en it--a difficult task with the new hasps
to any one who did not understand them.

There was no one by the window, but no doubt about the presence of
another in the stone-floored place, for the footsteps had sounded, and
as Tom stood ready to spring he could detect a low panting noise.

"Now then!" he cried; "you hear what I say--give up at once."

There was no reply, and Tom tried to pierce the darkness, and then made
a sudden rush in the direction where he thought the visitor must be.

He was not right, but his action betrayed where the fellow was, for he
rushed across the place, and sent a thrill through Tom's breast.

And now a desperate game at blind-man's-buff commenced, in which he
moved cautiously here and there, with his clenched fists extended ready
to strike or ward off a blow, which was certain to be aimed at him if he
tried to seize the too active enemy.

And as he moved here and there in the cold dark place, he realised how
easily one trying to escape could avoid a would-be captor by keeping
very still and away from the windows, or by ducking down when passing
them. Twice over he touched an arm, once a head, but their owner
bounded away with a faint ejaculation at each touch, and the hunt went
on round and round the place, till both stopped, listening for the
other's next movements.

There was a long period of painful silence.

"He's close to the door," thought Tom at last, for he fancied that the
breathing came from there; and moving slowly and almost imperceptibly,
he glided nearer, holding himself ready to make a spring at the
slightest sound. In this fashion he had half covered the workshop
toward the door, and was in the act of bounding forward the rest of the
way, when he heard a sound behind him, and the next moment the enemy was
rushing up the steps to reach the laboratory again.

"Better than creeping about here in the dark," thought Tom, as he too
rushed for the steps and began to ascend, to have the door banged in his
face, and by the time he had reached it and got through, his quarry was
at the top of the next flight of steps, and had banged down the
trap-door.

Tom was up directly, though, threw the trap over, and sprang panting
into the observatory, to stand in the darkness here too, listening and
trying to make out where his quarry was lying in wait; and heedless of
danger, he did not stop to take a necessary precaution.

Then there came a loud scraping noise from outside, and