“I wonder what you’d have said if he’d lighted in your corn patch,” said Tom, with a grin.
This reminded Mr. Jesson that he ought to see how his corn had withstood the rainstorm, and he hastened off to do this, while the boys got the car out of its shed. Among other adjustments the boys had made that morning, was one involving a change of the gas envelope for a new type which they had invented. Mr. Jesson, on his return from his corn, which he announced was unharmed, noticed the change, the former gas bag having been of a yellow hue. The one the boys had folded on top of the framework that morning was quite black in color.
“Another invention?” inquired Tom’s father, indicating the bag.
“Well, not exactly an invention,” replied Jack, “more of an adaptation. You know that the difficulty in making sustained flights in a dirigible has always been evaporation or the condensation of the gas. This bag is made of a rubber cloth which is interwoven with steel wires and coated with a peculiar air-tight varnish. It makes a very strong fabric, and almost does away with the danger of the bag bursting under the expansion of radolite gas at high altitudes.
“Another feature of it is a small ‘subdivision’ as it were, of its interior. In other words, there is a small balloon or envelope inside the main one. This smaller bag is filled with ordinary air. Now then, when we reach a great height and want to keep on going higher, we pump this ordinary air out of the smaller ‘balloonet’ and the machine rises. At least that’s what we expect it to do. You can see; that by alternately pumping it full or emptying it, we will have—or hope to have—a craft that will always maintain an even keel without danger.”
“That sounds like a great idea,” said Mr. Jesson, “but you haven’t tested it out yet?”
“No, but we hope to have an opportunity to do so before long,” said Jack; “and now, uncle, if you are ready we’ll start. The roads are heavy, and I guess we won’t be able to make very good time.”
“Well, why not fly over?”
“We may have to,” was the rejoinder, “but I don’t want to use the gas-making tank or generator again till it has had a thorough cleaning.”
Jupe, to his unspeakable disgust, was left behind, and stood waving a good-bye to the party as they skimmed off. The road to Pokeville was a fairly good one, and they were able to make about thirty miles an hour over it.