Little is known about Hero, or Heron, of Alexandria except that he wrote at least thirteen books on the study and practical applications of the simple machines wedges-- levers, pulleys, and screws.

Hero is thought have lived around the time of the first century. He was a teacher of mathematics, physics, pneumatics, and mechanics at the University of Alexandria. His published works--Pneumatics, Mechanics, Dioptra, Automata, Catoptrica, and Belopoiika--reveal him to be an inventor, especially an inventor of gadgets and automata.

In his work Pneumatics, Hero demonstrates that air is an actual substance, rather than the lack of substance. His simple experiment showed that water could not enter a container of air until air was removed. He further suggested that air was made up of individual particles separated by space and could be compressed into a smaller area. Amazingly, his ideas of gas compression and vacuums were...