before him. It was a question invented by Wrykyn for use in just such a
case as this.

"I do not propose," said Mr. Downing acidly, "to imitate the noise; you
can all hear it perfectly plainly. It is a curious whining noise."

"They are mowing the cricket field, sir," said the invisible Wilson.
"Perhaps that's it."

"It may be one of the desks squeaking, sir," put in Stone. "They do
sometimes."

"Or somebody's shoes, sir," added Robinson.

"Silence! Wilson?"

"Yes, sir?" bellowed the unseen one.

"Don't shout at me from the corridor like that. Come in."

"Yes, sir!"

As he spoke the muffled whining changed suddenly to a series of tenor
shrieks, and the India-rubber form of Sammy bounded into the room like
an excited kangaroo.

Willing hands had by this time deflected the clockwork rat from the wall
to which it had been steering, and pointed it up the alleyway between
the two rows of desks. Mr. Downing, rising from his place, was just in
time to see Sammy with a last leap spring on his prey and begin