gathered
in the vicinity of the Secret House.

T. B. flashed the light of his indispensable and inseparable little
electric lamp into the dark interior.

"I will go in first and see what happens," he said.

"I think we will both go together," said Ela grimly.

"There is a switch here," said T. B.

He pulled it down and a small lamp glowed, illuminating a tiny lift
cage.

"And here I presume are the necessary controlling buttons," said T. B.,
pointing to a number of white discs; "we will try this one."

He pressed the button and instantly the cage began to fall. It came to
a standstill after a while and the men stepped out.

"Part of the old working," said T. B.; "a very ingenious idea."

He flashed his lamp over the walls to find the electrical connection.
They were here, as they were at the other end, perfectly accessible. An
instant later the long corridor was lighted up.

"By heavens," said T. B. admiringly, "they have even got an underground
tramway; look here!"

At this tiny terminus there were two branches of rails and a car was in
waiting. A few minutes later T. B. Smith had reached the other end of
the mine gallery and was seeking the second elevator.

"Here we are," he said--"everything run by electricity. I thought that
power house of Farrington's had a pretty stiff job, and now I see how
heavy is the load which it has to carry. Step carefully into this," he
continued, "and make a careful note of the way we are going. I think we
must be about a hundred feet below the level of the earth; just gauge it
roughly as we go up. Here we go."

He pressed a button and up went the lift. They passed out of the little
mine chamber, carefully propping back the swing door, and made their
way along the corridor.

"This looks like an apartment," said T. B., as he stopped before a
red-painted steel door in one of the walls. He pressed it gently, but it
did not yield. He made a further examination, but there was no keyhole
visible.

"This is either worked by a hidden spring or it does not work at all,"
he said in a low voice.

"If it is a spring," said Ela, "I will find it."

His sensitive hands went up and down the surface of the door and
presently they stopped.

"There is something which is little larger than a pin hole," he said. He
took from his pocket a general utility knife and slipped out a thin
steel needle. "Pipe cleaners may be very useful," he said, and pressed
the long slender bodkin into the