The mathematician, geometer and inventor Hero of Alexandria constructed an amazing range of fascinating machines that appear to have no other purpose than to amuse and entertain the public. His aeolipile ("wind ball") is one of the earliest steam engines and combines steam power with the principle of jet propulsion. A sphere mounted on a boiler fitted with two angled nozzles was filled with water. When the steam escaped through the nozzles it made the sphere rotate:
Other inventions include water clocks, steam-powered machines, coin-operated machines and automatons. The figure below shows his automaton "Hercules and the Dragon", reconstructed by Giovanni Battista Aleoti in 1589. As water pours into the container Hercules hits the dragon's head, which causes the dragon to shoot water into Hercules' face:
Among Hero's other inventions are an automatic theatre that opens its doors and shows different scenes with moving figures and a mechanism that opens the doors of a temple when a fire burns on its altar. Hero also invented and described machines for practical use, such as an odometer chariot that measures distance as it travels and the baroulkos, is a weight-lifter in which a succession of gears makes it possible to lift large weights with small effort by turning a crank handle.
Michael Lahanas (2004) Heron of Alexandria. http://www.mlahanas.de/Greeks/HeronAlexandria.htm (accessed 14 October 2004).
Prince of Songkla University (2004) The aeolipile. PSU Virtual Classroom, power plant engineering, http://classroom.psu.ac.th/users/ssmarn/pplant/P5a.htm (accessed 14 October 2004).