HERO OF ALEXANDRIA

'Hero' (or 'Heron') 'of Alexandria' (Greek: Ήρων ο Αλεξανδρεύς) (c. 10 – 70 AD) was a mathematician and engineer who flourished in Alexandria, Roman Egypt. Most scholars consider him to have been a Greek,Enc. Britannica 2007, "Heron of Alexandria" though some consider him Egyptian.
Among his most famous inventions were the first documented steam-powered device, the ''aeolipile'', and a windwheel, constituting one the earliest instances of wind harnessing. He is said to have been a follower of the Atomists. Some of his ideas were derived from the works of Ctesibius.

Contents

Background

Career

Projects

Bibliography

Media

See also

References

External links

Background

His ethnic background was not recorded in ancient times, but scholars believe him to either have been a Greek,^[1] A History and Philosophy of Fluid Mechanics, Gregory A Tokaty, , , Courier Dover Publications, 1994, Academic American Encyclopedia, Grolier Incorporated, , , Grolier University of Michigan, 1989, ^[2] Illustrated Encyclopedia of the Classical World, Israel Shatzman, Michael Avi-Yonah, , , Harper and Row, 1975, The Picture History of Great Inventors, Gillian Clements, , , frances lincoln ltd, 2005, an Egyptian,George Sarton (1936). "The Unity and Diversity of the Mediterranean World", ''Osiris'' '2', p. 406-463 [429].^[3][4]
or possibly even a Phoenician. The historian of mathematics C. B. Boyer writes that Hero's identification as an Egyptian or a Phoenician was largely due to the strong Babylonian influence on his work and that the current consensus is that Hero was a Greek,^[5] though some still consider it very likely that he could have been Egyptian, or possibly a mix of Greek and Egyptian.Victor J. Katz (1998). ''A History of Mathematics: An Introduction'', "Mathematical Methods in Hellenistic Times". Addison Wesley. ISBN 0321016181.^[6]

Career

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. Although the field was not formalized until the 20th century, it is thought that the work of Hero, his "programmable" automated devices in particular, represents some of the first formal research into cybernetics.^[7]
Hero was known for his amazing mechanical ingenuity in the ancient world, to include his contributions in military technology and theatre. He also created devices used in temples to instill faith by deceiving believers with "magical acts of the gods."

Projects

Hero's wind-powered organ (reconstruction)

★ The ''aeolipile'' (50/62/70) (known as ''Hero's engine'') was a rocket-like reaction engine and the first recorded steam engine. It was created almost two millennia before the industrial revolution. Apparently Hero's steam engine was taken to be little more than a toy, the principles behind it were not well understood, and its full potential not realized for a millenium.

★ The first vending machine was also one of his constructions, when a coin was introduced via a slot on the top of the machine, a set amount of Holy Water was dispensed. This was included in his list of inventions in his book, "Mechanics and Optics". When the coin was deposited, it fell upon a pan attached to a lever. The lever opened up a valve which let some water flow out. The pan continued to tilt with the weight of the coin until it fell off, at which point a counter-weight would snap the lever back up and turn off the valve.

★ A windwheel operating an organ, marking probably the first instance of wind powering a machine in history.^{[8] [9]}

★ 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, knots, and simple machines operated by a rotating cylindrical cogwheel. The sound of thunder was produced by the mechanically-timed dropping of metal balls onto a hidden drum.

★ 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, the path-length followed is the shortest possible. It was nearly 1000 years later that Ibn al-Haytham expanded the principle to both reflection and refraction, and the principle was not stated in its modern form until Pierre de Fermat did so in 1662.

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.^[10]

★ ''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:^[11]

★ ''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.

Media

A 2007 The History Channel television show ''Ancient Discoveries'' includes recreations of most of Hero's devices.

See also

★ Heron's formula

★ Heronian triangle

★ Hero's engine

★ Heron's fountain

References

1. The Hutchinson dictionary of scientific biography, Research Machines plc., , , Helicon Publishing, 2004,
2. Encyclopædia Britannica Online - Heron of Alexandria
3. John H. Lienhard, ''Engines of our Ingenuity'', No. 1038: Hero of Alexandria.
4. T. D. De Marco (1974). "Gas-Turbine Standby-Power Generation for Water-Treatment Plants", ''Journal American Water Works Association'' '66' (2), p. 133-138.
5. A History of Mathematics, , , Boyer, , 1968 [1991],
6. Justin E. Wilson (2006). Heron’s Formula, University of North Carolina at Charlotte.
7. Out of control: the new biology of machines, social systems and the economic world, Kelly, Kevin, , , Addison-Wesley, 1994,
8. A.G. Drachmann, "Heron's Windmill", ''Centaurus'', 7 (1961), pp. 145-151
9. Dietrich Lohrmann, "Von der östlichen zur westlichen Windmühle", ''Archiv für Kulturgeschichte'', Vol. 77, Issue 1 (1995), pp.1-30 (10f.)
10.
11. Heron biography O'Connor, J.J. and E.F. Robertson

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