is lighter in the water, a very important matter in laying it across the ocean.
The risk of loss in laying the new cable would be very much diminished by the fact that it would be of such strength, that, even if broken, it could be recovered, as has been done in the Mediterranean ; and besides, the principal and most expensive materials, copper and gutta-percha, being indestructible, would have at all times a market value.
Other routes to Europe have been proposed, and have been at times quite popular, the most feasible of which are those viâ Behring’s Straits, or the Aleutian Islands, and viâ Labrador, Greenland, Iceland, and the Faroe Isles.
To the route viâ Behring’s Straits there are several grave objections. The distance from New York to London by a route crossing the three continents of America, Asia, and Europe, is about eighteen thousand miles, or more than nine times as great as that from Newfoundland to Ireland. Of course, the mere cost of constructing a continuous telegraph threequarters of the distance around the globe, and of maintaining the hundreds of stations that would be necessary over such a length of land-lines, would be enormous. But even that is not the chief difficulty. A line which should traverse the whole breadth of Siberia would encounter wellnigh insuperable obstacles in the country itself, as it would have to pass over mountains and across deserts ; while, as it turned north to Kamtschatka, it would come into a region of frightful cold, where winter reigns the greater part of the year. Of this whole country a large part is not only utterly uncivilized, but uninhabited, and portions which are occupied are held by savage and warlike tribes.
Of the Greenland route, Doctor Hayes, the well-known Arctic traveller, expresses himself in the most decided manner, that it is wholly impracticable. He says it must be obvious that the ice which hugs the Greenland coast will prevent a cable, if laid, from remaining in continuity for any length of time. Doctor Wallich, naturalist attached to Sir Leopold McClintock’s expedition to survey the Northern route, considers it impracticable on account of the volcanic nature of the bottom of the sea near Iceland, and the ridges of rock and the immense icebergs near Greenland.
The main argument in favor of this route, in preference to the more direct one across the Atlantic, is, that it would be impossible to work in one continuous circuit a line so long as that from Newfoundland to Ireland. This would seem to be answered sufficiently by the success of the old Atlantic cable. But it is alleged that it worked slowly and with difficulty, which is true, and hence it is thought that the distance would be at least a very great obstacle. But we have shown, that, practically, by the increased size of the conducting-wire, the new cable has been reduced in length four-fifths, and will work five times as fast as the old one. The cable extending from Malta to Alexandria is fifteen hundred and thirty-five miles long, and the whole of this line can be worked through without relay or repetition in a satisfactory manner, as regards both its scientific and commercial results, and with remarkably low battery-power. The Gutta-Percha Company, which made the core of this cable, says that a suitably made and insulated telegraph-conductor, laid intact between Ireland and Newfoundland, can be worked efficiently, both in a commercial and scientific sense, and they are prepared to guaranty the efficient and satisfactory working of a line of the length of the Atlantic cable as manufactured by themselves, and submerged and maintained in that state.
It can be shown by the testimony and experience of those most eminent in the science and practice of oceanic telegraphy, that neither length of distance, within the limits with which the Atlantic Company has to deal, nor depth of water, is any insuperable impediment to efficient communication by such improved conductors of electricity as are now proposed to be laid down. All those who are best able to form a sound opinion, from long-continued experimental researches on this particular point, are willing to pledge their judgment, that, on such a length of line as that between Ireland and Newfoundland, and with such a cable and such improved instruments as are now at command, not less than twelve words per minute could be transmitted from shore to shore, and that this may be done with greatly diminished battery-power as compared with that formerly used.
I think I have shown by facts, and not theory merely, that the Atlantic cable can and will be successfully laid down and worked, thus supplying the long-needed link between the three hundred thousand miles of electric telegraph already in operation on the opposite shores of the Atlantic.
There are many of our people who are inclined to look coldly upon this enterprise, from a conviction that It would give Great Britain an undue advantage over us in case war should occur between the two countries, and I confess to having entertained the same views; but the case is so well put by Mr. Field, in his address before the American Geographical Society, as, in my judgment, to relieve every apprehension upon this point.
The relative geographical position of the two countries cannot be changed. It so happens, that the two points on the opposite sides of the Atlantic nearest to each other, and which are therefore the natural termini of an ocean-telegraph, are both in British territory. Of course, the Government which holds both ends can control the use of the telegraph, or stop it altogether. It has the power, and the only check upon the abuse of that power must be by a treaty, made beforehand. Shall we refuse to aid in constructing the line, for fear that England, in the exasperation of a war, would disregard any treaty stipulations in reference to its use ? Then we throw away our only security. For, suppose a war to break out to-morrow, the first step of England would be to lay a cable herself, for her own sole and exclusive benefit. Then she would not only have the control, but would be unrestrained by any treaty-obligations binding her to respect the neutrality of the telegraph. We should then find this great medium of communication between the two hemispheres, which we might have made, if not an ally, at least a neutral, turned into a powerful antagonist. Would it not, therefore, be better that such a line of telegraph should be constructed by the joint efforts of both countries, and be guarded by treaty-stipulations, so that it might be placed, as far as possible, under the protection of the faith of nations, and of the honor of the civilized world ?
Mr. Field says, that, in the negotiations on tins subject, Great Britain has never shown the slightest wish to take advantage of its geographical position to exact special privileges, or a desire to appropriate any advantages which it was not willing to concede equally to the United States.
Should not the Atlantic telegraph, if laid down under the conditions proposed by the Company, instead of being a cause of apprehension, in case of war, be rather looked upon with favor, as tending to lessen the risk of war between the United States and all European countries, affording, as it would, facilities for the prompt interchange of notes between the Government of the United States and those of the various nations on the other side of the Atlantic, whenever any misunderstanding should unhappily arise ?
Let us, then, throw aside all feeling of apprehension from this cause, and be prepared to hail, with the same enthusiasm we experienced in 1858 at the laying of the old, the completion of the new Atlantic cable.