Introduction: The late 1850s was a period of some controversy in the cable industry. With the prospect of large profits, arguments had arisen about who had priority in early experiments with laying cables, and the failure of the 1858 Atlantic cable had set other companies and individuals in pursuit of alternative routes, materials, and techniques for this important project.
One early experimenter was Charles West, who had contemplated an ocean submarine cable as early as 1838. West was experimenting with underwater insulation from then until 1841, when he settled on india-rubber as the best possible material, and he continued to promote it for many years. See this article by Steven Roberts on early British domestic cables for more information on West’s work in the 1840s.
In 1859 West was publisher (and unsigned author) of The Story of My Life by “the Submarine Telegraph” (written as if the cable itself were the narrator). Bern Dibner describes this book as “an anonymous, biting review of the early history of submarine telegraphy.” West describes in the book how others took credit for what he believed to have been his ideas, and is scathing about every aspect of the Atlantic telegraph expeditions of 1857 and 1858.
Perhaps not coincidentally, West had been associated for many years with S.W. Silver & Company, a well-established firm making many commercial and domestic products of india rubber, including some insulated wires and cables. Building on earlier work with india-rubber, the firm had a new method of treating and applying “caoutchouc” (another name for natural rubber) as cable insulation.
The 14-page pamphlet whose text is reproduced below is a report of the proceedings at a meeting on Friday May 27th 1859 at Silver’s works in North Woolwich, where Charles West related his history of insulating cables with india-rubber and demonstrated the caoutchouc insulation and its applications. This was evidently one of a series of meetings on the subject, and the presentation makes it clear that Silver intended to expand its manufacturing to include submarine cables, whose gutta percha insulation was at that time a virtual monopoly of the Gutta Percha Company.
Present at the meeting were many of the cable industry’s leading figures, who took both pro and con positions on the new insulation, which led to some interesting debates. The report notes that samples of copper wire coated with “Patent Caoutchouc Insulator” were passed out at the meeting; one is shown here, and in more detail below. It seems likely that quite a few these samples were made and distributed at the time, but this is the only one known at present.
Contrary to West’s arguments for the superiority of this insulation, tests in actual use showed that while it was a good insulator, india-rubber was not as durable as gutta percha. For example, although Wildman Whitehouse’s test results quoted in West’s presentation are positive for india rubber, in Whitehouse’s December 1859 testimony before the Joint Committee investigating the failure of the Atlantic cable he noted that the material had deteriorated quite badly on samples of Silver’s india-rubber insulation which he had examined. Gutta percha continued to be the main material used to insulate undersea cables until the advent of polyethylene in the 1940s, and Silver’s patent caoutchouc seems to have had little use.
In 1863 S.W. Silver formed Silver’s India Rubber Works & Telegraph Cable Company, Limited. In 1864 Charles Hancock, formerly of the West Ham Gutta Percha Co, joined the company, bringing with him his patents and knowledge of gutta percha, and the name was changed to the India Rubber, Gutta Percha and Telegraph Works Company Ltd., which tells its own story. The IRGP, or the Silvertown Company as it was often called, made its first submarine cable in 1865 and many more subsequently, eventually owning and operating four cable ships, although the company’s cable business was in decline by the early 1900s.
Samples of gutta percha insulated cable recovered after over a hundred years at the bottom of the ocean have shown the copper conductor to be in as good condition as the day they the cable was laid, while I know of no similar samples of recovered india rubber insulated cable.
Note: Two other pamphlets on this subject are recorded in the Wheeler Gift catalog, but these have not yet been consulted:
5534. Silver, S.W. & Co. Patent caoutchouc telegraph insulator. 11 pp. 8vo. London, 1859
5534a. (Another edition.) 9 pp. 8vo. London, 1860
An 8-page pamphlet on the same subject (undated, but late 1860 by dates on the correspondence included in its appendix), titled Insulation for Submarine Telegraphy, is in the library of the Institution of Civil Engineers. It is not known whether this is the same as the 9-page pamphlet listed above. This edition includes a report from the Mining Journal on a similar meeting held on Saturday March 12th 1859, a somewhat abbreviated version of the report of the meeting of May 1859 as published in the 14-page pamphlet, and extracts of correspondence to S.W. Silver from industry figures. The portions of this edition which do not duplicate the content of the 1859 text are also reproduced here.
Charles West continued his campaign against gutta percha; in 1861 he presented a lecture on the subject to the Royal United Service Institution, established in London in 1831 for “military and security thinking”. He again recycled verbatim much of the material from the pamphlets below, and reference is made during the question period to yet another presentation at the “Society of Civil Engineers” shortly before.
Acknowledgments: The texts reproduced below from the 1859 14-page pamphlet and the 1860 8-page pamphlet are taken respectively from the copies at the Dibner Library of the History of Science and Technology at the Smithsonian Institution, and the Library of the Institution of Civil Engineers in London. My thanks to the ever-helpful Kirsten van der Veen, Technical Information Specialist at the Dibner Library, and Debra Francis at the ICE Library.
PROCEEDINGS OF THE MEETING
HELD AT THE
SILVERTOWN INDIA RUBBER WORKS,
FOR THE PURPOSE OF DISCUSSING THE MERITS OF
S.W. SILVER & CO.’S
PATENT CAOUTCHOUC INSULATOR,
MAY 27th, 1859.
John K. Chapman and Company, 5, Shoe Lane,
and Peterborough Court, Fleet Street
THE PATENT CAOUTCHOUC TELEGRAPHIC INSULATOR.
Report of the Meeting at Messrs. Silver and Co.’s Caoutchouc Insulator Wire Works, Silvertown, North Woolwich, on Friday, May 27th, 1859, held for the purpose of witnessing experiments and discussing the merits of India rubber as a medium of insulation.
Amongst the gentlemen present were:—The Rev. J. Barlow, F.R.S., M.A., F.L.S., V.P., and Secretary, Royal Institution, Rev. W. Mitchell, Rev. H. Douglas, Captain Boxer, F.R.S., R.A., Superintendent, Royal Laboratories, Woolwich, Captain Haultain, R.A., Major Rhodes, Lieutenant Lamb, Thomas Graham, F.R.S., M.A.D.C.L., Master Mint, F.G.S., &c., James Glaisher, F.R.A.S., Edward Frankland, F.R.S., Ph.D. Lecturer on Chemistry, St. Bartholomew’s Hospital, William Fairbairn, F.R.S., W.C. Mylne, F.R.S., F.R.A.S., W. Gravatt, F.R.S., C. Wheatstone, F.R.S., C. R. Weld, Secretary and Librarian, Royal Society, Professor Goodeve, Professor Morris, Professor Weil, F.A. Abell, Chemist, Royal Arsenal, Woolwich, C.V. Walker, F.R.S., F.R.A.S., Edwin Clark, Latimer Clark, F.C. Webb, W.H. Winter, L.W. Courtenay, J. Muirhead, J. Meadows White, S. Walcott, S.A Varley, C.F. Varley, C.J. Varley, C.W. Siemens, C.J. Wollaston, Henry Sach, Edward Highton, J. Levick, W.H. Smith, F.N. Gisborne, J.A. Longridge, G.S. Walters, Government Agent, South Australia, James Meaburn, Deputy Harbour Master, Greenwich, John Savory, C.V. De Sauty, and several other gentlemen interested in scientific pursuits.
