Having made up his mind on that point, he strode along without swerving, contracting some rather saturnine sternness, as a young man is likely to do who has a premature call upon him for self-reliance.
There are no more uses of "saturnine" in the book.
Show samples from other sources
She was backed in a doorway with her gin and lime, being addressed by a saturnine spritely old gentleman with a hard red face and a hard clear voice and a puff of gray hair over each ear.
Donna Tartt -- The Goldfinch
He had a dark complexion and a small, wise, saturnine face with mournful pouches under both eyes.