His remarks were rudely interrupted by a sudden rush of compressed air. Before Scott could throw himself clear of the blow-hole he was drenched to the skin by a torrent of water forced through the circular hole in the rock. Sayers yelled with delight, but his mirth was brought to an abrupt termination by a regular waterspout from another blow-hole close to where he was standing. Slipping on the weed-covered rock, he subsided on his back, and while in this ignominious position he was completely enveloped in the falling spray. At the first sign of the spout Atherton, Simpson, Phillips, and Coventry made a hurried dash for the boats. They were only just in time to prevent them from being dashed broadside on to the beach as three rollers in quick succession hurled themselves up the rocks. "It must have been the swell of a steamer," declared Simpson, after the sea had resumed its placid condition. "Steamer? I saw none within a mile or so of shore," remarked Phillips, "and the last one quite a quarter of an hour ago." "That, no doubt, was the one that caused the three rollers," remarked Mr Buckley, who had overheard the Scouts. "The swell of a large steamer, travelling at a fair speed, will be felt five miles off, and at a considerable time after the ship has passed abreast of that part of the shore on which the waves break. But come along, lads, we've seen the blowing holes at work, and some of you have wet shirts in consequence." Into their boats the Scouts jumped, and once more the coasting trip was resumed. Without further incident the lads landed at the cove, hauled the boats up the slope, and returned to camp for dinner. CHAPTER XVIII HOT ON THE TRAIL THE more Atherton thought about one of the crew of the mysterious yacht the more he became convinced that the fellow was Sir Silas Gwinnear's assailant. After dinner, seizing a favourable opportunity, the lad approached his Scoutmaster on the subject. "You're falling a victim to the powers of suggestion, I'm afraid, Atherton," remarked Mr Buckley. "When you first mentioned the matter to me you said you _thought_ he was the man. Now, after ruminating, you come to the conclusion that he _must_ be the culprit. Such definite conclusions based upon flimsy suppositions are dangerous. Over and over again one reads of cases of persons being wrongly arrested owing to definite yet mistaken zeal on the part of an impressionable constable. Now, for example, what do you suggest would be the best course to adopt? Inform the police?" "Yes, sir; my idea is that he should not be allowed to slip through our fingers, so to speak."