How does the scaffold in The Scarlet Letter bring greater meaning to the message, and does how the symbol further Hawthorne's purpose?

At the beginning of The Scarlet Letter, Hester Prynne and her illegitimate child, Pearl, stand on the scaffold in Boston so they can be public objects of scorn. Hawthorne writes, "The very ideal of ignominy was embodied and made manifest in this contrivance of wood and iron" (33). In other words, the scaffold is meant to shame people because it holds the gaze of the person on the scaffold forward so the offender's eyes must meet the crowd's. The scaffold enhances the idea that Hester and her child are outcasts, as they are held aloft from everyone else as sinners. 

At the end of the book, as the Reverend Dimmesdale is dying, he asks Hester and Pearl to help him ascend the scaffold, which he once feared. Hawthorne writes that as Dimmesdale ascends the scaffold, the crowd would not have thought it strange "had he ascended before their eyes . . . fading at last into the light of heaven" (140). Dimmesdale sacrifices himself on his death bed by telling the truth—that he is Pearl's father and a sinner—and the scaffold at this point acquires a symbolism that is similar to the cross on which Jesus Christ was crucified. Hawthorne's message is that Hester, Pearl, and Dimmesdale are saintly, while the crowd that crucified them is evil. The striking symbol of the cross reinforces Hawthorne's message that in Puritan society, those who are outcasts are truly saints while those who cast them out are sinners.