Chapter XIII. Casting the Cannon

"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.

"Burst to pieces I guess," replied Tom. "I was afraid that charge was a bit too heavy."

"No, here it is!" shouted Mr. Damon, circling off to one side. "It's been torn from the carriage, and partly buried in the ground," and he indicated a third excavation in the earth.

It was as he had said. The terrific blast had sheared the gun from its temporary carriage, thrown it into the air, and it had come down to bury itself in the soft ground. The carriage had torn loose from the concrete base, and was tossed off in another direction.

"Is the gun shattered?" asked Tom, anxious to know how the weapon had fared. It was, in a sense, a sort of small model of the giant cannon he intended to have cast.

"The breech is cracked a little," answered Mr. Damon, who was examining it; "but otherwise it doesn't seem to be much damaged."

"Good cried Tom. "Another steel jacket will remedy that defect. I guess I'm on the right road at last. But now to see what became of that armor plate."

"Dinner plate not here," spoke Koku, who could not understand how there could be two kind of plates in the world. "Dinner plate gone, but big hole here, and he indicated one in the side of the hill.

"I expect that is where the armor plate is," said Tom,