Cable

“ A twisted cable of telephone wire may, when each circuit is formed by diametrically opposite wires, be placed in the same tube with similar cables employed for telegraph purposes. The central wire of the cable may be used either as a telegraph line or as a telephone line having an earth return. Another method is to use powerful telephone transmitters and insensitive receivers ; that is to say, make the telephone currents so powerful that the telegraphic induced currents will be small in comparison, and use receivers so insensitive as to suit such currents. ”

“ The cable may run on a level—as when it spans some great gorge between two mountain peaks—or it may be strung up to any incline not too great to make precarious the grip of the grooved overhead wheels of the basket. I was not able to learn what this limit is, but I have never seen a cable run at an angle of over forty-five degrees. Wherever a cable does not form a single great span it has to be supported at varying intervals by running over steel towers to prevent its sagging too near the earth.
A teleferica has never more than its two terminal stations. ”

“ There was a strange, unnatural silence in the ship. Men paced the deck with soft and muffled{66} tread, speaking only in whispers, as if a loud or heavy footfall might snap the vital cord. So much had they grown to feel for the enterprise, that the cable seemed to them like a human creature, on whose fate they themselves hung, as if it were to decide their own destiny.
“There are some who will never forget that first night at sea. Perhaps the reaction from the excitement on shore made the impression the deeper. There are moments in life when everything comes back to us. ”

“ After passing through such elaborate tests, all will be glad to see the final product of so much care and skill. As the long line begins to reel off from the great wheels and drums, we may examine it in its completed and more perfect form. It is only necessary to compare it with the cable laid in 1858, to show its immense superiority. A glance at the two as they appear on the preceding page will show that the cable had grown since first it was planted in the ocean, as if it were a living product of the sea. This growth had been in every part, from core to circumference. ”

“ So they spent more money, laid more cables, failed again, toiled and moiled and worked like beavers for years, until at last in 1866 they finished a cable from Ireland to Nova Scotia that worked like a charm. It was, without exception, the greatest piece of work ever done in electricity, and its history is one of the finest of the many tales of engineering enterprise.
To-day there are about a dozen cables between North America and Europe, and three between South America and Europe. There are cables in every sea and ocean in the world, and across every ocean except the Pacific. ”

“ Cable and Apparatus.
Field and his business associates were extremely anxious that the cable be laid with all possible speed, and little time was allowed the engineers and electricians for experimentation. The work of building the cable was begun early in 1857 by two English firms. It consisted of seven copper wires covered with gutta-percha and wound with tarred hemp. Over this were wound heavy iron wires to give protection and added strength. The whole weighed about a ton to the mile, and was both strong and flexible. ”

“ As I sat watching the cable to-night, large phosphorescent globes kept rolling from it and fading in the black water.
‘29th.
‘To-day we returned to the buoy we had left at the end of the six-wire cable, and after much trouble from a series of tangles, got a fair start at noon. You will easily believe a tangle of iron rope inch and a half diameter is not easy to unravel, especially with a ton or so hanging to the ends. It is now eight o’clock and we have about six and a half miles safe: it becomes very exciting, however, for the kinks are coming fast and furious. ”

“ A type of cable known as the “quadruple pair” was introduced. In this type the conductors are lapped with insulating paper twinned together in pairs, and are arranged in “cores” each containing four twisted pairs laid up together around a centre, usually of yarn, forming a “quadruple pair” core. The cores are laid up together to the number required and sheathed with lead. This type of cable was a great improvement on the earlier “twin” cables, and permitted the formation of a superposed “phantom” circuit on two physical circuits. Diagonal pairs in the same core are selected for superposing. ”

“ Mechanically speaking, the structure of the cable has answered every expectation that I had formed of it. Its weight in water is so adjusted to the depth that strain is within a manageable scope; while the effects of the undercurrents upon its surface prove how dangerous it would be to lay a much lighter rope, which would, by the greater time occupied in sinking, expose an increased surface to their power, besides its descent being at an angle such as would not provide for good laying at the bottom. ”

“ Bad news from the cable. Number four has given in some portion of the last ten miles: the fault in number three is still at the bottom of the sea; number two is now the only good wire; and the hold is getting in such a mess, through keeping bad bits out and cutting for splicing and testing, that there will be great risk in paying out. The cable is somewhat strained in its ascent from one mile below us; what it will be when we get to two miles is a problem we may have to determine. ”

“ The first Atlantic cable gave me the happiness and privilege of meeting and working with the late Sir Charles Bright. He was the engineer of this great undertaking—full of vigor, full of enthusiasm. We were shipmates on the Agamemnon on the ever-memorable expedition of 1858, during which we were out of sight of land for thirty-three days. To Sir C. Bright’s vigor, earnestness, and enthusiasm was due the successful laying of the cable. ”

“ The Company being thus in working order, proceeded to make a contract for the manufacture of a cable to be laid across the Atlantic. For many months the proper form and size of the cable had been the subject of constant experiments. The conditions were: to combine the greatest degree of strength with lightness and flexibility. It must be strong, or it would snap in the process of laying. Yet it would not do to have it too large, for it would be unmanageable. Mr. Brett had already lost a cable in the Mediterranean chiefly from its bulk. ”

“ Every day of my experience in watching over the permanence of the 10,000 miles of cable under my care, confirms me in the opinion that too great caution and vigilance cannot be exercised in the making and laying a thread which is to be removed from all human vision forever, and designed to earn dividends by continuing a perfect conductor of electricity. Upward of 30,000 miles of cable have been laid since the report of the committee was printed, eleven years ago, and much experience has been gained of the exigencies incidental to submerging, buoying, grappling, and repairing ”

