"Get off there, Koku!"

"Stand up!"

"Run!"

"Get out uf the way! That's going up!"

Thus cried Tom and his friends to the big, good-natured, but somewhat stupid, giant who had sat down in the dangerous spot. Koku looked toward the hut, in front of which the young inventor and the others stood, waving their hands to him and shouting.

"Get up! Get up!" cried Tom, frantically. The powder is going off, Koku!"

"Can't you stop it?" asked Job Titus.

"No!" answered Tom. "The electric current has already ignited the charge. Only that it's slow-burning it would have been fired long ago. Get up, Koku!"

But the giant did not seem to understand. He waved his hand in friendly greeting to Tom and the others, who dared not approach closer to warn him, for the explosion would occur any second now.

Then Mr. Damon had an inspiration.

"Call him to come to you, Tom!" shouted the odd man. "He always comes to you in a hurry, you know. Call him!"

Tom acted on the suggestion at once.

"Here, Koku!" he cried. "Come here, I want you! Kelos!"

This last was a word in the giant's own language, meaning "hurry." And Koku knew when Tom used that word that there was need of haste. So, though he had sat down, evidently to take his ease after a long tramp through the woods, Koku sprang up to obey his master's bidding.

And, as he did so, something happened. The first spark from the fuse, ignited by the electric current, had reached the slow-burning powder. There was a crackle of flame, and a dull rumble. Koku sprang up from the big stone as though shot. What he saw and heard must have alarmed him, for he gave a mighty jump and started to run, at the same time shouting:

"Me come, Master!"

"You'd better!" cried the young inventor.

Koku got away only just in time, for when he was half way between the group of his friends and the big rock, the utmost force of the explosion was felt. It was not so very loud, but the power of it made the earth tremble.

The rock seemed to heave itself into the air, and when it settled back it was seen to be broken up into many pieces. Koku looked back over his shoulder and gave another tremendous leap, which carried him out of the way of the flying fragments, some of which rattled on the roof of the log hut.

"There!" cried Tom. "I guess something happened that time! The rock is broken up finer than any like it we tried to shatter before. I think I've got the mixture just right!"

"Bless my handkerchief!" cried Mr. Damon. "Think of what might have happened to Koku if he had been sitting there."

"Well," said Tom, "he might not have been killed, for he would probably have been tossed well out of the way at the first slow explosion, but afterward--well, he might have been pretty well shaken up. He got away just in time."

The giant looked thoughtfully back toward the place of the experimental blast.

"Master, him do that?" he asked.

"I did," Tom replied. "But I didn't think you'd walk out of the woods, just at the wrong time, and sit down on that rock."

"Um," murmured the giant. "Koku--he--he --Oh, by golly!" he yelled. And then, as if realizing what he had escaped, and being incapable of expressing it, the giant with a yell ran into the tunnel and stayed there for some time.

The experiment was pronounced a great success and, now that Tom had discovered the right kind of explosive to rend the very hard rock, he proceeded to have it made in sufficiently large quantities to be used in the tunnel.

"We'll have to hustle," said Job Titus. "We haven't much of our contract time left, and I have reason to believe the Peruvian government will not give any extension. It is to their interest to have us fail, for they will profit by all the work we have done, even if they have to pay our rivals a higher price than we contracted for. It is our firm that will pocket the loss."

"Well, we'll try not to have that happen," said Tom, with a smile.

"If you're going to use bigger charges of this new explosive, Tom, won't more rock be brought down?" asked Walter Titus.

"That's what I hope."

"Then we'll need more laborers to bring it out of the tunnel."

"Yes, we could use more I guess. The faster the blasted rock is removed, the quicker I can put in new charges."

"I'll get more men," decided the contractor. "There won't be any trouble now that the hoodoo of the missing workers is solved. I'll tell Serato to scare up all his dusky brethren he can find, and we'll offer a bonus for good work."

The Indian foreman readily agreed to get more laborers.

"And get some big ones, Serato," urged Job Titus. "Get some fellows like Koku," for the giant did the work of three men in the tunnel, not because he was obliged to, but because his enormous strength must find an outlet in action.

"Um want mans like him?" asked the Indian, nodding toward the giant. He and Koku were not on good terms, for once, when Koku was a hurry, he had picked up the Indian (no mean sized man himself) and had calmly set him to one side. Serato never forgave that.

"Sure, get all the giants you can," Tom said. "But I guess there aren't any in Peru."

Where Serato found his man, no one knew, and the foreman would not tell; but a day or so later he appeared at the tunnel camp with an Indian so large in size that he made the others look like pygmies, and many of them were above the average in height, too.

"Say, he's a whopper all right!" exclaimed Tom. "But he isn't as big or as strong as Koku."

"He comes pretty near it," said Job Titus. "With a dozen like him we'd finish the tunnel on time, thanks to your explosive."

Lamos, the Indian giant, was not quite as large as Koku. That is, he was not as tall, but he was broader of shoulder. And as to the strength of the two, well, it was destined to be tried out in a startling fashion.

In about a week Tom was ready with his first charges of the new explosive. The extra Indians were on hand, including Lamos, and great hopes of fast progress were held by the contractors.

The charge was fired and a great mass of broken rock brought down inside the tunnel.

"That's tearing it up!" cried Job Titus, when the fumes had blown away, the secret shaft having been opened to facilitate this. "A few more shots like that and we'll be through the strata of hard rock."

The Indians, Koku and Lamos doing their share of the work, were rushed in to clear away the debris, so another charge might be fired as soon as possible. This would be in a day or so. The contract time was getting uncomfortably close.

Blast after blast was set off, and good progress was made. But instead of half a mile of the extra hard rock the contractors found it would be nearer three quarters.

"It's going to be touch and go, whether or not we finish on time," said Mr. Job Titus one afternoon, when a clearance had been made and the men had filed out to give the drillers a chance to make holes for a new blast.

Tom was about to make a remark when Tim Sullivan came running out of the tunnel, his face showing fright and wonder.

"What's up now, I wonder," said Mr. Titus. "More men missing?"

"Quick! Come quick!" cried the Irishman. "Thim two giants is fightin' in there, an' they'll tear th' tunnel apart if we don't stop 'em. It's an awful fight! Awful!"