Anchor cable

“ A cable is carried out from the mainland at Crookhaven for 7 m., and the outer end earthed by connexion with a copper mushroom anchor. Another earthed cable starts from a similar anchor about 100 ft. away near the shore line of the Fastnet rock, crosses the rock, and is again earthed in the sea at the distant end. If a battery on the mainland is connected through a key with the shore end of the main cable, and a speaking galvanometer is in circuit with the short cable crossing the Fastnet rock, then closing or opening the battery connexion will create a deflection of the galvanometer. ”

“ Winding these fine wires into a cable made a flexible rope that was essentially a three-phase material—with the vacuum of space acting as the third phase. With a tensile strength above a hundred million pounds per square inch, a half inch cable could easily apply more pressure to that anchor than it could take. There was a need for that strong cable: a snapping cable that is suddenly released from a tension of many millions of pounds can be dangerous in the extreme, forming a writhing whip that can lash through a spacesuit as though it did not exist. ”

“ In “weighing” anchor, that is in pulling it up from the bottom to bring it on board again, the cable is slowly wound up by the capstan, and as the cable is shortened the ship is drawn along to a point nearly over where the anchor rests, when—the pull at the cable continuing—the shank is raised into an upright position, and the fluke and arm, instead of dragging up a great piece of earth, remove but a small portion, as may be seen by the dotted lines in figs. 4 and 5, which show the earth to be removed before the anchor can be drawn from its hold. ”

“ The essential feature of the patent is a nonyielding support or anchor at one end of the cable, and a yielding, tilting, or rocking support at the opposite end, consisting of outwardly inclined shears or some equivalent structure held movably at the base, and a counterweight on the outer side. It is to be observed that rigidity of the head tower is a sine qua non, necessary to produce tension of the cable ”

“ Because it is generally necessary to work lively after most of the sails are set. After the sails are shaken out on board of a ship, they don't want to wait a long time to heave up the whole of the cable. Archie and Syl shall have their stations at the cable, and Con and Hop at the jib-halyards. Now, just to show how it is done, you may heave up the anchor to a short stay; that is, haul in on the cable till the bow of the boat is nearly over the anchor ”

“ The single-wire sheathing is applied to cables to be laid in shallower depths, such as coast-waters; and the heavy-strand sheathing is for protecting the cable in anchorages and on sea-beaches. The light-sheathed cable is called 'main' or 'deep-sea cable;' the medium is called 'intermediate;' and the heavy-sheathed cable is called 'shore-end.' There is seldom more of the last than ten or twelve miles, to carry the cable well out of reach of the abrasion of storm-shifted boulders and coast anchorage. ”

“ The science of making, testing, and laying cables has so much improved that an undetected fault in an insulated wire has now become literally impossible, while so much are the instruments for signalling improved, that not only can a slight fault be disregarded if necessary, but it is even easy to work through a submarine wire with a foot of its copper conductor stripped and bare to the water. This latter result, astonishing as it may appear, has actually been achieved for some days past with the whole Atlantic cable on board the Great Eastern. ”

“ It consists of an exchange of currents sent alternately every ten minutes by each ship. These not only serve to give an accurate test of the continuity and insulation of the conducting-wire from end to end, but also to give certain signals which it is desirable to send for information purposes. For instance, every ten miles{121} of cable paid out is signalized from ship to ship, as also the approach to land or momentary stoppage for splicing, shifting to a fresh coil, etc. The current in its passage is made to pass through an electromagnetometer, [34] an instrument invented by Mr. Whitehouse. ”

“ In the case of the ungrounded sheath, the latter charges at once through all its length to the voltage of the high-potential wire; at some point, a wire within the cable is close enough to the sheath for an arc to strike across, and the trouble begins. All the wires in the cable are endangered if the cross be with a wire of the primary circuit of a high-tension transmission line. Any series arc-light circuit is a high-potential menace. Even a 450-volt trolley wire or feeder can burn a lead-covered cable entirely in two in a few seconds. ”

“ Altogether, in the four cables there would be 23,132 miles of wire, or enough to go nine tenths of the way around the earth.
The wire in a strand, he said, was looped around “shoes” at each end of the bridge, and ran in a continuous length, like a skein of silk. When the strand was completed, the ends were spliced together. When the strand was started, the wire was temporarily fastened at one end and passed around the shoe. Then it was slipped over the carrier, a signal was given, the cable started, and the carrier proceeded merrily on its way across the river. ”

“ The attempt to insulate more than one conducting-wire or medium would not only have increased the chances of failure of all of them, but would have necessitated the adoption of a proportionably heavier and more cumbrous cable. The tensile power of the outer or wire covering of the cable, being very much less than that of the conductor within it, the latter is protected from any such strain as can possibly rupture it or endanger its insulation without an entire fracture of the cable. ”

“ Arrived at the place from which the cable is to be laid, the first thing done is the laying of the shore-end from the ship at her anchorage to the cable-hut on the beach. The cable-hut is generally a small erection of galvanised iron or stone and lime to contain the end of the cable and a few instruments. Cables are never if possible landed in harbours, or where there is danger from anchors. A suitable retired cove is generally selected, not far distant from the town where the telegraph office is, and a short land-line connects the end of the cable to the office. ”

“ The weight per nautical mile of dielectric is the same in both cables, but each copper conductor of the former weighs 300 lb. per mile as compared with 160 lb. per mile in the latter. The transmission efficiency of the cables is practically equal, but the continuously loaded cable provides an additional circuit by superposing. Experiments conducted on this cable in 1914 proved the possibility of obtaining four circuits from a continuously loaded 4-wire submarine cable by introducing an improved method of balancing the electrostatic capacity of the conductors. ”

