Misplaced Pages

Revision as of 17:11, 6 March 2007

Hero (or Heron) of Alexandria (Greek: Ήρων ο Αλεξανδρεύς) (c. 10 – 70) was a Greek engineer and geometer in Alexandria, Roman Egypt. 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. This may be due to a misinterpretation of the phrase "first century" or because Hero was a common name.

It is almost certain that Hero taught at the Musaeum which included the famous Library of Alexandria, because most of his writings appear as lecture notes for courses in mathematics, mechanics, physics and pneumatics.

Hero was known for his amazing mechanical ingenuity in the ancient world, to include his contributions in military technology and theater. He also created devices used in temples to instill faith by deceiving believers with "magical acts of the gods."

Projects

• steam turbine (50/62/70) (aeolipile) - the first recorded steam engine, (known as Hero's Engine) which was created almost two millennia before the industrial revolution, which was powered by steam engines. Apparently Hero's steam engine was taken to be no more than a toy, and thus its full potential not realized for centuries.

• The first vending machine was also one of his constructions, when a coin was introducted via a slot on the top of the machine, a set amount of Holy Water was despensed. This was included in his list of inventions in his book, "Mechanics and Optics".

• Hero also invented many mechanisms for the Greek theater, including an entirely mechanical play almost ten minutes in length, powered by a binary-like system of ropes and knots.

• In Optics, Hero formulated the Principle of the Shortest Path of Light: If a ray of light propagates from point A to point B within the same medium, including any number of reflections on plane surfaces, the path-length followed is the shortest possible. Fifteen centuries later, this principle was generalized by Fermat to include the case of refraction at the interface of two different media, and was expressed in the statement that the time taken by the light ray is minimal as compared with neighbouring paths.

Bibliography

Works known to be of Hero's hand:

• Pneumatica, a description of machines working on air, steam or water pressure, including the hydraulis or water organ.
• Automata, a description of machines which enable wonders in temples by mechanical or pneumatical means (e.g. automatic opening or closing of temple doors, statues that pour wine, etc.). See Automata.
• Mechanica, written for architects, containing means to lift heavy objects.
• Metrica, a description of how to calculate surfaces and volumes of diverse objects.
• On the Dioptra, a collection of methods to measure lengths. In this work the odometer is described, and also an apparatus which resembles a theodolite.
• Belopoeica, a description of war machines.
• Catoptrica, about the progression of light, reflection and the use of mirrors.

Works which have sometimes been attributed to Hero, but are now thought to have most likely been written by someone else:

• Geometria, a collection of equations based on the first chapter of Metrica.
• Stereometrica, examples of three dimensional calculations based on the second chapter of Metrica.
• Mensurae, tools which can be used to conduct measurements based on Stereometrica and Metrica.
• Cheirobalistra, about catapults.
• Definitiones, containing definitions of terms for geometry.

References

1. Sadie, Stanley; Tyrrell, John, eds. (2001). The New Grove Dictionary of Music and Musicians (2nd ed.). London: Macmillan Publishers. ISBN 978-1-56159-239-5. {{cite encyclopedia}}: Missing or empty |title= (help)‎
2. O'Connor, J.J. and E.F. Robertson. "Heron biography". The MacTutor History of Mathematics archive. Retrieved 2006-06-18. {{cite web}}: Cite has empty unknown parameter: |1= (help)

See also

• Heron's formula
• Heronian triangle
• Hero's engine

External links

• Webpage about Hero by The Technology Museum of Thessaloniki
• A translation of Pneumatica with diagrams
• Heron, and a translation of Pneumatica in German
• Heron of Alexandria, Inventions, Biography, Science (M. Lahanas)
• Heron biography, The MacTutor History of Mathematics archive

• 10 births
• 70 deaths
• Ancient Greek inventors
• Hellenistic Egyptians
• Inventors
• Geometers
• Ancient Greek mathematicians