Left to himself, with only the rather silent gang of Peruvian Indians as company, Tom Swift looked about him. There was not much active work to be done, only to see that the Indians filled the dump cars evenly full, so none of the broken rock would spill over the side and litter the tramway. Then, too, he had to keep the Indians up to the mark working, for these men were no different from any other, and they were just as inclined to "loaf on the job" when the eye of the "boss" was turned away.
They did not talk much, murmuring among themselves now and then, and little of what they said was intelligible to Tom. But he knew enough of the language to give them orders, the main one of which was:
"Hurry up!"
Now, having seen to it that the gang of which he was in temporary charge was busily engaged, Tom had a chance to look about him. The tunnel was not new to him. Much of his time in the past month had been spent in its black depths, illuminated, more or less, by the string of incandescent lights.
"What I want to find," mused Tom, as he walked to and fro, "is the place where those Indians disappeared. For I'm positive they got away through some hole in this tunnel. They never came out the main entrance."
Tom held to this view in spite of the fact that nearly every one else believed the contrary—that the men had left by the tunnel mouth, near which Tom happened to be alone at the time.
Now, left to himself, with merely nominal duties, and so disguised that none of the workmen would know him for the trim young inventor who oversaw the preparing of the blast charges, Tom Swift walked to and fro, looking for some carefully hidden passage or shaft by means of which the men had got away.
"For it must be well hidden to have escaped observation so long," Tom decided. "And it must be a natural shaft, or hole, for we are boring into native rock, and it isn't likely that these Indians ever tried to make a tunnel here. There must be some natural fissure communicating with the outside of the mountain, in a place where no one would see the men coming out."
But though Tom believed this it was another matter to demonstrate his belief. In the intervals of seeing that the natives properly loaded the dump cars, and removed as much of the debris as possible, Tom looked carefully along the walls and roof of the tunnel thus far excavated.
There were cracks and fissures, it is true, but they were all superficial ones, as Tom ascertained by poking a long pole up into them.