VOICE UNDER THE SEA.

Auckland Star, Volume LVI, Issue 180, 1 August 1925, Page 16

VOICE UNDER THE SEA.

ROMANCE OF THE CABLES. I THE MARCH OF WIRELESS. NOT FEARED BY THE CABLES. The electric spark is the life of trade. Further evidence of the cable companies' confidence that there is at present little to fear from wireless competition, is j afforded by the decision of the Pacific Cable Board to duplicate tbe line across the Pacific. This is tbe Suva (Fiji) — Fanning Island —Vancouver route, a distance, roughly, of 5500 miles. The contracts have been let to the Telephone Construction Company and Siemens Bros., and the work is expected to be completed by August or September next year. With this cable, which will embody all the latest improvements, it is expected a transmission speed of 1700 letters a minute will be obtained. Despite the onward march of wireless the pulse still beats along the ocean bed where lie tlie great cables. ' Linking continent with continent, crus.ted with barnacles, weed, sponge and coral, they criss-cross the sea floor in slimy ooze and weed-decked submarine grotto and daily over their thousands of miles flash messages of love and hate, sorrow and joy, tidings of commerce and finance and the work-a-day. world. There is no sea-girt country in the world to-day but a thin wisp of cable rises from the waves lapping her shores and renders impotent the dividing seas. No discovery of modern times save wireless, yet in its infancy, has done so much to annihilate space and promote the welfare of mankind as the cables. The birth of the cable dates back 75 years. In 1851 the first commerciallysuccessful cable was laid across the Strait of Dover from the South Foreland to Sangatte (France) by T. R. Crampton. Two years later, after a number of futile attempts, another was laid between Port Patrick, in the south of Scotland, and Donoghadee, in Ireland. These successes set the hearts of engineers a-burning for further triumphs, and it, was only five years later that, after heartbreaking failures due to breaking cables, the first Atlantic cable was laid by the British warship Agamemnon and the American warship Niagara. From that date, 1856-1857, the pioneers of the cable never looked back. To-day the cables in existence on the ocean floor could gird the earth a dozen times. Sir John Pender, who died in 1896, contributed most to the development of this great industry. His son, Sir John Denison-Pender, to-day controls.the destinies of the great Eastern and associated cable companies whose cables poke their shore ends into nearly every sea-girt country in the world. The development of the cables is a romance in itself. A Fight Against Nature. In the early days imperfect knowledge of the sea floor was responsible for many failures. Cables were often laid in ignorance over uncharted submarine gul-. lies, and broke with the strain of sus- | pension. Mankind had to fight Nature. Seismic disturbances and consequent shiftings of the ocean bed were a cause of many ruptures. Over these man had no control, but the mo>st deadly foe at the beginning was a tiny seaworm—the teredo. The teredo bored into the cable through the gutta percha covering, penetrated between the sheathing wires, and reached the core, thus allowing water to infiltrate and interfere with the insulated wire, with a consequent interruption and breakdown of the service. Some I means had to be found of checking the I depredations of this tiny foe and experiI ments resulted in the perfected cable of to-day. The core of the modern cable—over which the messages are flashfed—!&_ a copper conductor surrounded by seven thin copper wires, which have been em- | bedded in hot gutta percha. This in • turn is sealed with a brass tape. Over this is wound a layer of jute yarn steeped j in tarry preservative, then comes a layer I of galvanised iron sheathing wires, also I with a tar protection; these 5 are cov-'. j ered with a further serving of and I the whole is thickly coated with Stockholm tar. I It was the introduction of the brass ! tape that foiled the little teredo. Heavier armour is necessary in shallow waters near the shore, owing to the wear and tear of the water's motion an d the destructive action of the iodine in the seaweed. Near the shore the cables may be three inches thick; in the' ocean depth's the average is one inch. The most modern cables are built on these lines, and can carry 600 letters a minute transmitted simultaneously from each end, or~ a full capacity of 1200 letters a minute. Specially-constructed ships are employed for laying the cable. The vast | lengths of When ready for depositing on the ocean bed, are coiled in horizontal flakes in water-tight tanks in the cable ship. Each nautical mile of cable is marked in manufacture. Landing the Cable. 1 The ship is then navigated to the place where the shore end is to'be landed. Sufficient cable to reach the cable house ia then paid overboard on to a raft, the end taken to the cable house and there tested. The ship then steams slowly off, paying out the cable,.over the stern. Special apparatus controls the speed of the cable as it leaves the ship, and checks the length paid out. This is also checked by the miles marks on the cable itself. In these days the route, of course, is pretty well surveyed, and there is little danger of dropping the cable into some submarine chasm with a consequent breakage owing to the strain of suspension. In laying the cable ample slack is provided for all eventualities. In some cases this amounts to ten per cent of the estimated length of cable required by the chart. No less interesting is the method of repairing breaks in the cable and of renewing worn parts. When a break occurs, so perfect is the modern telegraphic mechanism that by a simple electrical test from both shore ends of the cable the approximate position, of the fracture can be determined, with a probable error not exceeding three or four miles. ' Apprised of the approximated position of the break, the captain of the repair ship proceeds to the spot and lowers one '| or perhaps two marked buoys. A grapnel, a species of five-pronged anchor, attached to a rope of steel and manila, is then lowered to the bottom and dragged at a slow speed in a line at right angles to the cable route, until the behaviour of the dynamometer, on which the action of the grapnel is registered, . shows that the cable is hooked. The- ship is then stopped, and the | cable is hove to the surface, an electrical test is applied, and the distance away of the broken end is determined. This gives I an excellent idea of the location of tbe

