LECTURE
ON THE
INSULATION OF SUBMARINE CABLES
.
BY CHARLES WEST, ESQ..
CAPTAIN FISHBOURNE, R.N., C.B., IN THE CHAIR.
Mr. West said the subject of Submarine Telegraphy is one not only of national but of world wide importance.
Countries separated from each other by the broad expanse of oceans have long been desirous of availing themselves of the advantages of the rapid inter-communication which Submarine Telegraphy would give them.
These advantages, socially, politically, and commercially, are so well understood, that it would be a work of supererogation in me to allude to them, and yet with every desire on the part of other nations, and of this country particularly, to establish such a system of intercommunication, Submarine Telegraphy in deep seas has hitherto proved a failure.
This ought not to be, but unfortunately it is too true that it is so. There is not any part of the globe in which these failures have not been developed. The line from Europe to America across the Atlantic, with all its monopolies, if not still-born, died within a few days after its alleged birth. The Mediterranean lines have all proved complete failures; that which was to connect Europe with Africa, from Cagliari to Algiers, being among the number. The lines connecting Africa with Asia were never worked in their entirety. Some sections in the Red Sea, now particularly known as “The Red Sea Cable,” were laid down and worked well for a few months, when suddenly their functions ceased, and this said Red Sea Cable is now included in the category of failures, without the slightest hopes of its resuscitation. The communication between Cagliari and Malta, and also that between Malta and Corfu, have long ceased; and even in the southern hemisphere the same fatality appears to attend the attempt to establish submarine telegraphs as in the northern; the cable across Bass’s Straits, to connect Tasmania with the mainland of Australia, being also added to the list of submarine failures; and last, though not least in importance, we find that the cable ordered by the Government for the purpose of establishing a communication between this country and Gibraltar, but subsequently with its destination changed for service between Rangoon and Singapore, has actually proved faulty, if not totally unserviceable, even before it has left the English shores.
Now with the fact of these repeated failures before us, surely it becomes a matter of necessity that a searching investigation should be made as to their cause, as well for future guidance as to restore the confidence of the public in the possibility of successfully establishing a system of Ocean Telegraphy, which, from the disastrous failures I have enumerated, if not entirely lost, has at least been considerably shaken.
I myself have long had but one opinion on the subject, in which at first I almost stood alone, but which, from recent events, is now shared by the majority of those at all acquainted with the matter, and that is, that the very first principle requisite for the successful working of any Electric Telegraph, either land or oceanic—that of insulation, has been entirely overlooked, either from ignorance or interested motives, and the use of an ineffective and imperfect material been pertinaceously persisted in.
To this point, therefore, the Insulation of Cables, I shall now direct your attention, and I trust to be able to satisfy you that no other result could have been expected from the course adopted by those who have had the management of them than the disastrous failures which unfortunately we have had to record.
In addressing a meeting two years ago on this subject, I stated
“that it must be generally known that the first principle requisite for 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 in glass or earthenware insulators placed in poles. These are seen everywhere throughout the country wherever a 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 to the continued use of Gutta Percha in the construction of the Atlantic, the Red Sea, and the Gibraltar, alias the Rangoon Cables, that the failure of all may be attributed. In fact, the singular occurrences with respect to the latter prove the case against them all. I shall advert to this point presently, but in the meantime will begin at the beginning, and show from published facts how injudicious it was to continue its use, in spite of all the evidence against its efficiency.
Dr. Maclagan, who first introduced it here, states, “that in its elementary composition, Gutta Percha is, like Caoutchouc, a Carbide of Hydrogen, and nearly isomeric with that substance, as the following analysis will show:—
| |
|
Gutta Percha. |
|
Caoutchouc. |
| Carbon |
|
86.36 |
|
87.20 |
| Hydrogen |
|
12.15 |
|
12.80 |
| Oxygen |
|
1.49 |
|
— |
| |
|
100.00 |
|
100.00 |
Dr. Muspratt says:—“It is a question, indeed, whether the elementary composition of the two substances is not precisely the same, the small quantity of oxygen detected by Dr. Maclagan in Gutta Percha being probably derived from the air during the process of purification. Its acknowledged porosity, and the difference in its specific gravity under different conditions, are facts which afford a strong presumption in favour of this view.
