Toby Tyler or Ten Weeks with a Circus by James Otis (1848 - 1912)

Toby Tyler tells the story of a ten year-old orphan who runs away from a foster home to join the traveling circus only to discover his new employer is a cruel taskmaster. The difference between the romance of the circus from the outside and the reality as seen from the inside is graphically depicted. Toby's friend, Mr. Stubbs the chimpanzee, reinforces the consequences of what happens when one follows one's natural instincts rather than one's intellect and conscience, a central theme of the novel. (Summary from Wikipedia)