So recently as the last days of October, 1923, two American seamen, Henry Breault and Lawrence Brown, were immured for thirty hours in a submarine at the bottom of a bay near the Panama Canal. Breault most heroically dashed into the ship as she was sinking to see if he could assist anybody who happened to be within. He found Brown asleep in the torpedo-room, and they just succeeded in closing the door when the O.5 went down in 40 feet of water. There was not a morsel of food aboard, not a drop of drinking water. First the lights failed, then the batteries exploded and caused a fire which blazed furiously for some time. Meantime, a third man, Charles Butler, caught in the engine-room, took refuge in an air pocket, stripped off his clothes and made for the hatchway. Emulating the plucky fellow who escaped from the British submarine, he thrust open the hatch. So enormous was the pressure that he was blown right out of the water, breaking the surface like a leaping salmon. He was soon picked up, after being at the bottom for eight minutes. In three hours the other two prisoners heard the knocks of a diver and knew that attempts were being made to rescue them. Nine hours later they felt the submarine begin to move upward. For a little time she continued to rise, then their hopes were dashed by a sharp snapping sound and they felt their craft fall with a bump to the bottom again. The ticking of the clock for hour after hour, the dreadful dragging of the hands round the face of it nearly drove them distracted. They could not bear to watch it longer. There they sat, wondering, hoping. Another sixteen hours passed before they felt the submarine again begin to rise, moving so slowly that both men were consumed with anxiety. The maddening clock ticked on as the craft was wound up. Water splashed on the deck, the pent-up air gushed out, footsteps sounded and they knew deliverance was at hand. Breault pushed open the hatch and both men stood blinking blindly in the dazzling sunshine. Their heads reeled. So sick and ill were they owing to the sudden change of pressure that grave danger was only averted by quickly placing them under the same pressure in another submarine, and then slowly reducing the pressure in accordance with the recognized diving practice. Thus they came unscathed through their dreadful trial. The K.5 during battle practice with the British Fleet in 1921 sank in such deep water that no attempt was made to recover her. But the American naval experts, when a similar disaster overtook the submarine F.4 at Honolulu in March, 1915, were so anxious to find out what had happened that they determined to do their utmost to retrieve the sunken craft. Going out for a practice spin, the F.4 quietly submerged and was never seen again. Boats were soon in search of her, and the result of dragging operations led to her discovery on the bottom outside Honolulu harbour in just over 50 fathoms, or 304 feet, of water.