REPAIRING THE COOK’S STRAIT CABLE.

South Canterbury Times, Volume XV, Issue 2065, 5 November 1879, Page 3

REPAIRING THE COOK’S STRAIT CABLE.

Many of our readers may possibly not te aware that the steamer Agnes arrived hero this morning for the purpose of taking on board the spare telegraphic cable at present stored m Wellington, which is required for repairing the Cook s Strait cable, Iho cable about to be shipped is five miles long and has been stored in the tanks on the left-hand side of the wharf since November, 1676. It is the same type of cable as that which now lies stretched from Lyall Bay to White s Bay. It is composed of three wires properly insulated and protected by a stout guttapercha covering. Before the shipment, which is to take place to-morrow, it was accessary to test the cable with a view of ascertaining whether its efficiency had been impaired by its three years storage. The experiments connected with the testing were carried out this morning by Dr Demon, at the telegraph office, by means of a splendid mirror galvanometer (Thomson’s patent,) which is kept for such purposes. The instru-

mentis of a complicated appearance, but • is exceedingly simple in its action. By an ingenious contrivance the amount or resistance to the electric _ current in any wire or cable is ascertained by the deflection of a small flash of light thrown upon a minutely-marked scale, having aero in the centre. The cable in the tank was connected with this machine by two small testing cables stretched across the street into the office window. The result of Dr Demon’s trials this morning was very satisfactory. Dach •Wire of the cable was tested separately, and the following are the comparative tables obtained :-In November, 18/6 i wire, insulation, 404 million units per knot; No. 2 wire,, insulation, 838 da do do; No. 3 wire, insulation, 604 do do do. To-day—No. 1 wire, insulation, 397 million units per knot; No. 2 atid No. 3 wires, insulation, 595 ditto, ditto, ditto, each. This is understood by electricians to show that the cable has not only deteriorated, but has actually improved in its insulation (jnalities since it was stowedaway. iuo

fault in the permanent cable which the spare cable is intended to repair, is said to be about eleven knots from Lyall’s Bay, and involves the present ineffectiveness of two wires out of the three. Besides the five miles which are about to be placed on tho Agness, there are eight miles coiled in an adjoining tank, which will still remain for future service. This also was tested satisfactorily this morning.—“ Wellington Post,” October 16.