"I mean it," continued Peter. "Well, what's to keep the water out?" "This," replied his nephew, indicating a zinc-lined wooden box in which the provisions had been stored. "Knock out the bottom and secure the four sides to the bottom of the boat like a square centre-board case. We'll have to caulk the joints and stiffen the box with cross bearers to take the strain of the engine." "Good idea, that," agreed Uncle Brian. "I shouldn't wonder if we get another one and a half knots out of her. She won't drag her stern down so much." "That'll be something to be thankful for," declared Peter. "That stern of hers is a positive danger. Let's set to work." On taking stock of the tools at their disposal, they found they possessed a hatchet, screw-driver, hammer, mallet, and gimlet. There were also copper nails and a few brass screws. By about eleven (judging by the sun, for their watches had been stopped by water penetrating the cases) the box was in position, being secured by two-inch screws through the bottom of the boat. For caulking they used unlaid rope soaked in oil, and clay thinned down with grease. Strips of wood from one of the bottom-boards screwed together formed strengthening cross-pieces. Altogether they had made a sound job in a comparatively short time. "We'll knock off for a bit," said Uncle Brian, wiping the perspiration from his eyes. "It's too risky to swot in the midday heat. We'll make another start when it's a bit cooler." "Right-o," agreed Peter, throwing down his tools with alacrity. "If----" He broke off suddenly and pointed. Brian Strong looked in the direction indicated by his nephew's outstretched hand. Then he muttered under his breath, for a couple of miles away was the misty outline of a Rioguayan flying-boat. CHAPTER XIV A Change of Locomotion "Take cover!" exclaimed Peter warningly, at the same time making for his automatic and ammunition, which were lying on one of the blankets spread out on the beach. "Too late, I fancy," replied Brian. "They've spotted us for a dead cert. We were fools to leave the boat and all this gear strewn over the sand." Nevertheless, Uncle Brian grasped the rifle and automatic pistol and a haversack containing parts of the secret ray invention. Come what may he was not going to let _that_ fall into the hands of the Rioguayans. "Which way?" he inquired. "Up the cliff," replied Peter. "We may be able to stow ourselves away before they are sufficiently above us. There's not very much cover, worse luck." It was fortunate that Peter Corbold had previously found a way to the top. Profiting by the experience, uncle and nephew quickly gained the summit of the cliff. The flying-boat was now about a mile away, but was shaping a course that would bring her to the west of the island. "Don't believe they've spotted us yet," declared Peter. "But they are bound to see our boat if they start cruising over the island. Look! What's wrong with that?"