He could easily have been overcome, had the owner been in the
building, for he had forgotten everything but what his eyes were
staring at. He started slowly around the borer, found a long narrow
door slightly ajar, and stepped inside.

This borer, like Guinness's, had a double shell, and much the same
instruments, though the whole job was simpler and cruder. A small
instrument board contained inclination, temperature, depth and
air-purity indicators, and narrow tubes led to the air rectifiers. But
what kept Holmes' attention were the wires running from the magneto to
the mixing chambers of the disintegrating tubes.

"The fools!" he exclaimed, "--they didn't know how to wire the thing!
Or else," he added after a moment, "didn't get around to doing it." He
noticed that the projectile's interior contained no gyroscope: though,
he thought, none would be needed, for the machine, being long and
narrow, could not change keel while in the ground. Here he was
reminded of something. Stepping outside, he estimated the angle the
borer made with the dirt floor. Twenty degrees. "And pointed
southwest!" he exclaimed aloud. "This borer would come close to
meeting the professor's, four miles under our camp!"

* * * * *

At once he knew what he would do. First he went back to the other
shack and got the pail of water he had noticed, and took this out
where the Mexican lay outstretched. He bathed the man's face and the
still slightly bleeding bullet wound in his shoulder.

Presently the wounded man came to. His eyes opened, and he stared up
into a steel mask of a face, in which two level black eyes bored into
his. He remembered that face--remembered it all too well. He trembled,
cowered away.

"No!" he gasped, as if he had seen a ghost. "No--no!"

"Yes, I'm the man," Holmes told him firmly, menacingly. "The same one
you tried to ambush." He paused a moment, then said: "Do you want to
live?"

It was a simple question, frightening in its simplicity.

"Because if you don't answer my questions, I'm going to let you lie
here," Phil went on coldly. "And that would probably mean your death.
If you do answer, I'll fix you up so you can have a chance."

The Mexican nodded eagerly. "I talk," he said.

"Good," said Phil. "Then tell me who built that machine?"

"Senor Quade. Senor James Quade."

"Quade!" Phil had heard the name before. "Of course!" he said.
"Guinness's old partner!"

"I not know," the