the
explosives we use merely shatter the face of the cutting, and give us
hardly any progress at all.

"It was after several trials, and when my brother found that he was
making scarcely any progress, compared to the energy of his men and the
blasting, that he wrote to me, explaining matters. I at once thought of
you, Tom Swift, and your powerful explosive, for I had read about it.

"Now then, will you sell us some of your powder--explosive or whatever
you call it--Mr. Swift, or tell us where we can get it? We need it
soon, for we are losing valuable time."

Mr. Titus paused to draw on a piece of paper a rough map of Peru, and
the district where the tunnel was being constructed. He showed where
the two railroad lines were, and where the new route would bring them
together, the tunnel eliminating a big grade up which it would have
been impossible to haul trains of any weight.

"What do you say, Mr. Swift?" the contractor concluded. "Will you let
us have some of your powder? Or, better still, will you come to Peru
yourself? That would suit us immensely, for you could be right on the
ground. And you could carry out your plan of going with your friend
here," and Mr. Titus nodded toward Mr. Damon. "That is, if you were
thinking of going."

"Well, I was thinking of it," Tom admitted. "Mr. Damon and I have been
on so many trips together that it seems sort of natural for us to 'team
it.' I have never been to Peru, and I should like to see the country.
There is only one matter though, that bothers me."

"What is it?" asked Mr. Titus quickly. "If it is a question of money
dismiss it from your mind. The Peruvian government is paying a large
sum for this tunnel, and we stand to make considerable, even if we were
the lowest bidders. We can afford to pay you well--that is, we shall be
able to if we can complete the bore on time. That is what is bothering
me now--the unexpected strata of hard rock we have met with, which
seems impossible to blast. But I feel sure we can do it with the
explosive used in your giant cannon."

"That is just the point!" Tom exclaimed. "I am not so sure my explosive
would do."

"Why not?" the tunnel contractor asked. "It's powerful enough; isn't
it?"

"Yes, it is powerful enough, but whether it will have the right effect
on volcanic rock is hard to say. I should like to see a rock sample."

"I can telegraph to have some sent here to you," said Mr. Titus
eagerly. "Meantime, here is a descripti