“It will be safe enough to light up now, I guess,” announced Captain Andrews, when the anchorage had been accomplished. Jack had told him previously that they would need deck lights to work by when it was possible to use them without danger of detection. When the incandescents on the after deck were switched on the boys at once fell to work on their “Flying Road Racer,” as Jack and Tom had christened the craft. There was much to be done, and they worked quickly. The tank was supplied with crystals and water, and the gauge before long showed a pressure which the lads knew was sufficient to inflate the bag when occasion arose. This done. Jack determined to make a test of the engines. First, seeing that the neutral clutch was in working order, he pressed a button which set the self-starting apparatus,—run by electricity from a storage battery of great power and lightness,—into action. With a buzz and a whirr the machinery started, and bit by bit the lad speeded the motor up to its maximum number of revolutions per minute,—namely, two thousand. While the crank shafts whirled round he carefully examined the lubricating appliances. They worked as well as everything else, and fully satisfied with his test, the young inventor shut down the engine, with the announcement that so far as the machinery was concerned everything was in readiness for an immediate flight, or ground cruise. While this had been going on, Jupe had been placing a stock of provisions on board, and Captain Andrews had assembled his navigating instruments and chronometers, which he had brought with him from the _Sea King_. By midnight Jack declared that it was time for the aero-auto’s passengers to get aboard. A thrill of excitement ran through the whole party at these words; but Tom seemed suddenly to recollect something and stepped to Jack’s side, talking in a low voice. The young leader nodded his assent to Tom’s proposal, whatever it was, and Tom vanished below, summoning Jupe to help him. When he returned, he had his arms full of mechanical apparatus, and the same was true of Jupe, who grunted under his burdens. All this impedimenta was placed in the tonneau, in lockers under the seats. It now only remained to bolt on the aerial propeller, adjust the side-planes and fix the rudder. This was speedily done. At twelve-thirty o’clock the party cast off the lashings which had bound the Flying Road Racer to the _Vagrant’s_ deck. Jack climbed into the driver’s seat, taking his place at the aerial steering wheel. Tom sat beside him. Captain Andrews, Ned Bangs and Jupe, whose eyes were almost popping out of his head, seated themselves in the broad, roomy tonneau. The lights had already been switched off on I board the _Vagrant_ and everything made snug. The silver casket, the gas-guns, the ammunition, and the other accessories from the Professor’s cabin which had not yet been opened, were, of course, on board the Flying Road Racer.