Alongside the _Barnacle_ lay R19, one of the most recent type of submarine craft. She was nearly three hundred feet in length, with a maximum beam of twenty-five feet. Over her bulging hull was a steel platform that afforded almost as much deck-space as that of a light cruiser. Amidships was the conning-tower, oval-shaped, with truncated walls. From the top of the conning-tower projected three tubes, each of about six inches in diameter. Of these two were periscopes--one for the use of the Lieutenant-Commander, the other to enable the helmsman to steer the vessel whilst submerged. The third had a double use. While running awash in a heavy sea it afforded means of ventilation; while diving it acted as a sound-conductor whereby the skipper of the submarine could tell with almost absolute certainty whether there were other vessels in the vicinity and in which direction they bore. Surrounding the conning-tower, and extending twenty feet in its wake, was a steel platform facing the "bridge" of the vessel. Here was a binnacle containing a compass specially designed to withstand a tremendous pressure of water. Close at hand was a telegraph indicator communicating with the motor-room. Around the deck were stanchion-rails, so arranged that they could be automatically lowered to lie flush with the deck when the vessel was trimmed for diving, thus offering no resistance to any obstacle that might be met with. Two open hatchways, one for'ard the other aft, completed the visible fittings of the deck. The four 12-pounder guns, capable of being used as anti-aircraft weapons, were "housed" below, water-tight steel slabs fitting over the hermetically-sealed recesses in which the guns lay until required for action. In the wake of the conning-tower, and just clear of the raised platform, was another closed recess--longer than those for the quick-firers. This was to accommodate a "twenty-foot" whaler, which, with a couple of collapsible canvas Berthons, formed the complement of boats belonging to R19. Down below, the accommodation was vastly superior to the earlier types of submarines at the outbreak of war. Transverse water-tight bulkheads divided the hull into five separate compartments, any one of which could be "holed" without completely destroying the buoyancy of the vessel. The foremost compartment contained the twin bow torpedo-tubes with their store of deadly 21-inch torpedoes. The latter, propelled by super-heated compressed air, had an extreme range of five miles, and could be relied upon to run with unerring aim under the influence of gyroscopically-actuated vertical and horizontal rudders. Beneath the torpedo-room was a roomy space for stores as well as the "cable-manger". The second compartment was given over almost entirely to crew-space, providing sleeping and living accommodation for eighty men.