History of the Atlantic Cable & Undersea Communications
from the first submarine cable of 1850 to the worldwide fiber optic network
1913 Anglo-Irish Cable
Aber Geirch - Howth 1
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History of the Atlantic Cable & Undersea Communications |
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1913 Anglo-Irish Cable |
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THE NEW ANGLO-IRISH TELEPHONE CABLE The new Irish telephone cable, which is to serve the main trunk route between the southern half of the United Kingdom and Ireland, is the longest submarine loaded cable yet laid by the Department. Its total length is approximately sixty-four nautical miles, being thus some sixteen nautical miles longer than the Anglo-Belgian cable, which was laid in 1911. In several respects the two cables are similar in construction; the dielectric in each consists of the specially treated gutta-percha patented by Messrs. Siemens. They are both loaded on the transformer and phantom circuits, with coils spaced one nautical mile apart; the 7-wire copper strand forming each of the four conductors weighs 160 lbs. per nautical mile, and the dielectric 150 lbs. in both cases. The over-all weight of the completed cable is some 121 tons per nautical mile. Where the coils come in, the cable is strengthened by extra sheathing for about 92 feet. The following are the particulars:
A special feature of this cable is the provision of a fifth core of 50 mils copper G.P. insulated, which runs in the centre for half a naut. at each end of the cable. It is then brought out by means of an insulated iron strand, which is bound in and soldered to the sheath. This wire has been provided as an earth wire in connection with experiments on single-wire submarine telephone cables which are at present being conducted. The object of the length of half a naut. is to permit of the earth wire being taken out to sea and soldered to the sheath, so as to avoid the inductive disturbance which is generally found, to a greater or less extent, when earths are made in a cable hut, especially when telegraph cables are terminated in the hut. The value of the attenuation constant Beta was specified not to exceed .016 per naut. when the transformer circuits and superimposed circuit were tested with a sinusoidal electro-motive force, having a periodicity of 800 per second, applied directly to the end of the cable, and producing one milliampere at the sending end. The results obtained on the completed cable were as follows. A “Franke” machine was used for the tests.
SECTION OF NEW ANGLO-IRISH TELEPHONE CABLE. FULL SIZE. TRANSFORMER CIRCUIT.
The transformer circuits (the two diagonal pairs) have thus a standard cable equivalent of approximately nine miles. The efficiency of the coils is such that, when taken separately, the ratio of the effective resistance (R) to the inductance (L) in each The constants of the completed cable per naut. loop are as follows.
Overhearing was specified on the completed cable between either of the transformer circuits and the superimposed circuit to be not greater than would be observed in direct speech over 65 miles of standard cable having a resistance of 88 ohms per mile loop and a wire-to-wire capacity of .054 microfarads. The figure of 65 miles was stipulated because a similar result was obtained in the Anglo-Belgian cable, and it was feared that a higher figure could not be guaranteed. The copper conductors are of 100 per cent. conductivity to E.S.C. standard for annealed high-conductivity copper. The sheathing wires, fourteen in number (with an additional 3-wire strand to indicate that the cable is a loaded one, are made of the best selected ball furnaced “all wire” pig iron, specified to have a strength not less than 23 tons per square inch and well galvanised with zinc spelter. Experience has shown that iron of this type is less subject to corrosion than the homogeneous iron which was formerly used by the Post Office. Each completed set of loading coils, with their insulated covering and before jointing into the cable, was subjected to an external hydraulic pressure of 15 cwt. per square inch for not less than half an hour without producing distortion or other injury. The cable was constructed by Messrs. Siemens Bros. in their works at Charlton, Woolwich. Aërial land lines of 600 lbs. copper have been run from the respective landing points to Manchester and to Dublin in order to secure a high standard of speech on the circuits. A description of the laying of the cable will appear in our next issue. J.G.H. ANGLO-IRISH (LOADED) TELEPHONE CABLE In the last issue of the Journal there was an article giving the electrical data and details of the construction of the new loaded cable recently laid between Nevin and Howth, and the following notes on the laying operations will probably be of interest. A view of H.M.T.S. “Monarch” is given in the frontispiece. The “Monarch” not being large enough to take the whole sixty-four nauts on board, the cable had to be laid in two halves. The shipment of the first half of the cable from the works of Messrs. Siemens Bros., Woolwich, to the “Monarch” commenced on the evening of October 29th last, and finished on November 1st. On October 31st Sir A.F. King paid a welcome visit to see the cable being taken on board, and he also made a survey of the ship. Late in the afternoon of Saturday, November 1st, the “Monarch” left the Thames for Nevin on the North Wales coast. On Sunday morning, owing to a strong south-westerly gale and a very rough sea, the vessel had to be anchored off Deal for four hours before the conditions moderated sufficiently to allow the voyage to be continued. During Sunday night the wind and sea again increased, and the ship, heavily laden as it was, encountered such bad weather that progress was very slow, a speed of only three knots, as against the usual ten knots, being obtained. The bad weather conditions prevailed until the “Smalls” was passed, and the passage consequently occupied more than double the normal time, the Abergeirch Hut (shown in 1) not being sighted until daybreak on November 6th.
