Who is Austin Lord from Ahab's Wife, or, the Star-gazer: A Novel and what is their importance?

Austin Lord is the judge who lives across the street from Ahab's house. He is left in charge of Una's finances when Ahab is away, and the two become good friends. He moves in with Robben at Siasconset, and they take Jim and Justice to Europe with them. They remain Una's neighbor.