He gave the order to dive. Before the periscope had time to disappear a column of spray dashed up within twenty yards, as a shell from the nearest destroyer ricochetted and plunged with disastrous results into an elegant summer resort on the bank of the Golden Horn. Gently feeling her way, lest any large disturbance of the water should betray her position, the submarine made for the Bosphorus; but before she had covered a quarter of a mile she grounded on a bed of slimy mud. Promptly the Lieutenant-Commander ordered the motors to be switched off. Any attempt to forge ahead would only succeed in churning up vast quantities of mud by the propellers. All that could be done for the time being was to lie low. The thud of machinery announced to the crew that the Ottoman destroyers were cruising over their hiding-place, while muffled detonations at frequent intervals told them that the Turks were making use of explosive grapnels in the hope of locating and shattering the hull of the British submarine. "That's a close one!" muttered Dick, as a sharp detonation resulted in nothing worse than making the submarine roll sluggishly on the mud. It was too close to be pleasant, for, although the water was thick with sediment and effectually precluded daylight from filtering through the observation scuttles, the explosion threw a short blinding flash into the interior of the conning-tower. It was a time of acute peril and mental strain. At any moment one of the submerged charges of gun-cotton might be exploded actually in contact with the steel hull, the crew of which were helpless to raise even a finger in self-defence. But the expected did not happen. Apparently satisfied with the result of their operations, the Turkish destroyers and patrol-boats steamed off, and quietude reigned once more on and under the waters of the Golden Horn. Huxtable was too wily a strategist to move prematurely. It was practically impossible to creep out of the tortuous channel while the submarine was completely submerged. The suspicions of the Turks being aroused, it was equally hazardous to show even a momentary glimpse of the periscope during the hours of daylight. He resolved to lie _perdu_ until nightfall, and then to follow the first steamer that was making for the Bosphorus. "Let's hope that a deep-draughted craft won't be coming down," he remarked. "There's less than twenty-four feet between the protection girder and the surface. This is one of the occasions when my device has obvious drawbacks." "It won't hurt us if the steelwork is hit by a vessel's keel, sir," said Devereux. "I don't know so much about that," objected the Lieutenant-Commander. "The sudden wrench might start some of our plates. In any case the ramming craft would stop to investigate." "Unless she fancied that she'd fouled some of the wreckage of the cruiser we sank," said Dick.