Arthur Mills, Esq., M.P., having taken the chair, opened the business of the meeting by saying:—Gentlemen, I have been requested by the Messrs. Silver to take the chair on this occasion, not to make a speech, but to hear one made; and, therefore, I will simply call on Mr. West to read the paper I have in my hand, which I think will be most agreeable to nil present, and the best introduction to the experiments you are about to see. I do not possess any detailed knowledge of scientific pursuits: I came here not to teach, but to learn—that is the sole object I have in view. I do not come here to attempt to teach those who are present; but simply as one amongst the ranks of these who are willing to learn the effect of any new experiments that have been made with regard to this most important and most interesting matter. I feel at such a moment as this, that any man, or body of men, amongst the masses who can contribute any new offering on the subject of telegraphic communication, ought to he considered as a benefactor, or benefactors, to the nation. (Hear, hear). We have all of us felt, more or less, extreme disappointment at the failure of the Atlantic Submarine Cable, and have watched, with intense interest, all experiments that have hitherto been made, both in the Mediterranean and the British Channel; in fact, throughout the world submarine telegraphy is becoming a subject of considerable interest; and I only express, I am sure, the feelings of all present, when I say, all are aware that any contribution to this stock of knowledge will be in the highest degree acceptable. There is one paragraph in Mr. West’s paper, which will be read to you presently, which bears very minutely and very pertinently on the question; it is this —speaking of experiments made in past times and recently—of “the distinction between India rubber and gutta percha, as regards insulation: for instance, even now, as in the oldest time, in consequence of India rubber not becoming plastic at a low temperature, it is impossible to draw it on the wire, like maccaroni or gutta percha; its first stage of manipulation is in winding it spirally round the wire, according to the sample I now show you. By this method, although the wire is in the centre of the insulating material, yet the material itself is not rendered homogeneous, and the want of cohesion in the overlapping renders it liable to the penetration of water, and its thus becoming useless. I have hitherto tried to remedy this by the exterior application of solvents; and have even used India rubber itself, in solution, bound on by tape, but all to no purpose; for although successful in some instances, the result was uncertain, and not to be depended on. Now, the improvements in the manipulation consist in rendering that which was not even cohesive, perfectly solid and homogeneous, and this by means not in the least injurious to the India rubber. In this state neither heat nor cold will detrimentally affect its homogeneous principle, and it will be able to transmit the electric fluid, if properly manipulated, without any lateral loss, and thereby render the use of batteries of great and extraordinary power quite unnecessary.”
This is most material as affecting our dependencies in the East. Some of us know it perhaps by personal experience, and others by common report, that there everything is subject to extreme heat, and the experiments about to be made will show that the material now presented is more impenetrable to atmospheric influence than any that yet has been discovered. As I have already said, I will not detain you by giving a lecture on the subject—it is one I do not understand; but I feel in common with you all, this is a subject to which all these who contribute successfully are worthy of the highest regard. It is an old and trite saying, that we are the citizens of an empire on which the sum sever sets; an empire which certainly embraces every variety of climate as well as almost every variety of race. Happily, we have come to a time in which our connection with these dependencies is regarded not as a mere matter of keeping up our military defences and our naval position. I recollect a very distinguished senator, whom I had the pleasure of meeting on several occasions when I visited the American continent—I mean Mr. Daniel Webster—speaking of England, he said the power of Rome and its glory was not to be compared with hers. The surface of the globe was dotted with her military posts, so that the beat of the morning drum went with the sun in one unbroken sound of military music. We do not now dwell on the military glories to arise from our military power in our dependencies, but we hope to attach them to us by more enduring causes; we are invited to approach them by glories—not ‘fanned by conquest’s crimson flag’-but by those by which we hope to diffuse civilization and christianity to the utmost corners of the world. (Cheers). For the purpose of promoting these high objects, not only in our various dependencies, but even in the mother country, for the performance of our duties both as citizens, as christians, I know no material means more likely—under God’s blessing—to attain these ends than the perfection of the objects of Messrs. Silver and Mr. West. I will conclude by calling on Mr. West to read his paper, which I am sure will prove a valuable contribution.
Mr. West then read the following paper:—I should not, without considerable hesitation, presume to call your attention to a subject of so much importance to Submarine Telegraphy as the one I am about to submit to your notice upon the present occasion, unless I had given it that serious consideration which has enabled me to understand it thoroughly, and to arrive at conclusions founded on correct, and not on erroneous, data.
It must be well known to all present, that the first principal requisite for the success of any telegraph, either land or oceanic, is in the perfection of its insulation. Without perfect insulation, in either case, the result must be—failure. By land, the insulation is attained by the metallic wires, without any covering, being suspended on glass or earthenware insulators placed on posts. These are seen everywhere throughout the country wherever n line of railway traverses, and are now so familiar to the public that they have ceased even to excite curiosity or attention, being regarded as one of the established and ordinary facts of the day.
But with regard to the insulation for submarine purposes the case is widely different; the difficulties are much greater, as it is necessary that the whole length of the wire should be incased in a sheathing utterly impervious to the water, under any pressure, or under any circumstances save those of injury by violence; and that the current of electricity sent through this wire should be transmitted in its entirety, without reference to distance, with no loss whatever, either from the imperfection of the insulating material itself, or from any fault in the manipulation in placing it round the wire.
It was supposed when gutta percha was first introduced, that this was a material which would meet all these requirements. Time, however, has shown that such is not the case, and that in the most essential points, especially as regards insulation, and the durability of insulation, it has been found wanting. Hence it is, that in consequence of the numerous failures that have occurred, and the vast amount of capital that has been lost, by the use of gutta percha, those who are engaged in telegraphic pursuits are desirous of procuring some efficient substitute for it.
It is with the view of supplying the demand that now exists for a better and more reliable means for effecting sub-oceanic telegraphic communication, that the Messrs. Silver have adopted an improved system of insulating with India rubber; I say an improved system, not a new one, because the material was originally used for the purposes of insulation long before gutta percha was known in this country, and is the same which I am now about to introduce to your notice—India rubber. The improvement is in the manipulation and application of the gum, and not the material itself.
