"Say, youse, yuh look like de stoin of a ferryboat." (Simile)
This is an insult Yank makes at rich people on Madison Avenue, one of several that makes unflattering comparisons between people's looks and other objects—in this case, a ship's “stern.”
"Steel. Dis si de Zoo, huh?" (Metaphor)
Yank had heard the metaphor of the zoo and pondered it a bit before ending up in jail. This line is the first thing he says in Scene Six, wonderingly, as the steel bars make him think of a zoo's cages.
"The effect is of one fiery eye after another being blotted out with a series of accompanying bangs." (Metaphor)
The stage directions compare the closing and opening of the furnaces with the blinking of eyes, making the machinery of the ship seem like a frightening monster.
"He glares into her eyes, turned to stone." (Metaphor)
The stage directions describe Yank in the very moment he turns around and sees Mildred staring at him in the stokehole. We know that he is feeling aggressive based on his glaring, but his turning to stone is somewhat ambivalent; in the same way, Yank isn't able to easily parse his feelings in the scene following, unsure whether it is hate or love.
"Welcome to your city, huh?" (Metaphor)
When Yank enters the zoo, he compares it to the city, reversing the metaphor he made earlier that the city, or the prison, is like a zoo. Both are brutally animalistic and yet imprisoning.
