"Well, their back fins, and they're all heading up this way. Why, they must swarm on the outside of the reef. We might go on killing them all day." "We didn't see any hardly before," said Jack. "Seems as if the more we kill, the more they come to the funeral," cried the doctor. "Oh, the reason is plain enough," said the mate; "they scent the blood, which is carried out by the tide, and the more we kill, the more will come." "Signal from the yacht, sir," said Lenny, pointing to a little flag being run up. "All right. Give way, my lads." The boat's head was turned, and they were rowed rapidly back, this ending the sharking. "Strikes me the captain sights the blacks again," said the mate, and in a few minutes they were alongside. CHAPTER TWENTY FOUR. A CIRCUMNAVIGATION. But no canoes were in sight, for Sir John cried directly-- "Come, I thought you had had long enough for one day. Up with you, we are anxious to be off. Captain Bradleigh says we're wasting steam." "Beg pardon, coals," said the captain, smiling; and giving his orders, the cutter was hoisted up, the screw began to revolve slowly, and with an easy motion the yacht glided on past the opening in the reef, and then to follow the course taken by the boats. Two men were placed forward with leads to keep on sounding, but in a short time it was found that the deep water could easily be traced by its darker colour, and the mate ascended to the foremast-head to con the ship, the navigation proving in such perfectly smooth water free from all danger, so that a fair rate of speed was kept up. The trip was glorious, and as the various points and indentations noted on the previous day were passed, they seemed to display fresh beauties, and Jack, full of animation, kept on calling his father's or the doctor's attention to the manifold points of interest. "Oh!" he cried at last, "if people only knew what they would see if they travelled they would never care to stay at home." "Yes," said Sir John dryly, "if they only knew." They reached the beautiful glen at last, where the two springs--hot and cold--sent their waters into the shadowed pool, Jack being now forward with Edward, who, as an excuse for being well to the front in anything fresh which might arise, made a point of keeping close behind his young master with the glass, which he handed to him from time to time. Now it was to sweep the sea beyond the glittering, misty edge of the reef, where a rainbow showed brilliantly from time to time; now to look up through a deep gash at the summit of the great volcano, which curved upward till its crater was lost in a cloud of vapour. Every now and then too a flock of birds had to be watched in some huge tree a little way back from the sands. And still the yacht glided on in perfect safety hour after hour, with the reef nearer or more distant, but always affording an ample space of deep pellucid water full of the wonders of the tropics, and calling for a brief inspection.