In a comparatively short space of time the swimmers were all picked up, several of them being slightly burned, while in some instances their hair and beards had been singed off. "What has happened, Mr. Kenwyn?" demanded Captain Restronguet, as the unlucky boat’s crew boarded the submarine. "One of the barrels contained sodium carbide, sir, and we didn’t know it till the head was knocked off. There was a lot of water in the bottom of the boat----" "And what caused it to take fire; some one was smoking, eh?" "Yes, sir," replied the second officer. "Was it one of my men?" "No, sir." "Very well, I’ll say no more. Had the culprit been one of the ’Aphrodite’s’ crew there would be trouble; but I do not want to exercise any jurisdiction over the men of the ’Iticaba.’ At the same time, Mr. Kenwyn, it was your duty to keep order in the boat, and with an inflammable cargo of oil on board, you ought to have maintained the strictest vigilance." Kenwyn did not reply. The captain’s strictures were necessary, but the second officer was not a man to make lame excuses, even though one of the seamen from the "Iticaba" had quietly lit his pipe while Kenwyn’s back was turned. The carbide had by now burnt itself out, but patches of burning oil were still drifting shorewards. Nevertheless the object of the expedition was in the main successful, for the seas no longer broke heavily, but continued in a sullen roll right into the deeper water within the creek. Ordering half speed ahead, Captain Restronguet stood by the quartermaster and gave directions as to the course. Gathering way the submarine started on her bid for freedom, the remaining boat of the "Iticaba" being towed astern. No one remained in the boats, while at the stern of the "Aphrodite" a man stood ready with a sharp axe to sever the towing hawser should any of the lumbering craft become swamped. Nearer and nearer to the danger zone the "Aphrodite" headed. Suddenly there was a dull thud. She was aground aft. The boats in tow came surging alongside, only to be swept backwards with a tremendous jerk on the hawser as a roller came swinging by. That wave did it. Lifting the "Aphrodite’s" heel clear of the sand it enabled the submarine under the action of her powerful engines to glide into deep water, followed by the half water-logged flotilla of boats. As soon as a safe distance had been placed between her and the inhospitable shore the submarine eased down; the "Iticaba’s" boats were brought alongside and the work of bringing the "Aphrodite’s" spare gear on board again was pushed forward with feverish energy. All the boats save the largest whaler were cast adrift, as if kept in tow they would have made a great difference in the submarine’s speed, and anxious to fall in with the piratical "Vorwartz," Captain Restronguet ordered a course to be shaped for Zanzibar at the utmost capacity of the "Aphrodite’s" motors. CHAPTER XXIV.