The great variation in its density under different treatment imply a peculiar porosity in its structure, which was experimentally verified by Payen.
Having placed a drop of its solution in bisulphide of carbon on a slip of glass, and allowed it to evaporate under the action of an air pump, so as to obtain a thin film of the substance in a state of purity, he observed with the microscope numerous small holes or cavities, which were rendered still more visible by a drop of water; the liquor gradually insinuating itself and rendering the film more opaque, while the cavities were observed, by the means of the lens, to be enlarged.
It was these observations which led this eminent chemist to conclude that the common commercial Gutta Percha, retaining, in consequence of its porosity, a great many minute particles of air, owed to this circumstance its appearance; possessing a less density than that of water.”
Professor Page states:—“That Gutta Percha, when rolled into thin sheets, or drawn into ropes, comports itself like a fibrous substance, which is not the case with caoutchouc. A slip cut from a thin sheet of Gutta Percha may be stretched considerably in one direction, that is in a line with the fibre, but an attempt to stretch it across this is followed at once by a rupture. It is not so with a sheet of caoutchouc, which will stretch equally well in all directions.”
Dr. Muspratt further adds:—“That the porosity of Gutta Percha, which allows a slow transudation of liquids through its mass, is the principal drawback to its use when formed into bottles or other vessels for holding chemical fluids.”
From the testimony of these scientific gentlemen, it would appear that Gutta Percha is porous, fibrous, and cannot be used by chemists when formed into bottles, in consequence of the exudation of the fluids through it. Surely, then, greater caution should have been shown in selecting it as the insulating medium of these vast undertakings, involving such important interests and enormous sums of money.
But there is another point affording an important link in the chain of evidence adduced by these gentlemen, in connection with the subsequent researches of Professor Hoffman, and which have a direct bearing upon the case, to which I will beg to call your attention, as I think it tends materially to elucidate the causes of the failure of these Gutta Percha covered cables. The point to which I allude is the great chemical attraction or affinity which Gutta Percha has for oxygen.
Sir William O’Shaughnessy, who had the superintendence of the Telegraphs in the East Indies, states, in a letter to the Times, dated September 6th, 1858, from which the following is an extract, “that in 1853 the East India Company sent out to India in sailing vessels 700 miles of Gutta Percha covered wire, made by the Gutta Percha Company, and packed by them in solid deal cases. On opening the cases in India some weeks after arrival, in the cold season, and without any exposure in the interval, it was found that the copper wire had in many instances been forced through the Gutta Percha, which bore evident marks of softening by heat.
“We further found that a still more serious change had taken place partially, and was still in rapid progress, by which the Gutta Percha became brittle, broke off whenever bent, and lost all its insulating power. This change had occurred within the unopened cases. To save as much as possible the wire, we coated above 200 miles with tarred yarn, and this arrested the change for a time; still, eventually, we had to condemn as useless about 500 miles of the wire.
“The change of the Gutta Percha from the plastic to the brittle state is the effect of oxydation This is proved by an elaborate series of analyses, made at my request by Professor Hoffman, of the Royal College of Chemistry, on samples of Gutta Percha which had been altered in India.
“Gutta Percha in its natural state contains—
| Carbon |
|
88.00 |
| Hydrogen |
|
12.00 |
When altered by prolonged heat or keeping in cases not even once opened) two substances are formed containing—
| |
|
No. 1 |
|
No. 2 |
| Carbon |
|
63.80 |
|
87.20 |
| Hydrogen |
|
9.20 |
|
10.20 |
| Oxygen |
|
27.00 |
|
22.60 |
“These substances are totally useless as insulators. Wire, surrounded by Gutta Percha thus altered, may be considered electrically as so much uncoated metal.
“The facts now published give a warning which should not be neglected. If ignored or lightly valued, the result will be a great loss of capital, and an infinite disappointment to the community. I have done my duty, without bias or prejudice, in making this communication to all the parties concerned, although I am well aware that I might better consult my own comfort by remaining altogether silent. I wish it, however, to be clearly understood, that I consider it quite practicable to send out the Atlantic Cable, in suitable vessels and with special appliances, without much risk from the causes of injury above described. My object is at present to warn those concerned not to send it as in the Agamemnon, or in ignorance Of the facts described, and neglecting the precautions these facts suggest. Further, I see no difficulty in manufacturing a cable in which the tendency to oxydation and spontaneous heating, and the influence of heat from external causes, may both be effectually counteracted.”