On this date the weather was comparatively calm, and it seemed as though the luck had turned, a good day’s work being done. Six buoys, to indicate the correct route for the cable, were placed at intervals of about five nautical miles, and in addition a “mark” buoy inshore and one beyond the outermost buoy were also placed. Early on the morning of the 7th the “Monarch,” lying about half a mile off the coast, sent the steam launch ashore for the writer and Messrs. Dieselhorst and Dyke, the representatives of Messrs. Siemens Bros. It was soon evident, however, that the luck had again turned against Mr. Pollard, the sea, breaking roughly on the shore, making it impossible to land the cable end. It was therefore decided to steam along the proposed course to check the line of buoys and renew the oil in the lamps on the outer buoys, which had to be lighted as a guide for the ships passing north and south. The recharging of the lamps during a rough sea appears to a layman to be a risky operation. 2 shows the work being done at one of the buoys.
The bad weather which continued during the three following days prevented a start being made with the cable-laying, and it was not until the 11th that the conditions moderated sufficiently to allow the landing operations to be carried out. At four in the morning the “Monarch” anchored off the landing place, the shore end was transferred to a raſt consisting of two large lifeboats, and the cable paid out. Before eight o’clock this work was completed, and the “Monarch” immediately proceeded to sea, paying out at the rate of five knots. During the morning the wind increased to a gale of exceptional violence and the sea became very rough, making the task of cable-laying no light one. The outer end of the Welsh half of the cable is laid at the deepest part of the channel (70 to 80 fathoms), and the ship becoming lighter and lighter in draught as the paying out proceeded, the utmost difficulty was experienced in keeping the ship to the course during the laying of the last six miles of cable. In 3 a loading-coil is seen passing out at a speed of five knots. 4 shows the cable passing over the bow, the list of the vessel giving some idea of the weather conditions. There was a feeling of great relief when, at about three o’clock in the afternoon, the cable end was passed out and buoyed.
The “Monarch” immediately proceeded to Holyhead, and was compelled to lie there for nine days, during which time the weather conditions were too bad to allow the buoys to be picked up. As there appeared no prospect of the weather improving, it was eventually decided to leave the buoys and return to Woolwich for the second half of the cable. During the stay at Holyhead the “Monarch” shipped sixty tons of coal in twenty minutes from the L. & N.W. Railway Company’s special mechanical loading collier, see 5. This collier is capable of coaling the Company’s steamers, for which work she was designed, at the rate of three and a half tons per minute.
It will be readily understood that the strain on the officers and crew had been very great indeed, and it was necessary, much to the regret of all on board, to land at Rosslare the popular chief navigating officer (Mr. Broadbridge) suffering from a serious nervous breakdown. Woolwich was reached on November 24th, and three days later the “Monarch” left for the cable ground with the second half of the cable. The buoys on the Welsh side were picked up, and on December 1st the second series were placed in position on the Irish side. The Engineer-in-Chief joined the ship on that date to see the second half laid, but the weather was so very bad on the five following days that cable-laying was impracticable. It was not until Sunday, December 7th, that the Irish end could be landed at Howth. 6 shows the landing place, the Martello tower seen in the photograph being used as a cable hut.
