A teacher heard a rapping noise repeatedly one day, just after he had commenced his labors, under such circumstances as to lead him to suppose it was designed.  He did not appear to notice it, but remained after school until the scholars had all gone, and then made a thorough examination.  He found, at length, a broken place in the plastering, where a lath was loose, and a string was tied to the end of it, and thence carried along the wall, under the benches, to the seat of a mischievous boy, and fastened to a nail.  By pulling the string he could spring the lath, and then let it snap back to its place.  He left every thing as it was, and the next day, while engaged in a lesson, he heard the noise again.

He rose from his seat.

The scholars all looked up from their books.

“Did you hear that noise?” said he.

“Yes, sir.”

“Do you know what it is?”

“No, sir.”

“Very well; I only wished to call your attention to it.  I may perhaps speak of it again by-and-by.”

He then resumed his exercise as if nothing had happened.  The guilty boy was agitated and confused, and was utterly at a loss to know what to do.  What could the teacher mean?  Had he discovered the trick? and, if so, what was he going to do?

He grew more and more uneasy, and resolved that, at all events, it was best for him to retreat.  Accordingly, at the next recess, as the teacher had anticipated, he went slyly to the lath, cut the string, then returned to his seat, and drew the line in, rolled it up, and put it in his pocket.  The teacher, who was secretly watching him, observed the whole manoeuvre.

At the close of the school, when the books were laid aside, and all was silence, he treated the affair thus: 

“Do you remember the noise to which I called your attention early this afternoon"?”

“Yes, sir.”

“I will explain it to you now.  One of the boys tied a string to a loose lath in the side of the room, and then, having the end of it at his seat, he was pulling it to make a noise to disturb us.”

The scholars all looked astonished, and then began to turn round toward one another to see who the offender could be.  The culprit began to tremble.

“He did it several times yesterday, and would have gone on doing it had I not spoken about it to-day.  Do you think this was wrong or not?”

“Yes, sir;” “Wrong;” “Wrong,” are the replies.

“What harm does it do?”

“It interrupts the school.”

“Yes.  Is there any other harm?”

The boys hesitate.

“It gives me trouble and pain.  Should you not suppose it would?”

“Yes, sir.”

“Have I ever treated any boy or girl in this school unjustly or unkindly?”

“No, sir;” “No, sir.”

“Then why should any boy or girl wish to give me trouble or pain?”

There was a pause.  The guilty individual expected that the next thing would be to call him out for punishment.