Improvement in Hot-Air Engines, S. H. Roper, Specification Forming Part of Letters Patent No. 34,333, February 4, 1862

Massachusetts machinist Sylvester Roper patented improvements to a hot air engine that produced motion by harnessing the expansion and contraction of warming and cooling air. This patent covers one of those improvements. Roper also built at least seven steam-powered carriages and two steam-powered motorcycles years before automobiles -- as we know them -- appeared.