twelve o'clock
He might retrieve his error , and no one would be the wiser . `` I 'll do it , '' he said , at length . He went downstairs , and left the hotel without the knowledge of the clerk . Jumping into the horse-cars , he returned to Boston , and entered the Adams House about half-past twelve o'clock . He claimed his key at the desk , and went upstairs to his room . He had scarcely lit the gas , however , when a knock was heard at the door . Opening it unsuspiciously , he turned pale , as he recognized the clerk , in company with an officer of the law .