What the boys had done was this: They had extended the semi-cylindrical formation till they had formed a full cylinder of light but strong metal. Roughly, the Flying Road Racer now resembled a huge, gleaming white cigar on wheels. Along her sides stretched hollow aluminum planes, or wings.
In the air these took the place of the former planes used in ascending or descending. On the water it was hoped that they would act as hydroplanes, buoying up the craft. But for buoyancy they did not depend on these hydroplanes, or pontoons, alone. The body of the Flying Road Racer was, by a singular stroke of inventive ingenuity, made to be in itself a buoyant craft.
When running along the road, or while flying, the top of the cylindrical body could be opened for air and observation. On a calm sea or lake the boys believed also that the craft, with the aid of the hydroplanes, would float, just like a boat. The hydroplanes at the side would, of course, correct a tendency to roll over, which an unsupported cylindrical body would naturally have. But in case of rough water, during which they might, in the course of the long flights they meant to take, be compelled to descend, the waves would be apt to break over the craft and swamp it.
To provide against such an emergency the ingenuity of the boys had been called into full play. It took many sleepless nights and days of anxious thought to solve the problem. But they believed that they had found a solution. The open space on the top of the cylinder was provided with metal doors which could be closed and screwed down, forming a water-tight compartment. Thus, the Flying Road Racer would, in a rough sea, be a water-tight cylinder, practically unsinkable unless the light metal hull was punctured.
The next problem had been a difficult one likewise. The question of how to ventilate an air-tight and water-tight cylinder was a vexing one. It was Jack who hit upon a plan. Like most big ideas it was simple, and was suggested to him by a recollection of the periscope tube on the submarine Peacemaker, which, as told in “The Boy Inventors and the Diving Torpedo Boat,” they had helped to construct. Jack’s solution, then, was this: A collapsible twin tube was made which when extended fully would reach upward, above the air-tight cylinder, to a height of twenty-five feet. At the bottom of this tube, and inside the cylinder, was a chamber containing two tiny fans. One of these fans, driven by storage batteries, sucked in fresh air from the top of the tube; the other drew out the foul fumes and sent them up the other channel of the extension pipe.
The Wondership was driven in the air and on land and water by the same power, the gas from the storage chamber which formed the lower section of the cylinder. But to fit her for her new work extra powerful engines had been installed, and a propeller of different pattern added. The propeller-shaft was connected to the motor through a water-tight stuffing box, as on a motor boat. The rudder lines, too, led through water-tight connections to the steering wheel. The aerial rudder, being of light metal like the propeller, was capable of use both in the air and water. In place of the old driving mechanism, too, the boys had simplified the Flying Road Racer by their new form of propeller. This did away with the cumbrous connections and clutches to the rear axle. The new form of propeller drew the Wondership along the roads almost as swiftly as it pulled her through the air.
As for the boys themselves, as readers of earlier volumes of this series know, they both lived at High Towers, the estate of Jack’s father, near Nestorville. Jack’s father was an inventor of note, and in our first story, “The Boy Inventors’ Wireless Triumph,” it was described how the boys aided him in many stirring adventures in Yucatan and in the discovery of Tom Jesson’s long missing father, an explorer and naturalist. Since that time Mr. Jesson had made his home with his brother-in-law who, like himself, was a widower. The next volume detailed how Jack and Tom helped an inventor in trouble, and how, after many perils and difficulties, a wonderful vanishing gun was at length brought to perfection in spite of the machinations of a gang of rascals. This volume was called “The Boy Inventors’ Vanishing Gun.”
The third volume has already been referred to. It told how the boys had many exciting times under the ocean and on the surface. The Peacemaker was a wonderful craft and proved of material aid to some Americans beleaguered by blood-thirsty negro revolutionists in Cuba. Through the experiences related in this book both the boys increased their mechanical ability and learned self-reliance and manliness in many a hard test of both those sterling qualities. Had this not been so, it is doubtful if they would ever have had the grit to bring to a triumphant conclusion the construction of the Wondership, beset as their way was oftentimes by apparently insurmountable difficulties. But now, as we know, the Wondership lay finished before them. Already they had tested her in flight to ascertain how she bore the added weight. It was this trial, on which she carried side lights, like a ship, that had caused the flurry in the city papers. It had been a complete success, and only the trial by water remained.
Although Mr. Chadwick and Mr. Jesson knew that the boys were engaged on a supreme task, neither had interfered or asked questions. Jack’s father believed in letting his son solve his own problems. He knew that if occasion arose his advice would be called for. But the boys meant to fight out their battle alone. Even the test to take place that evening was to be unwitnessed, or so they hoped. Not till all was an assured success did they intend to invite their parents to inspect their work.