"Something has happened!" cried Mr. Titus as he ran forward, followed by Tom, Mr. Damon and Koku. Professor Bumper started with them, but on the way he saw a curious bit of rock which he stopped to pick up and examine.  
At the entrance of the tunnel, from which came rushing dirt-stained and powder-blackened men, Mr. Titus was met by a man who seemed to be in authority.
 
"Hello, Job!" he cried. "Glad you're back. We're in trouble!"
 
"What's the matter?" was the question. "This is my brother Walter," he said. "This is Tom Swift and Mr. Damon," thus hurriedly he introduced them. "What happened, Walter?"
 
"Premature blast. Third one this week. Somebody is working against us!"
 
"Never mind that now," cried Job Titus. "We must see to the poor fellows who are hurt." "I guess there aren't many," his brother said. "They were on their way out when the charge went off. Some more of Blakeson & Grinder's work, I'll wager!"
 
They were rushing in to the smoke-filled tunnel now, followed by Tom, Mr. Damon and Koku, who would follow his young master anywhere. Tom saw that the tunnel was lighted with incandescent lamps, suspended here and there from the rocky roof or sides. The electric lights were supplied with current from a dynamo run by a gasoline engine.
 
"Where is it, Serato? Where was the blast?" asked Walter Titus, of a tall Indian, who seemed to be in some authority.
 
"Back at second turn," was the answer, in fairly good English. "I go get beds."
 
"He means stretchers," translated Job. "That's our Peruvian foreman. A good fellow, but easily scared."
 
They ran on into the tunnel, Tom and Mr. Damon noticing that a small narrow-gage railroad was laid on the floor, mules being the motive power to bring out the small dump cars loaded with rock and dirt, excavated from the big hole.
 
"Mind the turn!" called Job Titus, who was ahead of Tom and Mr. Damon. "It's rough here."
 
Tom found it so, for he slipped over some pieces of rock, and would have fallen had not Koku held him up.
 
"Thanks," gasped Tom, as on he ran.
 
A little later he came to a place where a cluster of electric lights gave better illumination, and he could see it was there that the damage had been done.
 
A number of men were lying on the dirt and rock floor of the tunnel, and some of them were bleeding. Others were staggering about as though shocked or stunned.
 
"We must get the injured ones out of here!" cried Walter Titus. "Where are the men with stretchers?"
 
"I sint that Spalapeen Serato for thim!" broke in a voice, rich in Irish brogue. "But he's thot stupid he might think I was after sindin' him fer wather!"
 
"No, Tim. Serato is after the stretchers all right," said Walter. "We passed him on the way."
 
"That's Tim Sullivan, our Irish foreman, though he has only a few of his own kind to boss," explained Job Titus in a whisper.
 
Some of the workmen (all of whom save the few Irish referred to were Peruvian Indians) had now recovered from their shock, or fright, and began to help the Titus brothers, Tom, Mr. Damon and Koku in looking after the injured. Of these there were five, only two of whom were, seemingly, seriously hurt.
 
"Me take them out," said Koku, and placing one gently over his left shoulder, and the other over his right, out of the tunnel he stalked with them, not waiting for the stretchers.
 
And it was well he did so, for one man was in need of an immediate operation, which was performed at the rude hospital the contractors maintained at the tunnel mouth. The other man died as Koku was carrying him out, but the giant had saved one life.
 
Serato, the Indian foreman, with some of his men now came in, and the other injured were carried out on stretchers, being attended to by the two doctors who formed part of the tunnel force. Among a large body of men some were always falling ill or getting hurt, and in that wild country a doctor had to be kept near at hand.
 
When the excitement had died down, and it was found that one death would be the total toll of the accident and that the premature blast had done no damage to the tunnel, the two Titus brothers began to consider matters.
 
Tom, Mr. Damon and the two contractors sat in the main office and talked things over. Koku was eating supper, though the others had finished, but, naturally, it took Koku twice as long as any one else. Professor Bumper was busy transcribing material in his note-book.
 
"Well, I'm glad you've come back, Job," said his brother. "Things have been going at sixes and sevens here since you went to get some new kind of blasting powder. By the way, I hope you got it, for we are practically at a standstill."
 
"Oh, I got it all right—some of Tom Swift's best—specially made for us. And, better still, I've brought Tom back with me."
 
"So I see. Well, I'm glad he's here."
 
"Now what about this accident to-day?" went on Job.
 
"Well, as I said, it's the third this week. All of them seemed to be premature blasts. But I've sent for some of the fuses used. I'm going to get at the bottom of this. Here is Sullivan with them now. Come in............