"Bless my spectacle case!" cried Mr. Damon. "This is the greatest ever!"
"It sure is," agreed Ned. "Tom, my boy, I guess you can now make the longest shots on record."
"I can as soon as I get my giant cannon, perhaps," admitted the young inventor. "I think I have solved the problem of the explosive. Now to work on the cannon."
An examination of the gauges, which, being attached to the cannon and plate by electric wires, were not damaged when the blast came, showed that Tom's wildest hopes had been confirmed. He had the most powerful explosive ever made—or at least as far as he had any knowledge, and he had had samples of all the best makes.
Concerning Tom's powder, or explosive, I will only say that he kept the formula of it secret from all save his father. All that he would admit, when the government experts asked him about it. later, was that the base was not nitro-glycerine, but that this entered into it. He agreed, however, in case his gun was accepted by the government, to disclose the secret to the ordnance-officers.
But Tom's work was only half done. It was one thing to have a powerful explosive, but there must be some means of utilizing it safely—some