From the foregoing analyses made by Professor Hoffman upon this Gutta Percha covered wire, which had been sent to the East Indies and back under the peculiar circumstances described by Sir William O’Shaughnessy, there is no doubt that Dr. Muspratt has taken the correct view of the case. He, as I have stated, is of opinion that the small quantity of oxygen—1.49—discovered in the Gutta Percha in the analyses of Dr. Maclagan, is not a part of its elementary composition, but had been acquired during the process of its manipulation or purification. Now this opinion expressed by Dr. Muspratt as to the chemical attraction or affinity of Gutta Percha for the oxygen of the air, has been fully confirmed by the subsequent researches of Professor Hoffman.
In the first instance the quantity of oxygen discovered by Dr. Maclagan’s analyses is but small, only 1.49, hut after the Gutta Percha had been sent to the East Indies, although packed in strong deal cases, it had become so altered by prolonged heat and keeping, that two substances were formed, in both of which the oxygen had increased more than twenty-fold. In the one substance, according to the analyses of Professor Hoffman, instead of there being only 1.49 of oxygen, there was 27.00 and in the other 22.60. Here is quite sufficient cause to account for the failure of Gutta Percha covered wires, oxydation changing the Gutta Percha from the plastic to the brittle state, in which state it losses all its insulating properties, and as Sir William O’Shaughnessy truly observes, “wire surrounded by Gutta Percha thus altered may be considered electrically as so much uncoated metal.”
Now it must be borne in mind that this 700 miles of wire sent to the East Indies by the East India Company, were only covered with their insulating media, which had no other covering, either metallic or otherwise. It is most essential that this fact should be held in remembrance, and I will show you why, The Gibraltar , alias the Rangoon Cable, has shown all these fatal symptoms described by Sir William O’Shaughnessy, as attending the 700 miles of wire forwarded to him, this self-same softening by heat, and the protrusion of the wires through the Gutta Percha, even before the Cable had left the British shores, and therefore without having been subjected to the tropical heat to which the Indian wires were.
There have been few summers like that of 1860. It seemed as though it had changed its usual habiliments for those of winter, while winter thus deprived of its own clothing borrowed its garments from the frigid zone, and, consequently, by these freaks of nature, we have had an unusually cold summer and an intensely cold winter.
These changes of the seasons, however injurious and unpalatable to us, could not have been more favourable for the manipulation and preservation of Gutta Percha covered wires; and yet, despite the unusual coldness of the weather during the last summer, and its intense severity in the winter, the Gutta Percha of the Gibraltar, alias Rangoon Cable, has exhibited all those fatal symptoms usually attributed to the effect of tropical heat.
The Times, in giving a report of this singular occurrence says:—“It is only two years since an immense sum was hopelessly lost with the Atlantic Cable, which, of course, like all modern ropes, was hurriedly constructed and laid down over an imperfectly known and ill-adapted route; and though, in consequence of the great care bestowed upon its submergence, the task was for the time successfully accomplished, yet, as expected by many, it enjoyed but a very brief period of profitless existence. It is only a few months since au important line of cable of notoriously unsuitable construction, and totally unadapted for its purpose, was laid and lost in the Red Sea, and the country thereby saddled with the payment of 4½ per cent. on a capital of £800,000 for 50 years. Now, again, we have another mishap, another unmistakeable indication of failure and money wastefully expended. The much praised and costly cable for the Rangoon and Singapore line is now found to entertain within itself the elements for its own destruction, such undoubted evidences of ‘heating’ or spontaneous combustion having set in as to render the despatch of the vessels to a warm climate impossible. That these most lamentable and expensive failures have brought all telegraphic enterprises into discredit, and have tended to hinder the spread of the greatest and now most necessary element of modern civilisation, is much to be feared. Yet, on the other hand, there is reason almost to believe that no failure has here occurred which could not and ought not to have been avoided with ordinary care and discretion on the part of those entrusted with the duty of superintending the manufacture. This last disaster, however, is one of the most unaccountable that has yet occurred to any cable. Before its construction was decided on much time and a great deal of public money were expended in a series of experiments as to the best form of cable to he used. The engineering supervision of the work was then entrusted to almost the same gentlemen, under whose auspices the Red Sea Telegraph had been brought to so sudden and so unsatisfactory a termination. It was completed within the last few weeks and shipped on board three powerful 2,000 ton steamers, two of which, the Rangoon and the Malacca, were built expressly for the purpose by Messrs. Palmer and Co. The third ship, the Queen Victoria, of equal size and power, is a chartered vessel. In the beginning of November, when a considerable portion of the line had been coiled away in the holds of the ships, a very marked tendency to an increase of temperature was observed. In the hope that this might prove only a temporary inconvenience, little importance was attached to it. The temperature, however, continued to increase; until shortly after the sailing of the Queen Victoria, a few weeks since, the temperature of the coils was found to have augmented to 80 deg. Fahrenheit, and showed such symptoms of further increase as to render it in the highest degree inexpedient to trust the ships containing it on a voyage of several months’ duration in a tropical climate. As to the cause of the accident, no one appears to have a decided opinion as yet. Professor Miller, and other scientific men, have been consulted on the subject, some of whom seem to think that it is due to the oxydation of the iron wires.”