It is many years ago since I commenced the use of India rubber for insulating wires. In the year 1838—twenty-one years ago—upon being appointed by the Government of the day, on the outbreak of the Canadian Rebellion, to position which involved among other duties the transmission of the earliest intelligence from the seat of insurrection, it was then that in turning my attention to every possible means by which I could most effectually perform this duty, I thought of establishing a telegraphic communication between this country and Canada. The disturbances in Canada were happily but short-lived, and the necessity no longer existing, I abandoned my embryo project of establishing electric communication to Canada until a more seasonable opportunity, as I was well aware that even when land telegraphy had only just been mooted—but not developed, a project of such a gigantic nature would then have been deemed impracticable. I resolved, however, to try if I could not, in the first place, successfully connect countries more immediately adjacent to each other, and separated only by narrow seas. I considered Dover and Calais as the most appropriate places for my first essay; and then I forthwith commenced the attempt to insulate the wires for that purpose. This, however, was not the work of a day, but occupied some considerable time, during which period I tried almost every description of bitumenous, resinous, oleaginous, and other substances; sometimes singly, and at other times in combination, but all to no purpose; for as they dried and hardened upon the wire, they cracked upon bending it, and thus destroyed the insulation. At length I adopted India rubber for the covering, which I found to be not only the most eligible material, but in every way to answer the purpose, both with respect to insulation and flexibility. It must be borne in mind, that at this early period, 1841, gutta percha was unknown, and was not introduced into this country, and applied to the purposes of insulation, for several years after this date; although, if it had been extant at the time, I should have still used India rubber in preference, as I have ever considered it a much better material for insulating then that by which it was supplanted, and time has tended to strengthen me in that opinion.
Although I was ready with the wire in 1841, it was not until 1845 I was enabled to enter into any definite negociation to connect England and France; when, in conjunction with Captain Taylor, who was associated with me on that occasion, an arrangement was entered into that year with Messrs. Paxton,—now Sir Joseph, Charles Dickens, and other gentlemen, to lay down a cable for them across the channel, subject to the sanction of the British and French governments. The sanction of the former was obtained in three days, while that of the French government was not obtained until after a delay of three months, which proved a barrier to the carrying out of the undertaking at that period, in consequence of the gentlemen I have named having been compelled to make other arrangements to accomplish the object they had then in view.
I have adverted to this subject solely because it has especial reference, and is most pertinent, to the object of the present meeting. I had, during these negociations, commenced the construction of the cable intended for use between Dover and Calais, and having completed a sufficient portion of it, I resolved to give a practical demonstration of its capabilities. For this purpose I applied to the Lords of the Admiralty, requesting their sanction and co-operation to accomplish this, which was most promptly afforded me, and by which I was enabled to. carry out the desired experiments, first between H.M. ships Pique and Blake, and subsequently across Portsmouth Harbour. These experiments were made under the superintendence of Mr. Hay, the chemical referee and lecturer of the dockyard, and were most satisfactory in their results.
A portion of the insulated wire then tried was left in the hands of Mr. Hay, for future tests and experiments, and being desirous of submitting to you at this meeting every information I could obtain bearing upon the question of insulation, and the best material to he employed in effecting its successful attainment, I applied to Mr. Hay, soliciting he would furnish me with a small piece of the wire left with him, and the official reports, if any, he may have made at the time. Mr. Hay has kindly acceded to the first part of my request, but has referred me to the Lords Commissioners of the Admiralty for the procuration of the second. The following is the letter sent to me by that gentleman, with reference to my application:—
May 25th 1859,
Herewith I forward you a piece of the India rubber covered wire which formed a portion of that which was laid down experimentally under my superintendence (in accordance with directions I received from Admiral superintendent Sir Hyde Parker, to give every assistance), between H.M. ships Pique and Blake, and subsequently across the harbour, in 1846. The insulation was at that time considered by all who witnessed the experiments to be most satisfactory. Since that period I have used it as occasion required, and the insulation is now quite perfect, although my usage has been very rough: such as exposure to the sun, and frequent coiling, and straining on rough stones after use in the water. With respect to the reports you refer to, I must beg of you to make application to the Lords Commissioners of the Admiralty, who will, no doubt, if they are in existence, cause you to have copies of them.
I remain, dear Sir,
Your most obedient Servant,
William John Hay
C. West, Esq.
I find in calling your attention to this by no means unimportant matter that I have extended my paper beyond the limits I originally intended. I will, therefore, briefly refer to one or two points in connection with the subject immediately before us.
I have stated that the material adopted by the Messrs. Silver is by no means a new one, and, in fact, I have shown that to be the case in the observations I have made and the facts I have stated; and that the improvements consist in the manipulation and application of India rubber, not in the gum itself. For instance, even now, as in the olden time, in consequence of India rubber not becoming plastic at a low temperature, it is impossible to draw it on the wire like maccaroni or gutta percha, its first stage of manipulation is in winding it spirally round the wire, according to the sample I now show you. By this method, although the wire is in the centre of the insulating material, yet the material itself is not rendered homogeneous, and the want of cohesion in the overlapping renders it liable to the permeation of water, and its thus becoming useless. I have hitherto tried to remedy this by the exterior application of solvents, and have even used India rubber itself in solution bound on by tape, but all to no purpose; for although successful in some instances, the result was uncertain, and not to he depended on. Now the improvement in the manipulation consists in rendering that which was not even cohesive perfectly solid and homogeneous, and this by means not in the least injurious to the India rubber. In this state neither heat nor cold will detrimentally affect its homogeneous principle, and it will be able to transmit the electric field, if properly manipulated, without any lateral loss, and thereby render the use of batteries of great and extraordinary power quite unnecessary.
There are other matters of comparatively minor consideration, but in themselves important, connected with the new system, which I might touch upon, but the length to which I have already gone precludes further observation on my part.
Successes have been achieved by gutta percha, while, on the other hand, great losses have occurred. The successes have only been upon short lines, and where there has only been a comparatively unimportant outlay of capital; but the reverses have been upon long lines, and the injurious results of these failures are not only to he measured by the hundreds of thousands that have been literally thrown into the sea, but by the want of that which has become a necessity of civilisation in the means of a rapid intercommunication between nation and nation.
The object of the Messrs. Silver in the present instance is to invite public attention to their production, with a view to having the most searching investigation into its merits; not dogmatically putting it forth as a perfect invention, but seeking to elicit by the most open and unreserved exposition of its qualities, the truth with regard to its capabilities and the claims it would have, in consequence, on the public for support.
Mr. West went on to say.—In the paper which I have read, I have stated the most important feature in the present improvement in the application of India rubber, consists in its proper manipulation and preparation. In consequence of its not being easily affected by heat so as to become elastic, even at a high temperature, it is impossible to put it on a wire except by winding it spirally round. This is a sample—(holding it up) of India rubber after the first stage of manipulation; it is wound round by machinery, but not being cohesive, the water will permeate through the interstices of the over lapping; and, consequently, all insulation is destroyed. The mode hitherto adopted, although we have employed solvents, has been imperfect and anything but certain; but I have now adopted a more simple, more facile, and much more certain means of obtaining insulation; I employ a moist heat to render it not only cohesive, but a perfect solid tube. (Specimens were here handed round to the company.)
Patent Caoutchouc Insulator
S.W. Silver & Co.
