The Bullwinkle Show (1959)

Season 1: Episode 4

The origins of Mr. Peabody and the WABAC machine: Mr. Peabody finds Sherman in the street being beaten up by some bigger boys. At first, he doesn't think that he's the right sort of boy- but when he sees how he is treated in the orphanage, Peabody decides to adopt him. At first, there's a problem when they won't let a dog adopt a boy- but he goes to court, and the judge decides that if a boy can have a dog, then a dog can have a boy! Sherman comes to live with Mr. Peabody, who builds him the Wayback Machine in order to keep him busy. They go back in time to Rome, and then to see Ben Franklin.