Now the opinions of these scientific men who have been consulted on the subject, some of whom, it is alleged, seem to think that the heating of the Gutta Percha is due to the oxydation of the iron wires, is in all probability to a certain extent correct, and proves the hypotheses of Dr. Muspratt and others, of the great affinity which Gutta Percha has for oxygen, the supply from the air in this case being augmented by a further supply from the oxide of iron.
It should be held in remembrance, however, that the 700 miles of wire sent to Sir William O’Shaughnessy had no outer covering whatever over the Gutta Percha; consequently, in that case the fault could not have been from the iron wires, seeing that there were none; and as the symptoms of “heating” in the Rangoon Cable are precisely the same as in the Indian wire, it is only reasonable to infer that the causes producing these similar effects are also precisely the same.
However, as my object is to deal with facts rather than with theories, I will pursue this subject no further. This self generating of heat in the Gutta Percha, be the cause what it may, is indisputable. It showed itself in the Atlantic Cable, where, both in the Agamemnon and the Niagara, large quantities of wire were obliged to be cut out, and though the remaining portion was successfully submerged with the metallic conductor unbroken, yet the insulating medium was so diseased that the communication was maintained only for a day or two, and even that in a most unsatisfactory state, and, after a month of lingering inutility, ceased entirely.
In the Red Sea Cable there is no question that the same spontaneous heating of the Gutta Percha took place previous to its being submerged. Some of the portions of the defunct cable, which Were picked up, showed, upon examination, holes in the Gutta Percha large enough to contain a good-sized pea, which had been caused by the action of the electric fluid; and the Superintendent of the line, in his Report says, “the sea water being thus admitted to the copper wires, the action of the electricity and sea water decomposed an inch or two of the copper wires, which started apart, and the connection was thus lost.” The telegraph worked from the 29th May, 1859, to the 10th February following, so that nearly nine months only were required for the electricity to work a passage for itself through the diseased Gutta Percha. And now, in the case of the Gibraltar or Rangoon Cable, this self-generating of heat in the Gutta Percha insulating medium has shown itself in such an unmistakable manner, even before it has left the shores of England, and during one of the most intensely severe winters that have been known for many a year, that it becomes a question whether it will be advisable to incur the expense of laying it down. Should that expense be decided upon, rest assured its career will be a very brief one, and, like its predecessors, its powers of insulation will, from the same causes, speedily cease.
But it will naturally be asked, why was the use of this self-destructive material so injudiciously persisted in? Was there no other substance to be found more adapted to the purpose? To the first question I can give no reply; to the second, however, I am in a position to state most unequivocally that there was a material to be had, far more suitable for the purposes required, possessing ail the essential qualifications necessary for the important object to be attained, and that is—India Rubber. At the meeting I have adverted to I stated:
“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 a 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 an 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 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:—
Chemical Department, H.M. Dockyard, Portsmouth,
Dear Sir,—
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
May 25th 1859.
