A demonstration of one of the first 19th century attempts to produce an environmentally sound, economic and efficient power source. The heat from a small candle sends the Stirling Engine model into oscillation almost immediately. Easy to construct, this unit very visibly demonstrates the Sterling Engine principle. A test tube acts as the cylinder and four marbles work as a transfer piston. As air is heated on one end of the transfer cylinder, it causes the air to expand and move into the cooler end of the cylinder. Here the air cools and contracts; causing the cylinder to lower and the cycle begins again. Instructions included.