, and so balanced that they are easy to carry about from place
to place.

Tom knew the ladder by the shape: it was the one David borrowed from the
next neighbour, against whose long cow-house it always hung on two great
pegs, sheltered from the rain by the thick far-projecting thatch.

And now this ladder had been reared up against the mill, and though the
top rounds could only be dimly-seen, there they were resting up against
the rails of the little gallery, close to the shutter which opened into
the roof of the observatory.

"It's Pete," Tom said to himself, as he stood listening, but only to
hear the beating of his own heart. Then he took three or four steps up
very softly, but stopped short, for all at once there was a gleam of
light in the panes of the laboratory window, such as would be produced
by any one striking a wax-match.

Tom stepped down again, stood looking up a few moments watching the
feeble light, which was little more than would have been produced by the
gleaming of the stars, and then an idea occurred to him.

Getting behind the ladder he gave it a push, and it rose upright
directly, and he found that he had no difficulty in managing it.
Working it to and fro he walked its legs close up to the brick wall, and
then placing his hands upon the rounds, lowered it step by step till it
lay flat in the yard.

"No running away this time," muttered Tom; and he crept back to the
entrance, which he opened softly with the key, entered the workshop, and
then closed the door and locked it on the inside, afterwards placing the
keys in his pocket, but took them out again, for he remembered, what he
had forgotten in his excitement, that since the laboratory had been
furnished, it too had been kept locked, so that to get into the chamber
where he had seen the gleam of light, he would have to unfasten the door
at the top of the flight of steps.

For a brief moment the boy felt nervous, then he was himself again.

"Pete will be in a horrible fright," he thought; and, creeping up, he
softly inserted the key, unlocked this door, and withdrew the key
without a sound. Then slowly and silently he pressed down the
thumb-latch, the door yielded with a faint creak, and he passed in, to
stand listening and looking round.

All was still and very dark, save that he could just make out the shape
of the window, and if any one had passed the panes he might have been
visible as a black shadow.

For an instant Tom wondere