Seizing a spanner, Uncle Brian vigorously attacked the six nuts securing the circular plate on the top of the water-tank. The cover removed, he hacked at the ice until he was able to gather a double handful of chips of frozen water. These he placed in a can and held them over the still warm cylinders of one of the motors until the vessel contained about a pint of fluid. "Look sharp!" shouted Peter. "We can't be much more than a thousand feet up." Working feverishly, Brian poured the water into the generator, turned on the needle-valve to its fullest extent, and applied a match to the triple fish-tail burners. With a mild explosion the gas ignited, and the powerful beam flashed out into the night. "Good heavens!" exclaimed Peter, aghast, for the bright white light was playing on a solid substance less than four hundred yards away--the steeply rising face of a formidable mountain peak. Only a few seconds separated the flying-boat from an end-on crash. Putting the vertical rudders hard over, Peter literally jerked the machine round, tilting her to an angle of nearly sixty degrees as he did so. Unprepared, Uncle Brian lost his balance and fell violently against the lee-side of the compartment. Before he could regain his feet, the flying-boat pancaked and crashed. Peter had a brief vision of the nose crumpling up and the under-carriage being forced through the steel floor of the fuselage. Then the long slender body rose until the tail was almost vertical. The pilot, hurled against the instrument-board, lost all interest in the immediately subsequent proceedings. Brian Strong came off fairly lightly. Owing to the circumstance that he was lying inertly upon the floor--for after his first attempt to rise he had philosophically abandoned further effort--he had escaped being flung headlong against the bulkhead. As it was, he found himself lying on the ground with wreckage on either side of him--while within two yards of his feet were the remains of the acetylene head-light, with a flare of vivid white light leaping twenty feet into the air. "Never did think much of those acetylene lamps," he remarked to himself, and tried to puzzle out by what means he found himself where he was. It was indeed fortunate that the fuel supply of the flying-boat--there were about twenty gallons in the lowermost tank--was non-inflammable when released from pressure; had it been ordinary petrol the wreckage would have been a mass of molten metal and the two airmen would have been burnt to ashes. Still muttering incoherently, Uncle Brian sat up and rubbed his head vigorously. "Where am I?" he demanded. He dug his hands into the ground. It was fine sand. He sniffed at it, half expecting to find it salt like the sand of the seashore. Still puzzled, he watched the strongly-burning acetylene until the glare was too much for his eyes. He turned his head, but was unable to discern a single object.