Quickly, yet with hardly a swirl to denote her position, the submarine sank to the bed of the Sea of Marmora. Ten minutes later the dull thud of the steamer's paddles announced the fact that she was passing almost over her unsuspected enemy. "We'll have another squint at her," decided the skipper. "It will be fairly safe to do so, since the Turks will be fully occupied with the visit of the vessel." As soon as the periscope showed a foot above the water the Lieutenant-Commander took a lengthy survey. Then he turned to Crosthwaite, who was the only other officer standing by the bowl of the periscope. "What do you make of that?" he asked. Dick looked. The steamer was now berthed at the head of the pier, on which stood a Turkish lieutenant and the file of sun-helmeted soldiers, all with rifles and fixed bayonets. Passing up the gangway were several men dressed in naval uniforms, while at their heels came more Ottoman soldiers. "Our men!" exclaimed Dick. "I think so, too," replied Huxtable, "but I am not absolutely certain. They are prisoners, that is quite evident." The distance was too great to enable either of the two officers to distinguish details, but the captives were not Frenchmen: the absence of the red tuft on their caps told that. They might be Russians, but it was impossible to see whether they wore the blue-and-white jerseys that would in that case take the place of the flannel "pneumonia catchers" worn by the British bluejacket. All the men wore beards, but, as Dick knew by personal experience, that might be owing to being held in captivity for several weeks without facilities for shaving. As soon as the prisoners were ashore a Turkish officer came off the steamer and engaged in conversation with the lieutenant in charge of the little garrison. A document, apparently a list of the prisoners, changed hands, and the two officers parted, the former returning on board, while the lieutenant leisurely followed the men who were escorting the prisoners towards the tower. The steamer showed no signs of casting off. She strongly resembled the old Thames paddle-wheelers of thirty years or more ago; but a couple of Krupp quick-firers were mounted behind light steel shields--one for'ard, the other aft. As she rolled sluggishly in the slight swell it could be seen that the vessel's hull below the water-line was thickly covered with weeds. "A study in contrasts, sir," observed Dick. "Quick-firers and wireless installation on board a ramshackle paddle-wheeler." "M'yes," admitted Huxtable automatically, for his attention was centred upon the progress of the little band of captives. Closely guarded, they were marched into the tower. Only five soldiers went with them; the rest, having piled arms, either strolled back to the pier or else made for a long, low building that served as a barracks.