There was a tense moment; Tom's thumb pressed home the electric button, and then came the explosion.
It seemed for a moment as if everyone was lifted from his feet. They had all stood on their tiptoes, and opened their mouths to lessen the shock, but even then it was terrific. The very ground shook—from the roof of their cave small stones and gravel rattled down on their heads. Their ear-drums were numbed from the shock. And the noise that filled the valley seemed like a thousand thunderbolts merged into one.
Tom rushed from the bomb-proof, dropping the electric button. He caught sight of his gun, resting undisturbed on the improvised carriage.
"Hurray!" he cried in delight. "She stood the charge all right. And look! look!" he cried, as he pointed the glasses toward the distant hillside. "There goes my projectile as straight as an arrow. There! By Cæsar, Ned! It landed within three feet of the target! Oh, you beauty!" he yelled at his giant cannon. "You did all I hoped yon would! Thirty miles, Ned! Think of that! A two-ton projectile being shot thirty miles!"
"It's great, Tom!" yelled his chum, dapping him on the back, and capering about "It's the longest shot on record."
"It certainly is," declared the foreman of the
