PACIFIC CABLE

New Zealand Times, Volume L, Issue 11497, 18 April 1923, Page 3

PACIFIC CABLE

THE DUPLICATION PLANS £300,000 CABLE SHOULD BE T.Am BY AUGUST. “SURVEY MOST SATISFACTORY.” (Special to “New Zealand Times ”) AUCKLAND, April 16. By the middle of neat April the Pacific Cable will be duplicated between Auckland and Suva and between Sydney and Southport (Brisbane), and users will know that in the event of a break on the southern triangle fanned by Sydney, Suva, and Auckland, there aie now ample alternative routes to make it practically certain that total interruption in the triangle will be impossible. From Auckland, for instance, we can get through to Sydney direct, via Norfolk Island and (when the new line is laid) through Fijij chitting dSit Norfolk. H.M. cable ship Iris returned to her moorings off Devonport after four weeks’ surveying, etc., in connection with the new cable, and as usual Captain W. St. Holmes brings in the shin in epic and span order. Leaving Auckland on the 20tjh of last month, Hie Iris carried out the important work, of locating the route o\er which the duplication will be laid. As .everyone with any knowledge of submarine cables knows the cable is not simply paid out over the stem and left to its own .sweet devices in the matter of finding a lodgment on the bottom of the sea. The route hae to be known to a nicety. For instance, there may be a “deep” between two comparatively close ridgew, and if due allowance were not made for the hollow the cable would be swinging free between the two ridges—a fatal condition for a submarine'cable. Then, again, on a rooky bottom a cable would soon chafe itself away, so a suitable “oozy” route must be found It is interesting to know that the Auokland-Suva duplication will lie in a snug bed of globergina ooze, which practically acts as a preservative for the cable.

DEEP-SEA SOUNDING. In order to ascertain not only the depth of the ocean along the route but to find out what sort 1 of a bottom there is, an ingenious apparatus known as Lucas’ patent ie used on such a trip as that of the Iris. A heavy weight is attached to piano wir4whuving a breaking strain of 2701 b. sVhen tbe , bottom* is reached the weight is automatically released, and what is known as the lead “snapper” grabs a little sample of the bottom, which is duly examined and its nature recorded whew the wire is wound on board again. For the purpose of ascertaining the temperature away down at the depth at whiohi the Pacific cable lies, a ther- I urometer is attached to the sounding wire, and people not familiar with oceanography will he surprised that • down in the dark and Kmely neighbourhood of 2000 fathoms the mercury ahowes 34 degrees Fahrenheit, only two degrees above freezing point.* OVER TWO MILES DEEP. A depth of 2300 fathoms—just about two miles and a half—was the deepest spot the Iris found on the duplication route. Soundings every twentyfive miles or so were taken on the I voyage up, and every time a sounding is taken the ship is astopped, so the work takes some considerable time. The Lucas sounding machine is an ingenious piece of mechanism, and the paying out and binding in of the thin piano wire can be regulated to a nicety. Power is, of course, used, and although it is possible to pay out ns much as 100' fathoms per mmuto, the actual time it takes foe the weighted wire to Teach the bottom in say. a "deep” where the bottom is well over two _ miles from the surface' of the water is considerable, and the first time you watch the whizzing wire paying out minute after minute, you are not surprised that tbe ancients believed that there were such things as bottomless pools and oceans. At Suva the Iris did some surveying work at the eastern entrance through the reef in Lauoala Bay, through which it is intended to lay the duplication instead of through the, usual steamer entrance to the westward. “A VERY GOOD ROUTE.” ' MrNjohn Milward, the manager of the Pacific Cable, , came ■ down from Suva in the Iris, and interviewed, Said the result of the survey was most satisfactory. The bottom was an excellent one for the cable, and the/route would be good in every way. The , stretches '■■ that were being duplicated, said Mr ' Milward, were from Sydney to Southport (near Brisbane) 600 miles, and from Sava to Auckland direct, 1200 mile*. The cost of the work will be £300,000, and both' cables' should be laid by August 14th next, possibly earlier. The Telegraph Construction and Maintenance Company, which Betmred Hie contract, is a well-known British ro npany, and the cable was manufactured at Greenwich. ,It is .interesting to know Hiat tbe steamer to be used, ti e Stephen, a vessel of 4636 tons, was formerly a German cable ship, and was handed over in connection with the reparation settlement. She .is much smaller than the big cable ship Oolon'a, the 8000-tonner that was used in laying te main .part of the original cable. The past year was a wonderfully bvsy one for the Pacific'Cable, and when he was asked if the duplication would increase the capacity, Mr Milward said -it would not for the, moment, as the question of the duplication beyond Suva,' through Fanning Island to Canada, was in abeyance, but the duplication would ensure* an absence from interruption from Fiji downwards. EXPERIMENTAL CABLE. Explaining why the longer duplication Was in abeyance, Mr Milward said' experiments were being carried out with a new design of submarine cable, technically known as the “continuous load cable.” the .practical result of which would he (if successful) that the cable would carry eight times as much work ar> at present. A length of this cable was being manufactured, i.d the board' hoped' that within six montns they would be able to speak definitely about the results of the experiment. Referring to the wireless experiments the board was reported to be making, Mr Milward said they had nothing to do with the question of duplication. While the hoard was waiting for the result of the “continuous load cable,” it was using the interval to carry on experiments in wireless both in Fiji and Canada. Mr Milward will spend eome days in Auckland attending to board business, at the end of which he will return to Sydjjey. ■’