Cornhill & Bishopsgate St. London
Works Silvertown Essex
Click through the image for a larger version,
which clearly shows the spiral wrapped insulation
Having shown the facility of manipulation, and the great degree of heat it will bear without loss of insulation, here I place a coil in water at a very high temperature of 180 degrees. This coil has been boiled,—I do not know how many times. The last time you were here it underwent the same operation, but gutta percha failed at a comparatively low temperature; however, to go to the material merits, when you know there are one hundred joins in fifty yards of the wire, not only of the India rubber, but the junction of the wire itself—a join at every half yard, the importance of this will be thoroughly understood in long lines, where you have occasion to make a number of joins in connecting the wire.
The wire was then tested, and the insulation found to be quite perfect.
The Chairman:—Do I understand you that this has been immersed in water at 180 degrees to see what the effect would be?
Mr. West:—This with 100 joins in fifty yards has been immersed in water at 180 degrees, with a battery power of 230 upon it. Now, I will shew you how the joins and insulations can be produced, in the event of any accident by which injury or damage is sustained.
The wire was then fractured.
Mr. Blake:—The India rubber has been taken off the wire, and every means of insulation destroyed, and you wish to show with what facility it can be renewed again?
Mr. West: Exactly so, and while the wire is being prepared, I will just advert to the subject I mentioned in the paper I have just read, that Mr. Hay, of the chemical department of Her Majesty’s Dockyard at Portsmouth, has forwarded me a small portion of wire that was laid down across the harbour in 1846, under his superintendence, between the ships Pique and Blake. He has had the wire constantly in use ever since, and he candidly writes to me that he has subjected it to something like tortures and unkind treatment; however, notwithstanding all this, here it is at the present time (producing it) after having been in use for upwards of thirteen years: (hear, hear).
The injury having been repaired, and the coil again placed in hot water, Mr. West resumed as follows:
You see, gentlemen, no real injury has been done to the wire, it is jointed now completely, and the insulation is perfectly restored: the simple cause of its becoming insulated is, that the India rubber is now cohesive; it is perfectly solid, homogeneous, and utterly impervious to water and air.
The Chairman:—There are other parts of the world besides our own—the American colonies for instance—who would like to know something about it, and it would be very satisfactory if gentlemen would ask questions and raise points that have not been alluded to, because the Messrs. Silver wish to have every light thrown upon the subject. So far as we are concerned we feel obliged by the experiments that have been made before us.
Mr. Glaisher; —I wish to know whether this applies to a single wire only, or a combination of wires? Gutta percha can be used in one wire or a dozen in combination.
Mr. West:—It may either be a single wire or a combination of wires formed into a group—you can do it either one way or the other. Mr. Chairman and gentlemen, I am very happy to have it my power to say that a communication has been made to me this moment by a practical gentleman, Mr. Varley, Electrician to the Electric Telegraph Company, who says he has subjected it to a practical test, and he finds for the purpose of insulation India rubber is far superior to—in fact, ten times better, than gutta percha. This statement comes from a practical authority, and it is highly gratifying to me to be able to make this communication.
Mr. Fairbairn:—May I ask what pressure, if any, your India rubber has been subjected to?
Mr. West:—I beg pardon, I ought to have directed your attention to that most important point. Hydraulic pressure has been applied to it by a gentleman who is not present—Mr. Whitehouse—who has stated that he applied a pressure of 15,000 lbs. to the inch, We have a hydraulic machine which I intended to have offered to your notice, so that you might see what pressure the wire would bear; but in putting it to the test, the machine gave way at 7,500 lbs. only. The test to which Mr. Whitehouse applied the wire by his machine, or the machine he used, stood the pressure of 15,000 lbs. to the inch, and then it burst. I beg this to be understood, that these experiments were not made in my presence; all I know is, that in the experiments made here the wire bore a pressure of 7,500 lbs., and the machine gave way, but the wire remained perfect.
Mr. Siemens:—I should like to know how long any of this wire has been submitted to the action of water.
Mr. West:—In reply to that question, I think I stated that so far back as 1846, a portion of the cable intended then to be laid down between Dover and Calais, was first submitted to experiments across Portsmouth harbour, between Her Majesty’s ships Pique and Blake.
Mr. Siemens:— But I mean the longest time it was exposed to water.
Mr. West:—There is a portion of India rubber cable laid down between Keyhaven and Hurst Castle, which forms part of the telegraph to the Isle of Wight. It was laid down in 1853, and is still working there. You will understand this cable was constructed under adverse circumstances, which I have endeavoured to explain to the meeting; it was not under the new principle which makes it become solid, and perfectly impermeable to water. Now, if this was manipulated under difficult circumstances, and has stood the test, how much more effective would it have been if manipulated under more favourable circumstances?
Mr. Fairbairn:—I know Mr. Whitehouse is a very careful man, and I accept the facts as stated by him. I am sorry, he is not present; but I want to know whether the cable has been subjected to any other pressure?
Mr. West:—The statement made to me by Mr. Whitehouse, that he got a pressure of 15,000 lbs. to the inch was viva voce; but, at all events, I have a letter front him, in which he states—”You will be delighted to hear that it stood the test of 1,000 atmospheres.”
Mr. Walker:—I may, perhaps, mention that, knowing Mr. Whitehouse, in a conversation I had with him, he told me in the test he made, that the apparatus blew up under a pressure of 1,200 or 1,300 atmospheres. The press broke under a strain of 15,000 lbs. without in any way affecting the caoutchouc covering, and that after the 1,000 atmospheres had been put upon it. The wire tested perfectly with a battery of 500 platinised oidon [???- silver? lead?] and zinc elements, using a galvanometer so delicate that a divergence could be obtained by rubbing one finger upon a zinc plate, and then bringing it in contact with one of the brass terminals, a finger also being upon the opposite terminal. On the same evening we tested some small balloons of India rubber; he filled one of them before me, and tried a very high pressure, and so far as the experiments were made, I have great pleasure in saying they were successful.
Mr. West:—Gentlemen, I have no hesitation in saying, whatever pressure you put this gum to, the electricity is not affected either one way or the other.
Mr. Siemens:—Occasionally, in deep water, the water penetrates the gutta percha, and if you make a hole, you can squeeze a drop out. I observe here one end of the India rubber coating does not attach itself close to the wire, but merely slips over it; it is, therefore, important to know whether there is any leakage by which the water may pass through and get to the joints. And now I am up, I should like to ask another question—because we are here as practical men—How much better is India rubber than gutta percha as an insulator? I should like to have some practical test. Mr. West tells us India rubber is better than gutta percha, and we know, as he stated, the first line laid down did not answer; however well coated the wire might be externally, after a lapse of time the water found its way through. I should like to know whether experiments have been made to test the relative insulating power of India rubber and gutta percha and in what proportions?