“ Induction is always proportioned to the conductivity of the mass in which it appears; as steel is an excellent conductor, the armour of an ocean cable, close as it is to the copper core, has induced in it a current much stronger, and therefore more retarding, than if the steel wire were absent.
A word now as to the second difficulty in working beneath the sea—that due to the absorbing power of the line itself. An Atlantic cable, like any other extended conductor, is virtually a long, cylindrical Leyden jar, the copper wire forming the inner coat, and its surroundings the outer coat. ”

“ This combination for the length involved was based on Professor Thomson’s law for the working speed of a cable, as depending inversely on the resistance of the conductor as well as on the electrostatic capacity of the core. The armor consisted of a combination of iron and hemp, each wire being enveloped in manila yarns. The object of incasing the separate wires in hemp was (1) to protect them from rust due to exposure to air and water, and (2) to reduce the specific gravity of the cable, with a view to rendering it more capable of supporting its own weight in{181} water. ”

“ 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. ”

“ He described 'high tension cables for 3,000 volts' having paper insulation impregnated 'with a rather thin liquid, oily and not too resinous mass' with cable joints bound with linen tape first boiled in oil so that it is completely saturated, with the wrapped joint inclosed in a lead sleeve, soldered to the lead sheath of the cable. Through a hole cut in the top of the sleeve or socket 'hot insulating mass is poured into the socket. ”

“ The natural increase in the number of aerial wires created a demand for better insulation and grouping in cables. Hundreds of miles of No. 12 iron wire were braided and dipped in suitable compound for this use. The annoyance from induction soon made a call for anti-induction cable. This want was supplied by a tin-foil cable so called, in which each conductor, after being insulated, was enclosed in a strip of this tin-foil. Cotton-covered wires to the extent of 50 or 100 were cabled together, and after being saturated with paraffine were placed in a lead pipe. ”

“ A piece of iron wire was found to have pierced the cable diametrically, so as to make contact between the sea and the conductor. The faulty portion was cut out, and the paying out resumed as soon as the cable was spliced up again. On July 29th, when 716 miles had been laid, another and more serious fault appeared. The arduous operation of picking up again commenced. After nine hours’ work the fault was safe inboard, and the necessary repair effected. On stripping the cable another piece of iron wire was discovered sticking right through the core. ”

“ The result of this is nowadays to practically double the carrying capacity and earning power of the line, the effective speed in either direction remaining virtually the same as in “simplex” working, provided the cable is in good condition. [73] The armor of this cable (Fig. 43) is also a good example of present-day practise, each wire (usually covered with compounded tape) butting against the next; this is found to be the most durable form for a deep-sea cable.
In 1898 another French Atlantic line of a similar type to the above was laid. ”

“ Intermediate piers support the trusses in the side spans. The cables are 183⁄4 in. in diameter; each weighs about 1116 tons, and has a nominal breaking strength of 22,320 tons, the actual breaking strength being probably greater. The saddles are 332 ft. above the water. The four cables support a dead load of 7140 tons and a live load of 4017 tons. Each cable is composed of 37 strands of 208 wires, or 7696 parallel steel wires, No. 8 B.W.G., or about 3/16 in. in diameter. The wire was required to have a tensile strength of 89 tons per sq. in., and 21⁄2% elongation in 5 ft. ”

“ This was, of course, before the days of cutting and holding grapnels as we now have them, which render it{199} possible for a single ship to effect repairs—even where it is out of the question to recover the cable in one bight.
Fig. 40.—S.S. Great Eastern Completing the Second Atlantic Cable.
Setting to Work: Repeated Failures.—When the Great Eastern arrived on the grappling ground, the Albany (with Mr. Temple in engineering charge) had already hooked and buoyed the cable, but the buoy-chain having been carried away, they not only lost the cable, but 2,000 fathoms of wire rope besides. ”

“ On these principles the core of the new “Commercial” cable was composed of a copper conductor weighing 500 pounds per nautical mile, covered with a gutta-percha insulating-sheath weighing 320 pounds per nautical mile, while the new “Anglo” has a core with conductor weighing 650 pounds per nautical mile, and gutta-percha insulator 400 pounds per nautical mile, involving a completed cable (main type) nearly double the weight of previous corresponding lines. ”

“ Company. The new “Commercial” line was constructed and laid by Messrs. Siemens Brothers, and the “Anglo” cable by the Telegraph Construction Company. Fig. 43 shows the type adopted for the deepest water of the latter, and Fig. 44 that for the shore ends. Here the wires, besides being of a very large gauge, are applied with an extremely short lay (hence the elliptic appearance, though circular in reality) , in order to increase the weight of iron, and thereby avoid shifting and abrasion. This type is now in constant use where rocks, ice-floes, strong currents, or rough weather are experienced. ”

“ Who has not seen men in the streets dragging huge pipes of lead through the open manholes from big wooden spools? These are the cables you talk over. They have been papered and clothed—and tarred and feathered, maybe—and then encased in lead by a process that is so easy as to be laughable, and yet as ingenious as any one thing the wire miller does. Unrolling slowly from its spool, the heavy cable moves up to a machine built strong and four-legged from the floor. ”

“ In 1850 a cable twenty-five miles in length was laid from Dover to Calais, only to prove [Pg 40] worthless from faulty insulation and the lack of armour against dragging anchors and fretting rocks. In 1851 the experiment was repeated with success. The conductor now was not a single wire of copper, but four wires, wound spirally, so as to combine strength with flexibility; these were covered with gutta-percha and surrounded with tarred hemp. As a means of imparting additional strength, ten iron wires were wound round the hemp—a feature which has been copied in every subsequent cable (Fig. 58) . ”