Hero of Alexandria

Hero (or Heron) of Alexandria (roughly A.D. 10 to roughly A.D. 70) was a Greek engineer. His most famous invention was the first documented steam engine, the aeolipile. He is said to have been a follower of the Atomists[?]. Some of his ideas were derived from the works of Ctesibius[?].

A number of references mention dates around 150 BC, but these are inconsistent with the dates of his publications and inventions. Perhaps this is due to a misinterpretation of the phrase "first century".

Publications

The complete surviving works are:

• Pneumatica (Greek, c. A.D. 60)
• Automata (Greek)
• Mechanics (Arabic)
• Metrics (Arabic)
• Dioptra (Arabic)

In optics, Hero proposed that light travels along the shortest geometric path. This view is no longer accepted, having been replaced by least-time principle.

In geometry, he wrote down the formula (Heron's formula) for calculating the area of a triangle in terms of its sides.

Projects

• compressed-air fountain
• siphons
• automated puppets
• machine for threading wooden screws
• steam turbine (A.D. 50/62/70) (aeolipile)
• density of air
• water organ or hydraulic organ
• odometer

References

The Technology Museum of Thessaloniki has a good web page on Hero at http://www.tmth.edu.gr/en/aet/5/55.