It occurred to him directly that a stone had been thrown in with another threatening scrawl.
But, casting his eye all round, he saw nothing of the kind about.
Then, for a moment, a graver suspicion crossed his mind: might not some detonating substance of a nature to explode when trodden upon, have been flung in?
Hillsborough excelled in deviltries of this kind.
Henry thought of his mother, and would not treat the matter lightly or unsuspiciously.

He stood still till he had lighted a lucifer match, and examined the floor of his room.

Nothing.
He lighted a candle, and examined all the premises.

Nothing.
But, when he brought his candle to the window, he made a discovery: the window had two vertical iron uprights, about three-quarters of an inch in circumference: and one of these revealed to his quick eye a bright horizontal line.

It had been sawed with a fine saw.
Apparently an attempt had been made to enter his room from outside.
The next question was, had that attempt succeeded.
He tried the bar; it was not quite cut through.
He locked the forge up directly, and went to his handling room.