"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.