Chapter XII. A Powerful Blast

"Look out with that box, Koku! Handle it as though it contained a dozen eggs of the extinct great auk, worth about a thousand dollars apiece.

"Eradicate! Don't you dare stumble while you're carrying that tube. If you do, you'll never do it again!"

"By golly, Massa Tom! I--I's gwine t' walk on mah tiptoes all de way!"

Thus Eradicate answered the young inventor, while the giant, Koku, who was carrying a heavy case, nodded his head to show that he understood the danger of his task.

"So you think you've got the right stuff this time, Tom?" asked Ned Newton.

"I'm allowing myself to hope so, Ned."

"Bless my woodpile!" cried Mr. Damon. "I--I really think I'm getting nervous."

It was one afternoon, about two weeks after Tom had made his first test of the new powder. Now, after much hard work, and following many other tests, some of which were more or less successful, he had reached the point where he believed he was on the threshold of success. He had succeeded in making a new explosive that, in the preliminary tests, in which only a small quantity was used, gave promise of being more powerful than any Tom had ever experimented with--his own or the product of some other inventor.

And his experiments had not always been harmless. Once he came within a narrow margin of blowing up the shop and himself with it, and on another occasion some of the slow-burning powder, failing to explode, had set ablaze a shack in which he was working.

Only for the prompt action of Koku, Tom might have been seriously injured. As it was he lost some valuable patterns and papers.

But he had gone on his way, surmounting failure after failure, until now he was ready for the supreme test. This was to be the explosion of a large quantity of the powder in a specially prepared steel tube of great thickness. It was like a miniature cannon, but, unlike the first small one, where the test had failed, this one would carry a special projectile, that would be aimed at an armor plate set up on a big hill.

Tom's hope was that this big blast would show such pressure in foot-tons, and give such muzzle velocity to the projectile, and at the same time such penetrating power, that he would be justified in taking it as the basis of his explosive, and using it in the big gun he intended to make.

The preliminaries had been completed. The special steel tube had been constructed, and mounted on a heavy carriage in a distant part of the Swift grounds. A section of armor plate, a foot and a half in thickness, had been set up at the proper distance. A new projectile, with a hard, penetrating point, had been made--a sort of miniature of the one Tom hoped to use in his giant cannon.

Now the young inventor and his friends were on their way to the scene of the test, taking the powder and other