Mr. West:—I believe I can answer those two questions in one reply. The new method the Messrs. Silver are now adopting will remedy all those defects and deficiencies to which submarine cables have hitherto been open; and the reason it will do so is this: because it renders them solid and impervious to water. Subject India rubber to any pressure you think proper, and you will find it is a better insulator; try it by any experiment you like and you will find when a piece of India rubber becomes solidified it will always resist both air and water under any particular application of pressure. As to its insulating properties, it is superior to gutta percha in consequence of the nature of the gum. As to the nature of gutta percha, if you examine it with a microscope you will it porous, and perceive the germs of decay and decomposition contained within it; but if you examine India rubber thoroughly, you will find it free from these defects; the one gum is porous, the other is free from porosity, and consequently that which is free from porosity cannot allow any escape of fluid in passing through the water; therefore, I answer your question in saying, that every experiment that has been made since India rubber and gutta percha were known have tended to show the loss by leakage of the latter, and the correctness, as a conducting medium, of the former,
Mr. Varley:—When gutta percha was first introduced, I attended several experiments, and I found a great number of globular particles remained after it was dissolved. It is not the same with India rubber; that is not subject to globular particles.
Mr. West:—You are perfectly right.
Mr. Wollaston:—I see from the invitation that the Messrs. Silver wish this matter to be fully gone into on its merits. I personally do not wish to hold up or advocate any medium unless it be the best. My knowledge of the submarine cable began with the Dover and Calais line. Gutta percha was found fault with from this, amongst other causes, that when a certain strain was placed upon it it elongated the copper wire, and the strain being removed, the gutta percha buckled up the wire, and it came out through the sides of the gutta percha. I saw that myself, and I have specimens about me still, Now, India rubber being to a greater extent elastic; is there not great fear that that will occur more frequently, that the copper wire will become elongated when a strain is placed on the cable, that the elasticity of the India rubber will tend to compress the wire, and force it out through the sides of the India rubber? I think practice will show that is likely to be the case. If Mr. West had not talked of the defects of gutta percha, I should not have got up on this occasion; but being the first practically to use gutta percha between France and England, and finding the gutta percha as perfect as when it was first laid down—barring accidents-I do not think Mr. West should throw cold water on it. Where will any one find the temperature of the ocean above 96 degrees ? I assume it is not over 96; consequently, if gutta percha will stand a temperature of 96, what is the advantage of India rubber over it? I am afraid I am sowing the seeds of discord here where we have been so kindly received by Messrs. Silver; but I should not have spoken at all, if so great a slur had not been cast on gutta percha. I know it to have been under water for a length of time, and to be as perfect as when first laid down.
Mr. West:—I beg it to be understood that I am not the author of the calumnies against gutta percha. When gutta percha came in, India rubber was banished entirely, and I retired with my adopted child into silence and solitude; I never interfered with its success or non-success; it is only since complaints have been made by practical gentlemen acquainted with the subject, men of science, that I have presumed to utter a word, and I have done so courteously. Now, as to the excellence of India rubber as compared with gutta percha, it may be said you are either a libeller, or you have some correct data on which you found your statement; but I will ask gentlemen whether, in passing through the streets of London, they have not seen men dragging up large coils of wire which have been down only a few short years: and I will ask Mr. Wollaston himself—as he has been connected with the Dover and Calais line from its commencement, if he does not recollect that after eight or ten wires had been laid down at considerable expense from London to Dover—that after only two years’ service they were obliged to be taken up as useless and valueless, in consequence of decomposition?
Mr. Wollaston:—I alluded solely to gutta percha under water. When used on land, suspended in air, or sunk in the earth, it has been a failure far and wide. I never was an advocate for laying down gutta percha under, ground, and, what is more, I never will be.
Mr. West:—That is undoubtedly its character on land, but let us take it to sea and ascertain what it has done there. There is a gentleman not present who stands high in the practical world, a man of great experience, who assisted in laying down the Dutch cable between Orfordness and the Hague, who states that after it had been used a very short time, it was necessary, in consequence of lateral escapements, to use a high battery power. He has published a statement, that several times in the course of the year the wires have been obliged to be taken up, in consequence of the current eating away the insulating medium, and the gutta percha bursting. I allude to Mr. Window, his book can be had at any booksellers. It is this:—”The obstruction arises from the resistance offered by the conducting wire to the passage of the electrical current, and by the creation of an induced charge on the outside of the insulating medium; to overcome which, it is necessary to use powerful currents of electricity, which speedily bursts the gutta percha coating, and destroy all insulation.” He has made this statement, and surely I am not wrong when I join with a gentleman who has tested it, who has tried it, and found it wanting. I am only carrying out that which I have heard, and that which I believe, and I rely on what he has said. In Lancashire, also, a gentleman most positively says, not only once but several times in the year he has been obliged to take the wire up. I never had any practical experience as to the elongation of India rubber, but I know it will contract as readily as it will elongate; its elasticity is one of its chief features, because it will adapt itself to any circumstances, giving way to any practical tension, elongating without doing any injury to its insulating medium, Wherever it has been used it has been found far better than gutta percha.
Mr. Glaisher:–I am very glad to have witnessed the experiments today, because at the observatory at Greenwich, it is most essential to have the best insulating medium possible, in order to secure the perfect transmission of time signals throughout the kingdom. To effect this desirable object, I consider India rubber as a coating will be much better than gutta percha. At present I know of no submarine cable that will last more than five years. I hail this step as a most important one, inasmuch as the new process stands tests where gutta percha totally fails,
Mr. Haines.—I wish to know whether any decisive experiments have been made as to the insulating power of India rubber and gutta percha. There are two different sources of insulation, and I should like to know on which standard the experiments made by Mr. Varley have been conducted.
Mr. C.F. Varley:—I have made experiments with India rubber since we were last here. The question of insulating power is one that requires great delicacy, and the test I used was, how long would a certain piece of wire covered with India rubber retain a charge of electricity until it lost one-half its tension: that is, supposing there are two parts of electricity to charge a wire, how long would it be losing one part? I took some gutta percha, a part of the transatlantic cable, a piece of the Dutch cable, and also some other pieces, and found that the India rubber retained the charge more than ten times as long as the gutta percha. I had a very short piece—only two or three feet—and I could not say how much was due to leakage over the surface; but in order to meet the difficulty I varnished It with shell-lac; and, therefore, I consider, by that test, and with these precautions, India rubber wire retains a charge ten times as long as gutta percha. In the next experiment I took a piece of pure India rubber, dissolving it in chloroform, so as to get it pure, and I really cannot say which material is the best insulator of the two, but I rather think the India rubber in its pure state. Before I sit down I would make one observation with respect to the distention of wire; I have seen several instances, but I never attributed it to the elasticity of gutta percha or India rubber. I think in the case of the Atlantic cable, it is not unlikely it stretched during the course of being paid-out, and when it remained in a state of rest at the bottom of the ocean the iron wire contracted, and perhaps it untwisted a little—that is a difficulty which will occur with any insulated material, either gutta percha or India rubber.
Mr. Wollaston:—There was no outer covering at all at first in the Dover and Calais; it was merely an insulated medium first, about ½ inch of gutta percha only.
