"Come on!" yelled Ned. "We'll see how this experiment came out!" and he started to run from beneath the shelter of the hill.
"Hold on!" shouted Tom, laying a restraining hand on his chum's shoulder.
"Why, what's the matter?" asked Ned in surprise.
"Some of that powder may not have exploded," went on the young inventor. "From the sound made I should say the gun burst, and, if it did, that gelatin is bound to be scattered about. There may be a mass of it burning loose somewhere, and it may go off. It ought not to, if my theory about it being harmless in the open is correct, but the trouble is that it's only a theory. Wait a few seconds."
Anxiously they lingered, the echoes of the blast still in their ears, and a peculiar smell in their nostrils.
"But there's no smoke," said Mr. Damon. "Bless my spyglass! I always thought there was smoke at an explosion."
"This is a sort of smokeless powder," explained Tom. "It throws off a slight vapor when it is ignited, but not much. I guess it's safe to go out now. Come on!"
He dropped the pushbutton connected with the igniting battery, and, followed by the others, raced to the scene of the experiment. A curious sight met their eyes.
A great hole had been torn in the hillside, and another where the improvised gun had stood. The gun itself seemed to have disappeared.
"Why—why—where is it?" asked Ned.