Mr. West, in continuation, said:—For twenty years I have been the sole and consistent advocate of India Rubber. A very eminent firm in the city, Messrs. Silver and Co., extensive manufacturers of Caoutchouc, with large appliances for carrying out any contracts, had taken this matter up; and by experiments made at Silver Town, before a numerous body of highly scientific individuals, India Rubber was shown to be a perfect insulator, impermeable to water under any temperature, or any pressure. Mr. Varley, the electrician of the Electric Telegraph Company, there stated that he had made experiments with India Rubber; that he had taken some Gutta Percha, a part of the Transatlantic Cable, a piece of the Dutch Cable, and also some other pieces, and he found that the India Rubber retained the charge more than ten times as long as Gutta Percha.
The Gibraltar Cable was at this very time under consideration; and surely with these facts before the engineers and electricians, who had the management of this Cable, common prudence should have dictated to them the absolute necessity of further experiments before they so hastily adopted this questionable Gutta Percha, although coated with a new substance called Chatterton’s Compound, which was to be the panacea of ail its previous ills, and to render it perfection; with what result the heated Cable has shown. Had they done so a large sum of money, now likely to he lost to the country, would have been saved.
Her Majesty’s Government, however, entertaining doubts on the subject, and with greater prudence than was shown by these gentlemen, subsequently ordered a Committee of Inquiry upon Submarine Telegraphic matters, and I am happy to say that the result of that inquiry, although not yet presented to the House of Commons, will show that India Rubber is far superior to Gutta Percha, or any other material submitted to the Committee of Inquiry.
Its durability, which only time could test, I am enabled now to show you. Here is a sample of an India Rubber covered Cable of four wires, which was laid down so far back as the year 1852, between Keyhaven and Hurst Castle, and the following is an extract from a Report of Mr. W.H. Preece, of the Electric and International Telegraph Company, dated December 16, 1859:—
“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.”
Here is also a quantity of the same wire which has been for a long time both in fresh and salt water. It is a four-strand cable, laid up over a rope yarn well saturated with tar. You will perceive that the tar is all gone, and the rope yarn itself so decomposed that it has lost its tenacity, so that it is readily broken by the slightest jerk, while the India Rubber remains as perfect and as sound as when first put on the wire. (Several pieces were broken by way of illustration.)
I am very happy to state that I have the reports of several practical electricians in favour of India Rubber Insulation, among others from Professor Wheatstone.
That eminent electrician states, that “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.”
That gentleman has exemplified, by example as well as precept, his confidence in the excellence of India Rubber, for he is actually using it in carrying out his system of domestic telegraphy; and the rope which you, now see in some parts of London suspended over the house tops contains fifty wires, all separately insulated with India Rubber.
It is evident from what has been stated by Sir W. O’Shaughnessy, respecting the Indian wire, and from other instances, that temperature has a considerably destructive effect on Gutta Percha. This is not so with India Rubber. I have placed it in boiling water and immediately transferred it to an ice pail, and again returned it to the boiling and subsequently to the ice without the slightest injury to it; and I am enabled to state that you may send it to the East Indies without the least fear of its sustaining injury from either heat or cold, You may even, if you think necessary, either send it in ice or boiling water.
Another project to connect England and America across the Atlantic is now in contemplation, hut here the line is to be laid in sections from Scotland, the Faroes, Iceland, Greenland, and the Labrador Coast. This will have, at all events, the advantage of short distances; and if the errors of omission and mission of the past be avoided in the future—if, instead of constructing it in secret, trusting to the overwearing confidence of self-sufficiency, and launching it when complete under such superintendence with all its imperfections on its head—if, instead of doing this, the persons interested will invite the cooperation of the scientific world, will call to their assistance men acquainted with the indispensable requirements for its construction, and seek the aid and advice of those possessing a practical knowledge of the element to which it is destined, and of the mode of placing it there—if they will do this, and collect, collate, and cull from such sources all that may be deemed valuable, and reject all that is problematical—if they will search in a spirit of humility, and not of self-confidence, and place their reliance on an all-wise Providence for their guidance—if this is done, I have no hesitation in predicting that the next attempt to establish a Cable across the Atlantic will be as successful as the recent ones have been disastrous.
Captain Fishbourne. —I would wish to observe that it is not our practice at this Institute to ask questions at the conclusion of a lecture, but should any gentleman desire it, Mr. West will be very glad to answer any question that may be put to him.
