What is the purpose of the short scene between herrick and the prisoners in the jail? why is herrick drunk? what does this constriubute to the tone of this scene

There are a few possible explanations for the scene that takes place between Herrick, Goody Good, and Tituba at the beginning of Act IV.  The first possible explanation is that the two women are obviously not witches and must put on an act for the jailer, Herrick.  Another possibilty is that the women are slowly going insane from being in such horrible conditions for such a long period of time.  At this point, Tituba and Goody have been in jail the longest, probably a few months, and might even believe that they might be witches at this point.  Finally, Miller could have included this scene for comic relief.  This is almost a comical scene; however, it follows an act that was full of drama and emotion and precedes a scene that will contain even more drama and emotion.