We are told in Chapter 14 about the attempts of Silas to discipline Eppie as she grows up and gets into the kind of mischief that all children do. When she first wanders off and gets all dirty, he resolved to threaten her with putting her in the coal-hole, thinking that the fear that this would instil would be enough for her to realise that she must not wander off. However, when he has to actually follow through with his threat and put her in there, she enjoys it so much and it takes so much time for him to get her clean again that he realises the limitations of this form of discipline:
This total failure of the coal-hole discipline shook Silas's belief in the efficacy of punishment. "She'd take it all for fun," he observed to Dolly, "if I didn't hurt her, and that I can't do, Mrs. Winthrop. If she makes me a bit o'trouble, I can bear it. And she's got no tricks but what she'll grow out of."
So it is that this first failure of discipline leads Silas to rear Eppie without punishment, creating more work for him and taking him away from his weaving, but also showing his love for her and her importance in his life.