“ CABLE. A thick, strong rope or chain which serves to keep a ship at anchor; the rope is cable-laid, 10 inches in circumference and upwards (those below this size being hawsers) , commonly of hemp or coir, which latter is still used by the Calcutta pilot-brigs on account of its lightness and elasticity. But cables have recently, and all but exclusively, been superseded by iron chain.—A shot of cable, two cables spliced together.
CABLE, To Coil a. To lay it in fakes and tiers one over the other.—To lay a cable. (See Laying.) —To pay cheap the cable, to hand it out apace ”

“ Those who had leisure for sleep were able to dream about cable-laying and the terrible effects of too great a strain. The first question which such as these ask on awakening is about the cable, and on being informed that it is all right, satisfaction ensues until the appearance of breakfast, when it is presumed this feeling is intensified. For those who do not derive any particular pleasure from the mere asking of questions, the harmonious music made by the paying-out machine during its revolutions supplies the information. ”

“ The strength of the cable was such that it would not break except under a tension of a little over three tons. The machinery was so adjusted that not more than half that strain could possibly come upon the cable, when the brakes would relax their grasp, the wheels revolve easily, and the cable run out into the sea without a jar. The paying-out machine, therefore, we are far from claiming as wholly an American invention. ”

“ I feel that the toast which I have the honour to propose deserves a foremost place in the toasts of the day, and that you will heartily respond to it, namely, Success to the Telegraph Construction and Maintenance Company, for that Company has laid scores of cables since its formation, and has now successfully commenced, and will doubtless triumphantly complete, the laying of the cable which we have met to celebrate to-day—the fourth great enterprise, I may remark, which the Company has undertaken—the cable that is soon to connect India with England. ”

“ The design of the cable was a subject of experiment by Professor Morse and others. It was known that the conductor should be of copper, possessing a high conductivity for the electric current, and that its insulating jacket of gutta-percha should offer a great resistance to the leakage of the current. Moreover, experience had shown that the protecting sheath or armour of the core should be light and flexible as well as strong, in order to resist external violence and allow it to be lifted for repair. ”

“ I then came back to my house, and gave orders (for which I had a warrant) for a great quantity of the strongest cable and bars of [48] iron. The cable was about as thick as packthread, and the bars of the length and size of a knitting needle. I trebled the cable to make it stronger, and for the same reason I twisted three of the iron bars together, bending the extremities into a hook. Having thus fixed fifty hooks to as many cables, I went back to the northeast coast, and putting off my coat, shoes, and stockings, walked into the sea in my leathern jerkin, about half an hour before high water. ”

“ The part of the cable that is below the ground or the sea is naturally protected against lightning strokes, but somewhere the end of the cable must be brought out to the surface of the earth and connected to some apparatus or machine. ”

“ In the old Atlantic cable the copper conducting-wire weighed but ninety-three pounds to the mile, while in the new cable it weighs five hundred and ten pounds to the mile, or more than five times as much. Now the size, or diameter, of a telegraphic conductor is just as important an item, in determining the strength of current which can be maintained upon it with a given amount of battery-force, as the length of the conductor. ”

“ This conductor is then enveloped in three separate coverings of gutta-percha, of the best quality, forming the core of the cable, round which tarred hemp is wrapped, and over this, the outside covering, consisting of eighteen strands of the best quality of iron-wire; each strand composed of seven distinct wires, twisted spirally, in the most approved manner, by machinery specially adapted to the purpose. ”

“ A man don't stand much show when the end of a inch 'n' a quarter cable snaps at him like a whiplash. I seen a feller on Howe Sound cut square in two with a cable-end once. A broken block's the worst, though. That generally gets the riggin' slinger, but a piece of it's liable to hit anybody. You see them big iron pulley blocks the haul-back cable works in? Well, sometimes they have to anchor a snatch block to a stump an' run the main line through it at an angle to get a log out the way you want. ”

“ The signals are retarded (and this was one of the results of the investigation) in such a manner "that the time required to reach a stated fraction of the maximum strength of current at the remote end," when a given potential difference is applied at the other, or home end, is proportional to the product of the capacity and resistance of the cable, each taken per unit of the length, and also proportional to the square of the length of cable. ”

“ That man who can appreciate the feelings of one who has become suddenly bankrupt may understand the mental condition of those on board the Great Eastern when they were thus tossed from the pinnacle of joyous hope to the depths of dark despair. It was not, however, absolute despair. The cable was utterly useless indeed—insensate—but it was not broken. ”

“ Engineering Demonstration.—Still the engineer of this great undertaking had the satisfaction of knowing that he had demonstrated (1) the possibility of laying over 2,000 miles of cable in one continuous length across a by no means calm ocean at depths of two to three miles; and (2) that, by the agency of an electric current, distinct and regular signals could be transmitted and received throughout an insulated conductor, even when at such a depth beneath the sea, across this{153} vast distance. The feasibility of either of these had been scouted at on all sides. ”

“ In a cable, the wires are so close together that their induction is negligible, while their capacity is so great as to limit commercial transmission through a cable having .06 microfarads per mile capacity and 94 ohms loop resistance per mile, to a distance of about 30 miles. ”

“ For heavy street-car traffic and for places where there are very heavy grades the cable system has been sucessfully employed. The cable, an endless wire rope of one to 11⁄2 inches in diameter, is kept in continuous motion in a slotted groove or conduit below the surface and between the rails, and the connection with the car is made by a grip which can be controlled from the car. The power required to keep the cable in motion without load is large—35 to 75 per cent. ”