eight o'clock
The following evening Jacob again called , this time accompanied by William . They brought with them another dress similar to their own . Their visit was an hour later than upon the preceding evening . `` I learned , '' Jacob said , `` that the guard was changed at eight o'clock , and it is upon this that the success of our scheme depends . William will immediately leave , and as he has been seen to enter by the guards without , and by those at the prison gate , he will pass out without questioning . In half an hour a fresh guard will be placed at both these points , and you and I will march out together , armed with permission for two preachers to pass . '' The scheme appeared a hopeful one , and William took his departure after a few minutes , saying to the guards without that he went to fetch a book of reference which he needed to convince the hard-hearted reprobate within .