When the other boys returned from their various occupations they found Harry squatted near the unfinished glider, contemplating with critical gaze the solitary rib, which he had fastened in place.
The work, so far, consisted of two rectangular frames, each twenty-four by three feet, and joined at the corners by the right-angle braces, fastened with screws. The fact that these frames were four feet longer than the regulation trial glider would seem to indicate a sneaking intention on Harry’s part to install motive power sometime or other; but if he ever did, it is not a part of this story.
Besides the end pieces, four other cross-bars, or struts, had been fastened between the beams at even intervals, except that in one of the frames the two nearest the center were only two feet apart. This would be the under plane, and the space in the center being left uncovered, the passenger might pass his arms over these center cross-bars, hanging by his armpits. The lateral balance of the glider would thus be controlled by the sideways swinging of his legs, and its coasting inclination—that is, the tilting upward or downward of its air-cutting surfaces—by his sliding backward or forward on these central struts.
Thus, in this simple form of glider, the weight of the operator’s body takes the place of complicated stability planes and rudders, and all that is needed to maintain a level keel is a level head.
“That rib looks lonesome there, Harry,” said Tom Langford.
“Well, it will have to stick it out alone to-night,” Harry answered.
“Looks like a fence that’s fallen down, doesn’t it?” said Howard.
They spent some time screwing on more of the right-angle braces, for though they lacked many of the fittings usually recommended for such work, they had an abundance of these braces. They served very well to hold all corners firmly and rigidly together, although of course absolute rigidity of such open framing could only be secured by a thorough system of taut wire trussing.
“Guess she won’t fly away to-night,” said Tom Langford. “Come on down and clean up for supper. I say, it makes me sad to see that lonely rib there.”
The next day they went into Port Henry with the Swan, and got the bicycle, the silk shelter, and the rest of the ribs. There were forty-one, all told. They were curved to perfection, and the boys were vociferous in their thanks to Marty. On the way back, one of them slipped into the water.