The cliff pathway being at last completed, the boys cleared the farther ledge of accidental obstructions, and so formed a fairly smooth surface about sixty yards in length by half as many in breadth. While the workmen were erecting a shed at one end of the space, the boys themselves carried over the parts of the aeroplane, and set about putting them together, with the assistance of Fazl the Gurkha. It was a monoplane of a recent type, with a length of thirty feet and a span of forty-three, the area of the main planes being about three hundred and fifty feet. The fabric-covered fuselage was of approximately stream-line form, deep enough forward to accommodate the pilot so that only his head protruded above the cockpit. This was arranged to seat two, the pilot in front, the passenger in his rear. The elevator was of fixed monoplane design, with rotating ailerons. The engine, a four-cylinder machine of 100 h.p., being of the water-cooled variety, a radiator was necessary: this was incorporated with the lower sloping front of the body. Bob had provided himself with a second carburetter, so that paraffin could be used if petrol ran short. The landing chassis was composed of oval section steel tubes, which ran together at two apexes. At each of these, on a universal bearing, was a laminated spring split into two arms at the rear, with a rubber-tyred wheel between them. The forepart of the spring was attached by an elastic rubber shackle to the top of the chassis, and a similar attachment connected the single wheel with the rear-part of the machine. The material employed in the construction of the machine was mainly wood, which was more easily repairable than steel. Its total weight was about 1000 lbs. and its maximum speed seventy miles an hour in still air. It was a great day at the mine when the young airmen essayed their first flight. Mr. Appleton had looked forward to it with a nervousness he did his best to conceal. He had ceased to joke about the matter, and wore a grave and thoughtful look during the week in which the boys made their final preparations. Their enthusiastic discussion of details at meal-times and in the evening set his nerves on edge; but he was too wise to let his nephews see how they were distressing him, and they did not know until long afterwards how nearly he had come to an absolute prohibition from using their machine. Only as they left him, to try their wings, did he venture on a word of caution. "I say, you fellows, you’ll be careful, you know," he said. "Of course, Uncle," said Bob. "I’ve got my certificate, remember." "And Ditta Lal had his calculations!" he muttered. "Well, they gave him a night out," said Lawrence, quite unconscious how his light answer jarred upon his uncle.