nine o'clock
`` Was the locking of his rooms usually included among your duties at night ? '' `` Yes , sir ; his private rooms and the hall on the south side . '' `` Did you have any stated time for doing this ? '' `` At nine o'clock , sir . '' `` You locked the rooms as usual last night ? '' `` Yes , sir ; that is , I locked them all right , but it was later than usual . '' `` How was that ? ''