The Rev. Mr. SMITH Warleigh.—This is a most interesting subject, and one to which I have particularly turned my attention. I should like to ask, if you can tell me the difference of cost between India Rubber and Gutta Percha, applied as an insulator.
Mr. West.—If you mean merely as to weight, India Rubber will he more costly; but if you speak as to comparative efficiency, India Rubber will cost less.
Captain Fishbourne.—That is another question. I apprehend Mr. Warleigh’s question is as to the actual cost.
Mr. West.—I don’t know the exact cost of Gutta Percha, but I know very well that I could manufacture a cable with three wires, of this description (exhibiting wires) and the insulation perfect, by which I should have three different conductors, each separately insulated, instead of only one conducting medium, and could do it at a less cost than was paid for the single wire constructed for the Gibraltar Cable.
Captain Sir Frederick Nicolson, Bart., R.N.—The other night, at the Society of Civil Engineers, I asked the question as to the cost, and the answer was that the difference between Gutta Percha and India Rubber was 50 per cent.
Mr. West.—I think I have already replied to that question. I will undertake at any time to make an India Rubber cable with three separate wires perfectly insulated, at less cost than was paid for the single wire of the Gibraltar Cable.
The Rev. Mr. Warleigh.—Is it owing to the small quantity of India Rubber required for the insulation that, practically, it becomes less in price than Gutta Percha?
Mr. West.—That is so.
The Rev. Mr. Warleigh.—I have both heard and read a good deal on this subject. it is one in which I am very much interested; not personally, but as an Englishman. Another question I put at the Society of Civil Engineers which never has been answered. India Rubber is very elastic, and for that reason is there not more difficulty in paying it out, from there being a greater probability of the wire snapping, though the insulating medium be as perfect as before?
Mr. West.—That is one reason why I recommend, at all times, instead of one conducting medium to have three strands insulated similar to the one lying before me, because there is a greater degree of elasticity with three strands than a single wire. Upon that principle I always recommend that there should be more than one conducting medium.
The Rev. Mr. Warleigh.—You said just now that each wire was insulated separate from the other.
Captain Fishbourne.—The real answer to your question is not that the wire will snap; it will rather be protected by the elasticity of the India Rubber. The mechanical strain is met by the outer coating, which prevents any difficulty in laying it down. Mr. West’s paper did not go to the question as to the outer covering. The question of tension is apart from insulation. The question put to Mr. West involves the mechanical construction, which should bear the weight in paying it out; that, he says, may be provided for by there being three strands instead of one single insulation,
The Rev. Mr. Warleigh.—When I was asked to come here I was not aware of the principle that was intended to be advocated; and I am very much pleased to hear that my opinion falls in with that of Mr. West. The chairman has answered the question I put most satisfactory. I do not think from the explanation that there is any difficulty in paying such a cable out. It seems to me just the very thing that we, as lovers of our country, desirous of successfully carrying out this national object, would require as a means of insulation.
Captain Fishbourne.—We are very much obliged to Mr. West for raising this question, and for the very able and interesting manner in which he has explained it. Nothing has been introduced in the course of the lecture that is at all unnecessary or irrelevant to the subject. It is a most important question. I have not myself entered into the subject of the various means of insulation, but the failure of the Atlantic Cable has shown us there was a want; and I felt confident that in time Providence would enable us to get out of the difficulty and satisfy it. I always felt that we should have the means of communicating with our transatlantic brethren, and that we should be able, as Mr. West says, to communicate our sentiments to them in as rapid a manner as the necessity of the case might require. In reading the interesting paper to us this day it should be taken in connection with the lecture of Captain Nolloth.
The Rev. Mr. Warleigh.—Will that also be published?
Captain Fishbourne.—It has already been published with the other transactions of the Society.* The difficulty in paying out a cable is, that you may get a greater strain and be obliged to apply powerful breaks in order to prevent its running too fast. On the other hand, when you come to an unequal bottom, by its own gravitating force it may be destroyed. No doubt, no cable, however well constructed for bearing the mechanical strain, can be of any utility unless its insulation is perfect. On behalf of the Institution, we tender our thanks to Mr. West for this very interesting lecture.
