midnight
In spite of his vexation about his wakefulness , a smile passed over Bob 's face , as he listened to those astonishing voices of the night . Suddenly a sound caught his ears , which at once attracted his attention , and turned all his thoughts in another direction . It was the sound of footsteps immediately in front of the house , and apparently at the doorway . How much time had passed he did not know ; but he felt sure that it must be at least midnight . He now perceived that there were some in the house who had not gone to bed . The footsteps were shuffling and irregular , as though some people were trying to walk without making a noise . The sound attracted Bob , and greatly excited him .