Mr. Latimer Clarke:—Mr. West has alluded to a piece of submarine cable laid down to Hurst Castle; it is not exactly submarine as it is buried in the mud, but still remains in use to this day; it gave us considerable trouble, but where dug up shows signs of beginning to decay; whether this is owing to the chemicals, the solvents used in over-lapping the India rubber I cannot say. There are other instances in railway tunnels where India rubber has been used; in 1849 and 1850, India rubber was applied at the Primrose Hill tunnel, and I have seen some which has been down ten years, and when it was taken up, it was as good as new. I have tried gutta percha embedded in asphalte, I have found that preserve it, and do not doubt it would have the same effect on India rubber. There is one point with respect to India rubber which has not been alluded to by Mr. West; and that is, the gum used is of a totally different character to what we were accustomed to at schools and for rubbing out. That was the India rubber bottle; the Para, which is now used, is not the East Indian gum, and does not undergo any change, therefore it may be serviceable. With respect to the insulating property, I have seen two miles of the wire, and it seems to me quite equal, if not better, than the gutta percha now in use; therefore I have no doubt it will prove a very valuable adjunct for telegraphic purposes, and I, for one, would not hesitate to use it.
Mr. West:—With reference to what has fallen from Mr. Latimer Clarke, I perfectly coincide with all he has uttered. The East Indian gum is plastic
on variation of the temperature, and becomes almost a glutinous mass; whereas the Para gum will stand a very high temperature without any injury at all; therefore, I think the observations of Mr. Clarke tend to confirm all I have previously said. I candidly confess there was a difficulty of manipulation—a difficulty to make a solid mass; but if you will only subject this wire to any rational test it is likely to undergo in its use in the world, I think you will have reason to find it, at all events, if not the best, a very perfect thing. (Hear.)
Mr. Walcott:—What is the relative cost of the two?
Mr. West.—I am not prepared to give an answer, but I should think the cost would be in favour of India rubber, because a smaller diameter of India rubber will have a greater effect and will be a better insulator, than a larger diameter of a material like gutta percha. Speaking comparatively, I should say the cost price of one would not exceed the other.
Mr. Walters:—Have you got anything to say with respect to the covering of the cable?
Mr. West (exhibiting it):—There is India rubber-wire surrounded with hempen plaiting; it is fibrous, and saturated with a material that will have the effect of preserving the wire for any period of time, either under the water or in air, without any effect upon the wire itself inside. The material with which it is saturated renders it almost an insulating medium, but not quite. Being fibrous, of course there is a certain porosity, but it prevents the air having an injurious effect on the India rubber. It is on the principle of the sash-line, only the hemp is saturated with a solution which will preserve it in the manner I have described. This can be adapted to water-courses where there are not rapid streams, and there will he quite sufficient specific gravity to sink it to the bottom of the ocean. Of course this is not intended for in-shore purposes; there it would be necessary to use a heavier cable to ensure ponderosity as well as security.
The Chairman:—I have been very much enlightened by what I have seen, and by the information I have derived. I thought at one time we were going to have an unpleasant discussion as to relative merits of India rubber and gutta percha. I know both substances are elastic and squeezable, and as all parties are squeezable at the present time, I hope they will combine for the common good of communicating by telegraphic means, and I, for one, shall always be glad to listen to any new light that may be thrown upon the subject.
Mr. W. Silver:—I cannot allow this opportunity to pass, incapable as I am, without thanking the gentlemen present for responding to our invitation, and witnessing the tests that have been presented to you to-day. The discussion has been an interesting one, and I feel personally indebted to Mr. Wollaston for the course he has taken, and the opinions he has given us the credit of entertaining. I see here so many gentlemen of the highest scientific knowledge, that I am reluctant to come before you, even to make these few observations; but there is one circumstance connected with the undertaking, which, I am sure, will gratify you all, and that is, if success attend our efforts, we intend to employ female labour as much as possible. With reference to the difficulties we have laboured under, I wish to say, we are not prosecuting this work relying on our own strength, we look for help from above.
Should it not be convenient to gentlemen present to inspect the works to-day, on application an order to view them will be forwarded immediately, and with the greatest pleasure, to all who may desire it.
Votes of thanks were then passed to Messrs. Silver, Mr. West, and the Chairman, and the company separated.
The text below is taken from a copy in the library of the Institution of Civil Engineers of an 8-page pamphlet on the same subject, published in 1860. The report of the May 1859 meeting in this edition, which is a condensed version of the text above, is omitted.
Following the introductory notes, this edition includes a story from a trade publication about an earlier meeting held on March 12th 1859. Another contemporary newspaper account gives this information about the March meeting:
On Saturday last, at two o’clock, a meeting of gentlemen interested in the progress of telegraphic communication was held at the works of Messrs Silver and Co., Silvertown, North Woolwich, for the purpose of hearing explanations with respect to the “Patent Caoutchouc Insulator” of that firm.
The company left the Fenchurch-street station, where carriages had been specially retained for their use, at one o’clock, reaching Silvertown about half-past one. Lunch having been disposed of, Mr C. West, at the request of Messrs Silver, came forward to give some explanations in connection with the subject.
The pamphlet’s deprecatory comments on the use of gutta percha insulation were belied by the almost universal success of that material for submarine cables for the next eighty years.
Caoutchouc (India Rubber) is impermeable by water, in all conditions and under all circumstances. The highest degree of pressure yet applied has failed to force a single particle of fluid through the thinnest sheet of this material. It is unaffected by extreme degrees of heat and cold, and its flexibility, durability, and elasticity have long been familiar to every one. In the form of ebonite it repels water and radiates heat.
A good and durable insulator is absolutely essential for securing an efficient, lasting, and consequently economical submarine or subterranean line of telegraph. The material necessary to effect a perfect insulation of a telegraphic wire must be tough, or it will give way under pressure; it must be dense, so as to prevent either the escape of electricity or the infiltration of water; it must be pliant and elastic, to accommodate itself to the coiling and uncoiling of the cable; and, lastly, it must be unaffected by the temperature, moisture, and dryness of the atmosphere, to resist the conditions to which it may be exposed, either before or after it is laid down.
That all these desiderata are found in the India Rubber (Caoutchouc), is testified by the condensed accounts of the experiments made at Silver Town. These, and the letters printed in the Appendix, show that it combines all the qualities proved by experience to be necessary for perfect insulation. Flexible, impermeable, homogeneous, and the finest non-conductor of electricity, its thinnest film secures the perfect insulation of under-water and underground wires. Ebonite supplies an effectual, enduring, and almost indestructible means for insulating the ordinary air-lines. The highest scientific authorities have extolled its high insulating power and low inductive capacity. In addition to tho testimonials printed elsewhere, it may be said that a land-line laid fifteen years since by Jacobi, at St. Petersburg, was found perfectly sound when taken up.