other broken end, and, after buoying the retrieved cable, the ship proceeds to the spot and grapples ' for the other half of the broken cable. This, also, when found, is buoyed. The ship then returns to the original spot, brings on board the broken end, and secures com- ; munication with the shore. The gap between the broken ends has now to be closed, and this is effected by splicing on a new cable, which is paid out until the other buoy is reached,and the other broken end recovered After the final splice is made the cable is slung on a slip-rope and lowered overboard, sinking by its own weight to the sea-bed. The buoys are picked up, and the ship returns to port. Specially Equipped Steamers. The cable companies have their own specially equipped steamers. These now number 40, ranging in size from 300 tons to 10,000 tons carrying capacity. In the case of the Eastern Extension, whose, "sea territory" commences at Madras (India), and includes China, Australia and New Zealand, three cable repairing vessels are stationed at Singapore. The success of the repair naturally depends on quiet conditions of sea and weather. Interference of heavy weather in a half-completed job frequently means that the whole series of operations has to be done over again. One cable repair cost £75,000. This was a break between Aden and Bombay, in a depth of 1900 fathoms. Tho repair was effected with the expediture of 176 miles of new cable. The operation took 251 days —103 days of active work, the remainder being interrupted by the monsoons. A repair to the Lisbon-Porthcurnow cable, broken in the Bay of Biscay in a depth of 2700 fathoms, took 215 days, and 300 miles of new cable. In shallow waters and under favourable . conditions, however, the repairs usually take but a few hours. The life of a cable depends largely on where it is placed. In depths beyond the reach of wave motion it naturally has a much longer period of usefulness— sometimes 40 years—than in shallower water or places subject to ptrong tidal action. Cables have been found worn almost to needle thickness. Some queer things are fished up with the cables. Always they are coated thickly with seaweed and marine growths, and oysters and large shells are frequently found adhering to. the strand. A grisly object met the eyes of the crew of a repair ship once when the ribs and trunk bones of what was apparently the skeleton of a man slung on the cable was brought to light when the grapnel hove the bne to the surface. Instances are recorded in-which marine monsters have made a vicious snap at the cable and effected damage which entailed a costly repair trip. In the cable between. Java and Port lifted for repairs, a huge tooth, bigger than a shark's, was found stuck in the damaged cable—relic of an attack by some creature of the underseas yet unknown to man. j Though constant strides are being made in the development of wireless, the cable continues as the foremost medium of inter-continental communication. In the last 12 months no less than 26,000 miles of cables have been contracted for by one large company alone. These include the Government Pacific cable from Canada to Australia, the Italian Cable Company's cable from Italy to the Azores and South America, and the Western Union Company's cable from U.S.A. to Great Britain.