"Caught red-handed!" exclaimed Kennedy with great satisfaction.

He looked at the tools a minute and then at the electric drill,
and finally an idea seemed to strike him. He took up the drill and
advanced toward the safe. Then he turned on the current and
applied the drill.

The drill was of the very latest design and it went quickly
through the steel. But beyond that there was another thin steel
partition. This Kennedy tackled next.

The drill went through and he withdrew it.

Instantly the most penetrating and nauseous odor seemed to pervade
everything.

Kennedy cried out. But his warning was too late. We staggered
back, overcome by the escaping gas and fell to the ground.

. . . . . . .

Long Sin, with his oxygen helmet on again, had returned to the
passageway and was now stealthily creeping back.

He came to the chamber and there discovered us lying on the
ground, overcome. He bent down and, to his great satisfaction, saw
that we were really unconscious.

Quickly he moved over to the safe and pried open the last thin
steel plate.