He had now come to the point on which Bennett had written his
warning. Quickly he opened the bag and took out the oxygen helmet,
which he adjusted carefully over his head. Then he set to work
with redoubled energy.

It was that drill as well as his pounding on the rock which had so
alarmed Elaine and Aunt Tabby the night before and which now had
been the signal for Kennedy's excursion of discovery.

. . . . . . .

Our man, whoever he was, must have heard us approaching down the
tunnel, for he paused in his work and the noise of the drill
ceased.

He looked about a moment, then went over to the prop and examined
it, looking up at the roof of the chamber above him. Evidently he
feared that it was not particularly strong.

From our vantage point around the bend in the passageway we could
see this strange and uncouth figure.

"Who is it, do you think?" I whispered, crouching back against the
wall for fear that he might look even around a corner or through
the earth and discover us.

As I spoke, my hand loosened a piece of rock that jutted out and
before I knew it there was a crash.