so that the
wind of the great blast would not bowl them over like ten pins, stood
Tom Swift and his friends. In his hand Tom held the battery box, the
setting of the switch in which would complete the electrical circuit
and set off the hundreds of pounds of explosive buried deep in the hard
rock.

"Are all the men out?" asked the young inventor of Tim Sullivan, who
had charge of this important matter. Tim was in sole charge as foreman
now, having picked up enough of the Indian language to get along
without an interpreter.

"All out, sor," Tim responded. "Yez kin fire whin ready, Mr. Swift."

It was a portentous moment. No wonder Tom Swift hesitated. In a sense
he and his friends, the contractors, had staked their all on a single
throw. If this blast failed it was not likely that another would
succeed, even if there should be time to prepare one.

The time limit had almost expired, and there was still a half mile of
hard rock between the last heading and the farther end of the big
tunnel. If the blast succeeded enough rock might be brought down to
enable the work to go on, by using a night and day shift of men. Then,
too, there was the chance that the hard strata of rock would come to an
end and softer stone, or easily-dug dirt, be encountered.

"Well, we may as well have it over with," said Tom in a low voice.
Every one was very quiet--tensely quiet.

The young inventor looked up to see Professor Bumper observing him.

"Why, Professor!" Tom exclaimed, "I thought you had gone off to the
mountains again, looking for the lost city."

"I am going, Tom, very soon. I thought I would stop and see the effect
of your big blast. This is my last trip. If I do not find the hidden
city of Pelone this time, I am going to give up."

"Give up!" cried Mr. Damon. "Bless my fountain pen!"

"Oh, not altogether," went on the bald-headed scientist. "I mean I
will give up searching in this part of Peru, and go elsewhere. But I
will never completely give up the search, for I am sure the hidden city
exists somewhere under these mountains," and he looked off toward the
snow-covered peaks of the Andes.

Tom looked at the battery box. He drew a long breath, and said:

"Here she goes!"

There was a contraction of his hand as he pressed the switch over, and
then, for perhaps a half second, nothing happened. Just for an instant
Tom feared something had gone wrong that the electric current had
failed, or that the wires had become dis