REPAIRING THE CABLES

Hokitika Guardian, 30 August 1926, Page 1

REPAIRING THE CABLES

(By a Marine Engineer). It is not generally known that the recent earthquake shocks, as far apart as Germany and Java, Egypt qnd South Africa, have caused grave concern to the chief electricians of cable companies. • For with these seismic disturbances usually come disturbances in the bed of the ocean and the snapping of submarine cables. The first indication that a cable is broken is the failure of tlie receiving apparatus to record the incoming signals. Cables are interrupted either by the complete severance of the cnductor (or core or by leakage in the insulation or covering). When the cable operator detects that there is something amiss, the electrician is called and immediately makes the “test” whereby it is possible to find almost the exact position of the fault. The test is ns follows: The resistance per nautical mile of the cable is notified to the cable company at the time it is handed over by the makers. Supposing the resistance is two ohms ■perinalo and the testing instrument indicates the resistance of the broken cable to be 800 ohms, the position of the break would bo 400 miles from shore. With this information, together with his charts, the captain of the cablerepairing ship is able to proceed to within a. .very short distance of the break. There, with grapnels, he drags the bed of the ocean in a zig-zag course until he hooks the cable. The broken end of the cable is then slowly hauled on board and communication established between the ship and the cable station on shore. The end is fastened 'to a buoy and the cable ship grapples for the other end. When this is found it is taken on l>oard and joined up to the end fastened to the buoy. , Some idea, of the difficulties which attend the laying of a cable across the Atlantic or Pacific may he gathered from the fact that when a cable ship recently put down 900 miles of her cargo in the deepest part of the Atlantic, known as “Telegraph Plateau.” two and a half miles under water, the cable snapped, and it was mjany days

before it was recovered. Repairing a cable is sometimes an expensive business, ns it can only be successfully accomplished in calm weather. One job in .mid-Atlantic cost no loss tiffin £95,000.

The life of cables varies considerably, according to the nature of their bed. There are cables in the North Rea to-day more than 60 years old which are working as efficiently as on tho Say they were bid, and one of the Transatlantic cables between this country and the United States laid in 1873 is still in order. On a rocky lied a cable would last a mere fraction of this time.