what do you two say to this letter?" continued the master of
Colby Hall, and presented the communication to them.

Jack read the letter with Fred looking over his shoulder. Then, of a
sudden, Fred gave a cry of amazement.

"I think I know who wrote that letter!" he exclaimed.

"You do!" returned Colonel Colby and Jack, simultaneously.

"I think so; although, of course, I am not sure." Fred looked at his
cousin. "It would be just like him to do it."

"Who are you talking about, Fred?"

"I'm talking about Slugger Brown."

"Slugger Brown!"

"Do you mean Slogwell Brown?" queried the master of the school.

"Yes, sir."

"And what makes you think Brown wrote that communication?" demanded
Colonel Colby. And now, somewhat to their wonder, the Rovers realized
that the colonel seemed to be unusually interested.

"Because I once saw Brown writing in backhand fashion on the blackboard
in the gymnasium," explained Fred. "He wrote a hand almost identical
with that. I noticed it particularly, because he was amusing himself by
writing one line slanting backward and the next line slanting forward."

"Did he know you were watching him?"

"Oh, no! I didn't stay there long enough for that. He was all alone,
and as I didn't care to speak to him, I passed out without his noticing
it."

"How long ago was this?"

"Only about a week ago."

"Hum!" The colonel mused for a moment, knitting his brows closely as he
did so. "That is worth investigating." He thought for another moment.
"You have nothing more to add to your story?"

"No, sir," answered Fred.

"I think we've told you everything, Colonel Colby," returned Jack. "We
are innocent, and I trust you will do all you can to help us prove it."

"I shall do what is absolutely fair in the matter," answered Colonel
Colby; and then left the two boys once more to themselves.

Andy and Randy had begged for permission to talk things over with their
cousins, and they came in to see Jack and Fred almost immediately after
Colonel Colby left.

"If Slugger Brown wrote that letter, maybe he and Nappy Martell did the
shooting," remarked Randy.

"They would be just mean enough to do it," added his twin. "They'd do
anything to get our crowd into trouble."

"Why can't you two fellows watch Brown and Martell?" questioned Jack.
"You might tell Gif and Spouter and Ned about it, too. Find out where
those two fellows were yesterday afternoon, and find out if they used
any of the shotguns."