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Story of the Atlantic Cable

<h3>CHAPTER IV PREPARATIONS FOR ANOTHER ATTEMPT</h3> <div class="blockquot">“Taking Stock”—Further Capital—Alterations in Paying-Out Machinery—Improved Testing and Signaling Apparatus. </div> THIS untoward interruption to the expedition was naturally a cause of great disappointment to all connected with the undertaking; for there was not enough cable left to complete the work, nor was there time to get more made and stowed on board to renew the attempt before the season would be too far advanced. The squadron proceeded to Plymouth to unload the cable into tanks at Keyham (now Devonport) Dockyard, chiefly because some of the ships could not be spared by their respective governments till the following year. In the middle of October (1857), the engineer-in-chief proceeded to Valentia in a small paddle-steamer with the object of picking up some of the lost line from this end. After experiencing a series of gales, over fifty miles of the main cable were recovered, and the shore end buoyed ready for splicing on to in the coming year. The first expedition had opened the eyes of the investing public to the vastness of the undertaking, and led many to doubt who did not doubt before. Some began to look upon it as a romantic adventure of the sea, rather than as a serious commercial{75} undertaking. This decline of popular faith was felt as soon as there was a call for more money. The loss of 335 miles of cable, with the postponement of the expedition to another year, was equivalent to a loss of £100,000. <ANTIMG class="enlargeimage" src="images/enlarge-image.jpg" alt="" width-obs="18" height-obs="14" /> <ANTIMG src="images/ill_pg_075_sml.jpg" width-obs="250" height-obs="178" alt="Fig. 15.—Reshipment of the Cable aboard H.M.S. Agamemnon and U.S.N.S. Niagara in Keyham Basin." /> Fig. 15.—Reshipment of the Cable aboard H.M.S. Agamemnon and U.S.N.S. Niagara in Keyham Basin. Raising Further Capital.—To make the above sum good, the capital of the company had to be increased, and this new capital was not so readily obtainable. The projectors found that it was easy to go with the current of popular enthusiasm, but very hard to stem a growing tide of popular distrust. And it must also be remembered that, from the very first, the section of the public which looked with distrust upon the idea of an Atlantic telegraph was far in excess of that which did not; indeed, the opposition encountered was much on a par with{76} the great popular prejudice which George Stephenson had to overcome when projecting his great railway schemes. But whatever the depression at the untimely termination of the first expedition, it did not interfere with renewed and vigorous efforts to prepare for a second. In the end the appeal to the shareholders for more money was responded to; and the directors were enabled to give orders for the manufacture of 700 miles of new cable of the same description, to make up for what had been lost, and to provide a surplus against all contingencies. Thus, 3,000 nautical miles in all were shipped this time, instead of 2,500 miles. Alterations in the Paying-Out Gear.—New paying-out machinery was devised with a view to obviating the possibility of a recurrence of the accident on the first expedition. In the new apparatus the brake (Fig. 16) was so arranged that a lever exercised a uniform holding power in exact proportion to the weights attached to it (Fig. 17); and while capable of being released by a hand-wheel, it could not be tightened. The general idea of this clever appliance had been originally introduced by Mr. J. G. Appold in connection with the crank apparatus in jails; and it was now especially adapted to the exigencies of cable work by the engineer (Mr. Bright) and Mr. C. E. Amos, a member of the famous engineering firm, Easton & Amos, who constructed the entire machinery. The great future of the apparatus was that it provided for automatic brake-release, upon the strain exceeding that intended. Thus, only a maximum agreed strain could be applied, this being regulated from time to time by weights, according{77} to the depth of water and consequent weight of cable being paid out. In passing from the hold to the stern of the laying vessel, the cable is taken round a drum, or drums. Fig. 18 gives a general view of the apparatus. Attached to the axle of the drum is a wheel fitted with an iron friction-strap (to which are fixed blocks of hard wood) capable of exerting a given retarding power, varying with the weights hung on to the lever which tightens the strap. When the friction becomes great, the wheels have an increased tendency to carry the wooden blocks round with them; thus the lever-bars are deflected from the vertical line and the iron band opened sufficiently to lessen the brake-power. <ANTIMG class="enlargeimage" src="images/enlarge-image.jpg" alt="" width-obs="18" height-obs="14" /> <ANTIMG src="images/ill_pg_077_sml.jpg" width-obs="247" height-obs="221" alt="Fig. 16.—The Self-Releasing Brake." /> Fig. 16.—The Self-Releasing Brake. {78} <ANTIMG class="enlargeimage" src="images/enlarge-image.jpg" alt="" width-obs="18" height-obs="14" /> <ANTIMG src="images/ill_pg_078_sml.jpg" width-obs="273" height-obs="117" alt="Fig. 17.—The Principle of the Brake." /> Fig. 17.