"It looks like a small propeller with a torpedo sticking out from the middle of it," laughed Mr. Giddings.
"So it does, dad," agreed Bob. "Well, that's our wireless dynamo. You will notice that the propeller faces ahead, like the big fellow here. When the airplane is flying, the rush of wind spins the fan at a terrific rate, its axle operates a little dynamo in this torpedo-like case and manufactures electric current. The current then passes into this small apparatus here with a bulb attached, which regulates the voltage and sends it up to the instruments in a uniform flow, no matter at what speed the airplane may be going."
"That's a cheap way of getting current," declared the newspaper man, "and a mighty good one, too." He now changed the subject by asking: "How much do you suppose this machine weighs?"
"I have been in smaller ones which weighed, unloaded, as much as three thousand pounds," admitted John Ross, with a peculiar smile. "Put your hands under the Sky-Bird's nose here and see if you can lift her, Mr. Giddings."
"Don't joke that way, John," expostulated Mr. Giddings. "Why, her engines are right above this portion of her, and I couldn't lift one of them alone."
"Just try it anyhow, dad," persisted Bob, who also wore that queer smile.
More to accommodate them than because he expected to accomplish anything, the publisher half-heartedly braced himself in a crouching position and pushed upward on the airplane's front. To his amazement the whole forward part of the machine rose upward a foot in the air, as if it were made of paper.
"My word!" exclaimed Mr. Giddings, letting the craft back upon its wheels. "Who would have thought such a thing? I had faith in this principle of the hollow wings and helium-gas, boys, but I never thought it could reduce the normal weight of the plane to such a vast extent, It is truly a wonderful idea."
"You might not believe it, but the Sky-Bird weighs less than two hundred pounds as she stands," said Paul. "Just before you came today, Mr. Giddings, Bob and I, one at each end, easily lifted her clear off the floor."
"It's what we aimed for, and we've got it," added John with satisfaction, while Tom Meeks nodded his head and ejaculated, "I'd say so! I'd say so!" his whole broad face abeam. "This feather lightness means great lift, great speed, and great cruising range."