In School and Out by Oliver Optic

The window of the chamber was not fastened, and when Richard gained admission, he found the door locked as he had left it. The window must therefore have been closed from the outside; but this did not seem probable, and he came to the conclusion that the sash had dropped of itself. This was a very comforting reflection, and it removed many of the doubts and fears which disturbed him.

Congratulating himself upon his escape from manifold perils by land and water, Richard undressed himself and went to bed. But tired as he was, he could not go to sleep for some time. His brain was busy calculating the chances of detection, and devising schemes to avert suspicion if any should be fastened upon him. Nature triumphed at last, and he went to sleep.