"Me do!" exclaimed Koku the giant, gently pushing Tom to one side. Then the big man, with one hand, raised the hundred-pound weight as easily as if it were a loaf of bread, and deposited it where Tom wanted it.

"Thanks!" exclaimed our hero, with a laugh. "I didn't make any mistake when I brought you home with me, Koku."

"Huh! I could hab lifted dat weight when I was a young feller!" exclaimed Eradicate, who was, it is needless to say, jealous of the giant.

The powder had been put in the firing chamber. The steel socket had been firmly fixed in the earth, so that if the force of the explosion was in a lateral direction, instead of straight up, no damage would result. The weight, even if it shot from the muzzle of the improvised "cannon," would only go harmlessly up in the air, and then drop back. The firing wires were so long that Tom and his friends could stand some distance away.

"Are you all ready?" cried Tom, as he looked to see that the wiring was clear.

"As ready as we ever shall be," replied Mr. Damon, who, with Ned and the others, had taken refuge behind a low hill.

"Oh, this isn't going to be much of an explosion," laughed Tom. "It won't be any worse than a Fourth of July cannon. Here she goes!"

He pressed the electric button, there was a flash, a dull, muffled report and, for a moment, something black showed at the top of the steel chamber. Then it dropped back inside again.

"Pshaw!" cried Tom, in disappointed tones. "It didn't even blow the weight out of the tube. That powder's no good! It's a failure!"

Followed by the others, the young inventor started toward the small square "cannon." Tom wanted to read the records made by the gases.