Each of the three men was equipped with a knife, hack-saw, crowbar, a small slate and pencil for communication purposes, and an electric lamp. Their bare hands were protected from the numbing cold by a thick coating of tallow. Their helmets having been placed over their heads, and secured by "butterfly nuts" to their rubber-lined metal collars, Fordyce and his assistants entered the diving-chamber, the inner door of which was secured by clamp locks capable of being operated either from within or without. The Sub's next task, after securing the door, was to flood the diving-chamber. This was done by means of a stopcock communicating with the water outside, while the weight of the inrushing fluid was compensated by expelling a similar quantity from one of the auxiliary ballast-tanks, in order not to disturb the trim of the submarine. The diving-compartment filled, Fordyce threw open the door in the submarine's side; then, groping until he found the lowermost of a series of rungs, he made his way to the deck, where he awaited his companions. Thence the three went towards the bows, flashing their lamps in order to discover the nature of the entanglement. Although each light was of 500 candle-power, the rays were effective only for a distance of five or six yards, but they were sufficient to enable Fordyce to see that a huge large-meshed steel net enclosed R19 on both sides, while towards the bows it contracted, thus preventing further progress in that direction. Cautiously the Sub lowered himself upon the bow diving-rudder on the starboard side. Examination showed that no part of the net was holding it; but the one to port was stubbornly enmeshed. By dint of careful tackling by means of crowbars, the three men succeeded in freeing the projecting plate from the net. As far as could be seen, there was now nothing for'ard to prevent the submarine gathering sternway. Obviously the principal difficulty lay in the fact that one of the propellers had fouled. "By Jove, what's that?" mentally enquired the Sub, as the light of his electric lamp fell upon a huge, ill-defined object less than six feet from R19's bows. It was a part of the upper works of a large tramp vessel, lying slightly on one bilge, and almost hidden by a lavish growth of barnacles and seaweed. It was the wreck of a tramp steamer, possibly a German one sent to the bottom by a British submarine during the early stages of the war. Providentially the steel net had done R19 a good turn, for, had it not stopped her progress, the chances were that the submarine would have collided with the wreck, with disastrous results to herself. Clearly there was no escape for R19 in that direction. The only possible way seemed to lie in the ability of the submarine to back out of the toils, and until the propeller was cleared this could not be attempted.