Hero of Alexandria explained
Hero (or Heron) of Alexandria (Greek: Ήρων ο Αλεξανδρεύς) (c. 10 – 70 AD) was a mathematician and engineer who flourished in Alexandria, Roman Egypt and is said to be the greatest experimenter of antiquity.[1]
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.
Background
Heron's origins were not recorded in ancient times, but a careful analysis of history allows historians to make conjectures about his origins. It was once the general agreement that Hero was an Egyptian or a Phoenician, a view that is still held by some scholars,[2]
but the modern scholarly consensus is that he was a Greek.[1][3]The historian of mathematics C. B. Boyer explains 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.[4]
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.[5]
Hero was known for his amazing mechanical ingenuity in the ancient world, including his contributions in military technology and theatre. He also created devices used in temples to instill faith by deceiving believers with "magical hands of the gods."
Inventions and achievements
- The aeolipile (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. Hero's steam engine was used to open temple doors, and as a toy, but the principles behind it were not well understood, and its full potential was not realized for well over a millennium.
- 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.[6] [7]
- 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 this form until Pierre de Fermat did so in 1662; the most modern form is that the path is at an extremum.
- A standalone fountain that operates under self-contained hydrostatic energy. (Heron's fountain)
Mathematics
Heron described a method of iteratively computing the square root. It is also called the Babylonian method, because the Babylonians also probably knew of it before Heron wrote it down.
Bibliography
The most comprehensive edition of Hero's works was published in 5 volumes in Leipzig by the publishing house Teubner in 1903.
Works known to be written by Hero:
- Pneumatica, a description of machines working on air, steam or water pressure, including the hydraulis or water organ.[8]
- 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 Automaton.
- Mechanica, preserved only in Arabic, 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 and the dioptra is described, an apparatus which resembles the 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:[9]
- 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.
Works which are preserverd only in fragments:
Media
A 2007 The History Channel television show Ancient Discoveries includes recreations of most of Heron's devices.
A 1979 Soviet animated short film focuses on Hero's invention of the aeolipile. http://animator.ru/db/?ver=eng&p=show_film&fid=4676
See also
External links
Notes and References
- Book: The Hutchinson dictionary of scientific biography. Research Machines plc.. Abingdon, Oxon. Helicon Publishing. 2004. 546. Hero of Alexandria (lived c. AD 60) Greek mathematician and engineer, the greatest experimentalist of antiquity.
- [George Sarton]
- Book: A History and Philosophy of Fluid Mechanics. Gregory A Tokaty. Courier Dover Publications. 1994. 0486681033. p.26.
Book: Academic American Encyclopedia. Grolier Incorporated. Grolier University of Michigan. 1989. 0717220249. p.144.
Encyclopædia Britannica Online - Heron of Alexandria
Book: Illustrated Encyclopedia of the Classical World. Israel Shatzman, Michael Avi-Yonah. Harper and Row. 1975. 0060101784. p.234.
Book: The Picture History of Great Inventors. Gillian Clements. frances lincoln ltd. 2005. 0711216053. p.13.
Enc. Britannica 2007, "Heron of Alexandria"
- Book: Boyer. Carl Benjamin Boyer. Carl Benjamin Boyer. A History of Mathematics. 1968 [1991]. Greek Trigonometry and Mensuration. 171-172. At least from the days of Alexander the Great to the close of the classical world, there undoubtedly was much intercommunication between Greece and Mesopotamia, and it seems to be clear that the Babylonian arithmetic and algebraic geometry continued to exert considerable influence in the Hellenistic world. This aspect of mathematics, for example, appears so strongly in Heron of Alexandria (fl. ca. A.D. 100) that Heron once was thought to be Egyptian or Phoenician rather than Greek. Now it is thought that Heron portrays a type of mathematics that had long been present in Greece but does not find a representative among the great figures - except perhaps as betrayed by Ptolemy in the Tetrabiblos..
- Book: Kelly, Kevin. Out of control: the new biology of machines, social systems and the economic world. Addison-Wesley. Boston. 1994. 0-201-48340-8.
- A.G. Drachmann, "Heron's Windmill", Centaurus, 7 (1961), pp. 145-151
- Dietrich Lohrmann, "Von der östlichen zur westlichen Windmühle", Archiv für Kulturgeschichte, Vol. 77, Issue 1 (1995), pp.1-30 (10f.)
- Web site: Heron biography. O'Connor, J.J. and E.F. Robertson. 2006-06-18. The MacTutor History of Mathematics archive.