The “Monarch” left Kingstown at three in the morning, and after landing the shore end, the laying of the second half commenced shortly after nine, the buoyed end of the first half of the cable being reached about 3.30. It was then found that the cable was short by about two hundred yards, and efforts were made to pick up the slack on the Welsh side until darkness prevented further operations. The ship was kept close by the buoy all night in order to continue the operations at daybreak. Unfortunately on the following day the weather was again stormy and the greatest difficulty was experienced in handling the ship relieved of its cargo. Bad weather continued for several days, and when at last it was possible to proceed with the operations a fault was discovered on the Irish side. The cable had been mechanically damaged by fouling something on the sea bottom, resulting in the cores being crushed. Owing to the weather conditions, considerable difficulty was experienced in picking up and relaying the cable, and it was not until 9.15 p.m. on December 13th that the last splice was completed and slipped overboard. At 10.15 p.m. the very welcome report was received from the testing officers at Nevin that the cable tested satisfactorily. Thus ended one of the most arduous operations ever undertaken by the Department’s Submarine Staff. During the whole period of the Commission every conceivable difficulty had been experienced; the few hours of daylight, the persistent bad weather and rough seas, the exceptional difficulties in landing, and, finally, the damage to the cable in mid-channel all contributed to throw a severe strain on the staff, and it is impossible to speak too highly of the zeal and esprit de corps of all the officers and men under the command of Mr. Pollard during a time of unparalleled difficulty, not to say of danger. It must be remembered that the “Monarch” is essentially a cable-repairing vessel and is only equipped with the necessary picking-up gear; and in consequence the cable had to be paid out over the bow sheave. The experience gained during the laying of the Anglo-French and Anglo-Belgian cables warranted the assumption that the ordinary equipment of a cable-repairing vessel was sufficient for any emergency which might arise during the operation of laying. The fact that the laying of this Irish cable was successfully carried out by the “Monarch,” notwithstanding the severe and adverse conditions, clearly demonstrates that this type of coil-loaded cable can be handled in the same way as any other type of submarine cable. The necessity for picking up and relaying a portion of the cable, to which reference has already been made, resulted in some variation and irregularity in the spacing of some of the loading coils; in fact circumstances occurred which would be expected to arise during the course of an ordinary repairing operation. It should be noted, however, that this alteration in the spacing of the loading coils was not accompanied by any appreciable change in the electrical values of the cable. The cable has been working continuously since completion, and the tests indicate that it is in perfect condition. W.N. The Times December 30, 1913 The laying of the new telephone cable between Nevin, in Carnarvonshire, and Howth, near Dublin, a feat which has just been accomplished by the Post Office cable ship Monarch during heavy weather, has made a notable addition to the telephonic facilities between England and Ireland. Until the present time the only cable available for telephonic traffic to Ireland has been that between Port Mora, near Portpatrick, and Donaghadee. This cable, which has been in service since 1893, is nearly 24 nautical miles in length, and is of the same type as that which was laid between Dover and Calais in 1891. Up to a comparatively recent date there were technical difficulties in the way of providing telephone cables except over narrow arms of the sea, like the Straits of Dover or the Stranraer-Larne route. The result has been that communication between England and Ireland was only possible over land lines through Carlisle, thence to Port Mora, by cable to Donaghadee, and south by land lines from Belfast. During recent years the design of submarine telephone cables has improved to the point where it was found possible to lay one between St. Margaret's Bay and the coast of Belgium, and the successful working of that cable led to the decision to provide for direct telephonic communication with Dublin. The cable which, in pursuance of this policy, has now been put in service has a total lengtlh of 64 nautical miles (nearly 74 miles), and is the longest submarine telephone cable which has yet been laid. It was manufactured by Messrs. Siemens Brothers and Co., and is of the four-core Pupin-loaded design, this being the method by which satisfactory submarine transmission is made possible over any considerable mileage. |
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Last revised: 1 January, 2021 |
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