—The Principle of the Brake. Bright also introduced a dynamometer apparatus for indicating and controlling the strain during paying out—a vast improvement on that embodied in the previous machines. The working of the entire machine was as follows: “Between the two brake-drums and the stern of the vessel, the cable was led under the grooved wheel, O, of the dynamometer. This wheel had a weight attached to it, and could be moved up or down in an iron frame. If the strain upon the cable was small, the wheel would bend the cable downward, and its index would show a low degree of pressure; but whenever the strain increased, the cable, in straightening itself, would at once lift the dynamometer-wheel with the indicator attached to it, which showed the pressure in hundredweights and tons. The amount of strain with a given weight upon the wheel, G, was determined by experiments, and a hand-wheel in connection with the levers of the paying-out machine was placed immediately opposite the dynamometer; so that, directly the indicator showed strain increasing, the person in charge could at{79} once, by turning the hand-wheel, lift up the weights that tightened the friction-straps, and so let the cable run freely through the paying-out machine. Although, therefore, the strain could be reduced—or entirely withdrawn—in a moment, it could not be increased by the man at the wheel. The cable in coming from the tanks, passed under a lightly weighted ‘jockey,’[22] J, pulley. This arrangement, while leading the line on to the drums, at the same time checked it slightly. From here it was guided by a grooved pulley, or V-sheave,[23] L, along the tops of both drums, at B, then three times round them, and hence over another V-sheave, F, and on to the dynamometer. From this the cable was led over a second pulley, and so into the sea by the stern-sheaves.”[24] This entire apparatus—simplified as regards the brake—has since been universally adopted for submarine-cable work,[25] with the exception that a single-flanged drum, fitted with a sort of plow, skid, or knife-edge—to guide or “fleet” the incoming turn of cable correctly on to the drum—is now used in place of the grooved sheave, or sheaves. As soon as the new machinery was constructed, all the engineering staff gathered together for the purpose of thoroughly acquainting themselves with its working. Mr. F. C. Webb, having engagements elsewhere, had been replaced by{80} Mr. W. E. Everett, U.S.A., who had been chief marine engineer of the Niagara. Mr. Everett was to have charge of the machinery on the laying vessel, while Mr. Woodhouse controlled the cable operations. <ANTIMG class="enlargeimage" src="images/enlarge-image.jpg" alt="" width-obs="18" height-obs="14" /> <ANTIMG src="images/ill_pg_080_sml.jpg" width-obs="324" height-obs="116" alt="Fig. 18.—Bright’s Paying-out Gear, 1858." /> Fig. 18.—Bright’s Paying-out Gear, 1858. Alterations in the Electrical Apparatus.—Since the manufacture of the cable in 1857, Professor Thomson had become impressed with the conviction that the electric conductivity of copper varied greatly with its degree of purity. As a result of the professor’s further investigations, the extra length of cable made for the coming expedition was subjected to systematic and searching tests for the purity and conductivity of the copper. Every hank of wire was tested, and all whose conducting power fell below a certain value rejected. Here, then, we have the first instance of an organized system of testing for conductivity at the cable factory—a system which has ever since been rigorously insisted on. Professor Thomson’s Mirror Instrument.—And now, in the spring of 1858, an invention was perfected that was destined to have a remarkable effect on submarine-cable enterprise. For Professor Thomson (now Lord Kelvin) devised and perfected the mirror-speaking instrument, then often described as the marine galvanometer,[26] of which it may be fairly said that it entirely revolutionized long-distance signaling and electrical testing aboard ship.{82} This most ingenious apparatus consists of a small and exceedingly light steel magnet (a) (Fig. 19) with a tiny reflector or mirror fixed to it, both together weighing but a single grain or thereabouts. This delicate magnet is suspended from its center by a filament of silk and surrounded by a coil (b) of the thinnest insulated copper wire. <div class="figleft"> <ANTIMG class="enlargeimage" src="images/enlarge-image.jpg" alt="" width-obs="18" height-obs="14" /> <ANTIMG src="images/ill_pg_082_sml.jpg" width-obs="86" height-obs="87" alt="Fig. 19.—The Reflecting Magnet." /> Fig. 19.—The Reflecting Magnet.</div> A very weak current is sufficient to produce a slight, though nearly imperceptible, movement of the suspended magnet when electricity passes through the surrounding coil. A fine ray of light from a shaded lamp, behind a screen (Figs. 20 and 21) at a short distance, is directed through a slot in the screen, thence to the open center of the coil (c) upon the mirror. It is then reflected back to a graduated scale (f). As may be seen from Fig. 21, an exceedingly slight angle of motion on the part of the magnet (a) is thus made to magnify the movement of the spot of light upon the scale (f), and to render it so considerable as to be readily noted by the eye of the operating clerk. The ray is brought to a focus by passing through a lens. By combinations of these movements of the speck of light (in length and direction) upon the index, an alphabet is readily formed. The magnet is artificially brought back to zero with great precision after each signal by the earth’s magnetism, and also both by the natural torsion of the fiber and the controlling action of the adjusting magnet (e) (Fig. 20), with the{83} help of the thumb-screw (d) for regulation purposes. <ANTIMG class="enlargeimage" src="images/enlarge-image.jpg" alt="" width-obs="18" height-obs="14" /> <ANTIMG src="images/ill_pg_083a_sml.jpg" width-obs="279" height-obs="151" alt="Fig. 20.—Reflecting Galvanometer and Speaker." /> Fig. 20.—Reflecting Galvanometer and Speaker. In a word, Professor Thomson’s combined mirror-telegraph and marine galvanometer transmitted messages by multiplying and magnifying the signals through a cable by the agency of imponderable light. <ANTIMG class="enlargeimage" src="images/enlarge-image.jpg" alt="" width-obs="18" height-obs="14" /> <ANTIMG src="images/ill_pg_083b_sml.jpg" width-obs="275" height-obs="99" alt="Fig. 21." /> Fig. 21. It is only to be regretted that the electrician responsible for the subsequent working through operations did not sooner appreciate the great beauties of the above apparatus, and the advantage of a small generating force such as it alone required.{84} <div style="break-after:column;"></div>

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