Full scale reproduction of a 1/2 H.P. Otto and Langen atmospheric gas engine circa 1867. Modeled after the engine at Rough and Tumble Museum, Kinzers, PA. Uses hydrogen for fuel, timed flame for ignition and a gear rack connected to piston to transfer power to flywheel. Atmospheric pressure (due to partial vacuum in the cylinder) combined with 40kg piston weight create the power stroke as piston moves downward. Oneway clutch allows piston to freely travel (rocket) upwards during gas expansion, then engage on the way back down. Designed attributed to Nicolas Otto, Eugen Langen, and Franz Reuleaux (clutch), with later improvements by Gottlieb Daimler, and Wilhelm Maybach who eventually went on (with Carl Benz) to form DaimlerBenz in 1890.