This is the external combustion Stirling engine that powers a marble machine. Made in Germany from machine-tooled aluminum and brass, the two-device apparatus is powered by a regenerative heat engine, put to its first practical use in 1818 by Robert Stirling. An alcohol burner in the engine’s rear heats a cylinder; a quick flip of its brass flywheel sets the engine’s displacement and working pistons into motion. The resulting expansion and contraction of heated and cooled air inside the piston spins a series of wheels, one of which connects to the marble machine via a belt. The machine’s wheels raise 25 steel marbles to the top of one of two corkscrews, down which marbles descend until picked up again. Non-toxic exhaust from a full burner of ethyl alcohol allows 15 minutes of operation. The apparatus, belt, and engine requires a footprint of 13" H x 9 1/2" W x 8 1/4" D. (12 1/2 lbs.)