An almost uninterrupted series of failures is an incontestible proof which must have convinced every unprejudiced mind that the substance hitherto used as an insulator must be abandoned. Prepared with the greatest care, and regardless of expense, it is full of imperceptible flaws; exposed to the pressure of the ocean, these flaws rapidly increase, and soon become fatal to the efficiency of the cable. For underground telegraphs it is totally unfit, from its liability to rot. For submarine purposes, cables so insulated, even the very best of them, only succeed, under the best of management, in very temperate climates and on short lines, where they can be taken up and repaired. From the proneness of this material to melt at even a comparatively low temperature, the safe transport on shipboard of cables so insulated is practically impossible. Its employment for deep-sea lines is, therefore, a waste of time, money, and opportunity. Those best acquainted with the history of electric telegraphy during the last few years, well know the truth of this. Faint indeed would be the hopes of accomplishing a complete system of telegraphic communication, if no better insulator could be procured than that whose numerous failures are on record.
The Submarine Telegraph, after all the phases of theory through which it has passed, with but equivocal credit to inventors, seems at last destined to feel the perfecting hand. The importance of procuring a perfect insulating medium is one of the greatest philosophical desiderata of the day. Various have been the speculations advanced as to the merits of this, that, and the other material adapted to the covering of submerged wire. One day saw gutta percha in the ascendant, the next brought caoutchouc to the head of the list; and, again, the cable construction as the best appliance was put forward. The contest was upon the principles of universal utility, the race for precedence in one of the greatest discoveries of modern times, and the victory in a commercial as well as scientific point of view well worth the aspirations of genius, and the unceasing competition of art. It would, however, appear that among the host of competitors the most successful solution of the problem has been reserved for Messrs. Silver and Co., of Silver Town, on the North Woolwich line, at whose India rubber works, on Saturday last (March 12 ), several gentlemen eminent in the commercial and scientific world attended by invitation to test the system adopted by the company. There were more than 200 gentlemen assembled, among whom we recognized—Dr Tyndall, F.R.S.; Col. McLean, R.A.; Capt. Mitchell, Rev. H. Brown, Rev. H. Douglas, Messrs. C. Vignolel, W. Whitehouse, S. Morley, Walker, Glass, Macgregor, Meadows, White, J. Rees, G.W. Saltwell, J.S. Brooking, Westgarth, Varley, Courtney, Andrews, Atkins, Armstrong, Saward, &c.
The proceedings were opened by a gentleman immediately attached to the facture of the telegraphic wire under the system, the patent for which is the property of the Messrs. Silver. He stated pertinently the object for which the gentlemen present had been invited to meet, and directed the earnest attention of his audience to the experiments about to take place in proof of the great superiority of the insulating material which had been manufactured in the establishment. Gutta percha, it was observed, had been found wanting in those essentials necessary for all the requirements of a submerged wire; and, although it led to a depression of the hopes so cherished by all, the failure of the great trial of the Atlantic cable has not rendered the intelligent portion of the community sceptical of eventual success in marine telegraphic communication. China, India, Australia, and America are still to be brought within speaking distance, and where facility and rapidity of intercourse are so necessary to civilization and progress, it is not possible that the submarine telegraph could be permitted to remain unmatured. The Messrs. Silver have truly taken a step in the right direction. They have produced an insulating medium which will supply all the requirements in which gutta percha has so signally failed. The great difficulty of applying India rubber from the beginning was that it could not be rendered sufficiently plastic to be drawn over the wire as a tubing, but had to be wound spirally around it, and then solidified by solvents. This union, especially in long lengths of cable, became defective, and the permeation of the water became the vitiating consequences. It now happens that the fact of gutta percha being so easily affected by heat, a quality at first highly prized, occurs to the defeat of all the projects of submarine telegraphs in which it has been used. In the tropics it has been found perfectly useless, and in the recent Atlantic cable some experiments were made upon the wire with which it was constructed, when it was found that a high temperature greatly impairs the excellence of the insulation. A coil of the completed cable, which gave only 3 degrees of deflexion in the needle of the galvanometer as the measure of imperfection when the thermometer stood at 42 degrees, gave 64 degrees of deflexion as the measure of imperfection when the temperature of the air rose to 59 degrees Fahrenheit. This, together with other causes, has rendered it unsuitable for the purposes required; and many hundreds of miles, both at home and abroad, have had to be taken up, after they have been buried only a few months, at enormous cost, having been found utterly unserviceable.
Such being the case, it suggested itself to men of science, that could India rubber be made sufficiently plastic to act as a homogeneous covering, it would supply the faults of continuity and insulative power, so evident in gutta percha under certain degrees of heat. This problem has been solved by the Messrs. Silver; and it was to witness their system severely tested, that the meeting took place at their India rubber works.
The meeting was addressed by Dr. Tyndall, Mr. Whitehouse, and other gentlemen. The experiments were most successful. The wire, as covered, after being wound on, was first exhibited, when it was shown that in that state the India rubber was not united, and that the water could permeate through the interstices. It was then shown in its complete state, when its hitherto faulty character had totally changed, and it had become a perfectly solid tube, impregnable to water even under hydraulic pressure of upwards of a thousand atmospheres. Portions of the wire were handed round for the inspection of the visitors, and, upon being cut open, the India rubber wound round them had become perfectly solid and homogeneous. Experiments in further proof of its insulation were then made upon coils of wire of a mile each, which were placed in water. Other experiments followed, among which was one upon a length of fifty yards, which had been cut after completion into half-yards, and then joined again; consequently there were 100 joins. To all acquainted with telegraphic matters, the importance and value of this experiment are evident. The insulation was perfectly retained after having been placed for a considerable period in a strong solution of salt and water. It was afterwards put in boiling water, and even under that ordeal the insulation still continued perfect.
The experiments being ended, Mr. Samuel Morley expressed, on the part of the meeting, the great satisfaction with which the experimental proceedings had been regarded by all; and felt assured that in wishing every success to the Messrs. Silver in their invaluable undertaking, he spoke the sentiments of all present.
—Mining Journal, March 19, 1859.
Report of the meeting of May 27th, 1859 omitted here– see above.
Fernside Villa, Red Hill, Reigate,
March 14, 1859.
Enclosed you will find a couple of specimens of copper wire covered with India Rubber, and a copy of the label that was attached to the larger size specimen.
Two specimens have been lying during the whole period in a drawer in my office.
The larger specimen is interesting in an electrical point of view, inasmuch as it shows that India Rubber, during a period of 101 years, under very unfavourable circumstances, presents no symptoms of perishing
I have enclosed you a specimen of Gutta Percha stripped from the wire that has been underground for a period of five years. The disease in this instance spreads from within, outwards.
CHARLES V. WALKER.
The Electric and International Telegraph Company,
Lothbury, September 13th, 1859.
I have tested the piece of India Rubber you last sent me, containing 100 joints. The result is very favourable for India Rubber. Compared with Atlantic Strand and three coats of Gutta Percha, it tests from 50 to 70 times better as an insulator.
I tested it very severely for a long time, and it resisted the test perfectly.
