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[Page 37]
In the early spring of 1918 the hunting and harrying of Fritz in the Adriatic had become, from Frit's point of view, most thorough and intense. From merely pottering up and down looking out for periscopes or other signs of our subaqueous enemy, and fervently despised foe, we had adopted entirely new tactics.
First of all "Torrens" came up from Malta fitted with no less fewer than three different types of hydrophones, the principal of which, and the one from which great things was were hoped being the Nash "Fish" hydrophone.
The "Fish" Hydrophone
This was an extremely ingenious and under certain conditions an effective means of detecting and locating foe within killing distance. the by now universal foe, and merits a few words of description It comprised a cylindrical wooden vessel about 14 ft long, tapered at both ends (cigar shape) and covered with very thin strips of German nickel and fitted at at its stern with four fixed hydroplanes - two vertical and two horizontal, to help steady it in the water. was the outward appearance of the "fish' itself. Inside, situated some thirty inches from ether end, were located two very sensitive microphones. Into the nose of the "fish" a twenty-eight wire core insulated cable was fitted and connected with the microphones.
Into the nose of the "fish" a twenty-eight wire core insulated cable was fitted and connected with the microphones. This cable, when not in use, was kept on a small hand winch, the other end of it being led along beneath the upper deck to a switch-board in a silence cabinet specially constructed on the starboard side of the charthouse. The method of operation was this. Speed being reduced to a minimum, the "fish" was filled with water by inserting the nozzle of a hose into a filling hole made for the purpose, and, when full, the cap was screwed on the filling hole, and the "fish', which was contained in a cage so constructed as to float in and out of it with very little manipulation, was lowered over the side. The objective of this cage was to prevent the delicate microphones from being thrown out of adjustment by the "fish" getting knocked against the hull of the ship whist lowering or hoisting. Before putting the fish (the "Tadpole" weight) actually in the water, the engines were stopped. but way allowed to remain on the ship The "fish" then floated astern. About twenty yards from the nose of the "fish" a fifty lb. weight, known - on account of its shape - as the "tadpole", was secured to the cable. The object of this weight was to keep the fish submerged and thus ensure the