Stratemeyer, Edward: Leo the Circus Boy. v1. 8 Sep 2014
 

Edward L. Stratemeyer (October 4, 1862 – May 10, 1930) was an American publisher and writer of children's fiction. He was one of the most prolific writers in the world, producing in excess of 1,300 books himself, selling in excess of 500 million copies, and created the well-known fictional-book series for juveniles including The Rover Boys, The Bobbsey Twins, Tom Swift, The Hardy Boys, and Nancy Drew series, among others.

Excerpt
“Go after him with the horsewhip, Daniel. Oh! goodness gracious, look at thet now!”
And the woman, or, rather, Tartar, Mrs. Martha Hawkins, held up her hands in terror as the boy on the apple tree suddenly gave a swing, released his feet, and, with a graceful turn forward, landed on his feet on the ground.