CROMWELL F. VARLEY.
Rodney Hall, Jamaica, October 19th, 1859.
I sent the length of cable to my friend Dr. Smith of the railway, and inclosed you will see what he says; if there had been any appearance of defect in the thing, you would assuredly have beard of it. The little piece I have got is as perfect as it could have been when it left Silver Town.
Calcutta, March 10th, 1860.
When the wire you sent me arrived, it was opened. The whole was carefully examined in my presence, and with a satisfactory result. The covering seemed perfect.
Jamaica, March 20th, 1860.
This is to certify that the accompanying piece of telegraphic cable, sent out by S.W. Silver and Co., has been in my possession from about the 1st of November, and it appears to have undergone no change whatever, save where a too curious person cut it round to inspect the wires. I do cot believe it was exposed to the sun; but, although otherwise directed, it must have been often or mostly in open air.
Lower Mall, Hammersmith,
April 18th, 1860.
India Rubber, as a covering for telegraphic wires, is very superior in insulating power to Gutta Percha. The discharge current, so obstructive in the transmission of telegraphic messages, is also much less in the former than in the latter. I speak only of results obtained under the ordinary pressure of the atmosphere, and at the usual temperature, my experience not extending further.
South Eastern Railway Electric Telegraph, Tunbridge,
May 10th, 1860.
In reply to your inquiry: I placed two of your India Rubber Covered Wires in the Martello Tunnel at Folkestone (the length of which is 28 chains) on May 12th, 1859.
I tested them on May 7th, 1860, with six newly-charged cells of the sand battery, and obtained 0 of deflection for leakage on a galvanometer. it gives about 68° with a single cell of the same battery in short circuit.
CHARLES V. WALKER,
Engineer and Superintendent of Telegraphs.
Extracts from a Report dated December 15, 1859, addressed to the Electric and International Telegraph Company by Mr. W.H. Preece:—
“Accompanying this Report is a specimen of the Cable laid between Keyhaven, on the Hampshire Coast, and Hurst Castle,....A similar Cable lies submerged across the Yarmouth River. There are 2 3/8 miles of Cable altogether. This Cable was constructed by Mr. C. West, for the Irish Submarine Telegraph Company, in the early part of 1852. It remained coiled up in a yard during the whole of that summer and autumn, exposed to every vicissitude of the weather, and was eventually submerged in its present position in the early part of 1853, where it has remained undisturbed to the present day. The specimen enclosed was cut in a small creek running into the mud, where it has always been surrounded with water. The Cable, in the greater part of its course, is buried in thick mud, which is covered by the sea from half flood to half ebb. The mud is always moist, and is but little changed by the flow of water over it. The Cable may therefore be practically considered to have always been encased in an equally moist situation.....I have several pieces of this Cable laid down across the railway at different points of the South Western line, which have been down now about three years. I have also two lengths of 150 yards each carried through Tapenage Tunnel, on the South Western line, between Botley and Fareham, fastened to the side of the Tunnel by iron slips, fixed into wooden arms, driven into the brickwork 5 feet from the ground.....This was done in 1856. All these wires remain perfect. The India Rubber shows no sign of decay.
“It will be gathered from the above that I have considerable experience in the use of India Rubber as an insulating coating upon wires. From this experience I have arrived at the conclusion that, as an insulating medium for Submarine Cables, India Rubber, when free from impure ingredients, is as perfect and valuable an article as Gutta Percha. When exposed to the air, both suffer decay. The India Rubber becomes soft and glutinous—the Gutta Percha brittle and unelastic. When protected with well-tarred hemp, and submerged in the sea, both are durable; and, from the experience we have had, show little or no signs of decay as a non-conductor. India Rubber of itself is superior to Gutta Percha; but Gutta Percha, with the assistance of the process now applied to it by the Gutta Percha Company, can be rendered as perfect as practice demands.
“The durability and electrical qualifications of each being equal, it is their comparative economy which will decide the question of their introduction into the construction of cables for cold climates; but in warm climates, owing to the India Rubber being able to bear without deterioration a much higher temperature than Gutta Percha, there can be no question that the former is the more advisable material to employ; and, therefore, for any cable which is likely to be exposed to a greater temperature than 80° either in its transmission or its submersion, I am decidedly of opinion that India Rubber is the proper insulating medium to employ.”
Further Report, dated Southampton, September 10, 1860:—
“Since writing the above, some experiments at the Gloster Road (by Government), and the failure of the Red Sea Cable, have considerably modified my opinion of the comparative value of Gutta Percha and India Rubber.
“There is no question now of the superiority of the latter, and little doubt but that the next deep-sea cable will be constructed with India Rubber as its insulating medium. Its durability when pure is unquestionable. Its high insulating power and low specific inductive capacity are extraordinary; and there can be no question but that it is the Insulating Medium par excellence for Ocean Submarine Telegraphy.”
Extract from a letter dated October 28, 1860, by Mr. W.H. Sowerby, Royal Botanical Gardens:—
“We have not had our telegraph in work the last month, our district office not being open during the winter; but I have this morning tested the line, and find the insulation as perfect as when first the wire was laid down, although the season has tried it well.”
The following extracts from a series of published Reports addressed by Mr. Edward Highton to the Directors of the British Telegraph Company, throw a strong light on the liability of Gutta Percha to fail, when applied to the insulation of underground wires:—
“Having understood that the wires south of Berkhampstead had failed in many parts, I went there yesterday to ascertain the cause of such failure.....I had the earth removed from the wires in various places.....I found wires perfectly good and completely rotten within seven yards of each other.....On opening the first part where the wires were decayed, I observed a whitish-looking plant resembling the spawn of some fungus pervading the soil, and filling every crevice.....Wherever the plant touched the Gutta-Percha wires, the Gutta Percha was rotten.....The breakage that has taken place, and is taking place, in spots over a length not exceeding one-third of a mile, is enough to stop all telegraphing between Manchester and London.” (Report, dated September 5, 1856.)
“At Winslow I ascertained that there was only forty-six yards of iron piping, the wires passing through the rest of the two in wooden troughs. I found the old wires decayed through the entire length of the iron piping, with the exception of one inch at either end.....In one wire in Winslow, the Gutta Percha was so decayed and cracked that the internal copper wire was visible.” (Report, dated September 18, 1856.)
“With reference to my experiments on the action of the mycellium of a fungus in Gutta Percha, I have for some months been growing one of the class called agaricus campestris in contact with Gutta Percha. I find as the result that the mycellium of this fungus does rapidly destroy the insulating properties of Gutta Percha; and, in fact, it appears to decompose entirely this vegetable gum.” (Report, dated May 15, 1857.)
“The several specimens sent will show the complete destruction” (within five months) “of Gutta Percha by the mycellium of a fungus; and prove, I trust, the correctness of the opinion I expressed many months ago.” (Report, dated January 28, 1858.)
London: Judd & Glass, Printers, New Bridge-street, Blackfriars.