eleven o'clock
`` Then the only thing for us to do , '' said John , `` is to keep watch . Sam is going to bring the Black Growler back here to-night and some one of us will have to be on guard all the time . '' `` I have got that all fixed , '' said Fred , taking a slip of paper from his pocket as he spoke ; `` I have divided the night into five watches . We 'll let Sam stay on guard until eleven o'clock . I 'll take the watch from eleven P. M. to twelve-thirty A. M. Grant can come on at twelve-thirty and stay until two , then George will take his place and stay until half-past three . John will be the last one and he can be the guard from half-past three until five o ` clock . There wo n't be any need of any one after that because it will be light by that time . ''