Here is more about the history of the jungle gym and mathematician Charles Hinton, who originally conceived of it as a means to teach children to think in three dimensions and prepare their minds to grasp his obsession, the fourth dimension. His son, lawyer Sebastian Hinton, would go on to patent the “climbing structure” (U.S. Patent 1,471,465 [PDF]) in 1920.
Charles Hinton was not only a pioneer in exploring the fourth dimension, he was a practical inventor. In 1897 he designed a baseball pitching machine for the Princeton University team’s batting practice. The machine was powered by gunpowder and was said to have both a wicked fastball and curve.