The Sewer
The sewer represents the gateway to Mrs. Ames' transformation as a person. She descends physically underground, as well as symbolically into the unknown territory of her self-transformation.
The sewer also represents the vast differences between the astronomer and the plumber. The plumber's profession requires him to descend into the earth, while the astronomer's deals with exploring the skies. When the plumber asks if Mr. Ames would go down with him to look into the sewage lines, Mrs. Ames replies: "Mr. Ames would never go down there alive. He likes going up..." Later, she decides that men are "divided into two bodies"; those who go up, "as the dead go" and those who go down "like the corporeal being of the dead."
The Cud
While Mrs. Ames informs the maid that she is going down into the sewer, the plumber is telling Mrs. Ames a story of a cow who lost his cud. He tells her that he replaced it in no time, and Mrs. Ames states that she "knew what he said was true." Just prior to this, the plumber assures Mrs. Ames that there is a "remedy for every ill", which seems to reference the fact that he is saving her from an unhealthy marriage.
The story of the cud is significant in that it is also a symbol of the plumber's desire to fix things. He confronts every problem with confidence, eliciting a sense of trust in Mrs. Ames. She admires this quality in him, something her husband lacks.
