"Go ahead! Help me out!" whispered the older lad to his brother. "Can't you snore too?"
Andy did so. The knock was repeated for the third time and a gruff voice followed, saying:
"Come! Come, young gentlemen. I know you are not asleep. You are up to some mischief, I'm sure. I demand to be admitted at once!"
"Who's there?" asked Frank, simulating a sleepy yawn. "Is any one knocking?"
"Is anyone knocking? I should say there was!" came the rasping voice of Professor Callum. "Let me in instantly. Such conduct is disgraceful. Let me in."
"Come in," called Andy, also yawning. "The door is not locked. But who is it?"
"It is I—Professor Callum," was the reply as the door opened. There was a gasp of surprise from the crabbed instructor as he encountered intense darkness. He had expected to catch the boys with the gas lighted.
He struck a match, and saw two apparently innocent faces gazing at him in mild wonder from the beds. The professor's jaw dropped in chagrin.
"Why—er—that is—I heard noises coming from this room," he said severely. "It is against the rules. But you—you are in bed."
"Yes, Professor," spoke Frank calmly. "We retired early as we were weary. Ahem!"