Hero of Alexandria
First century A.D.
Greek Inventor and Mathematician
Hero (or Heron) of Alexandria was a prolific writer of mathematical and technical textbooks. His best known works are Pneumatics and Metrica. Credited with the invention of an early form of steam engine, Hero created a number of technical devices, including the odometer, dioptra (surveying tool), and screw press.
Little is known about Hero and his life. In fact, the time during which he lived is subject to debate, with speculation ranging from 150 B.C.to A.D. 250. The most accurate estimate appears to be around A.D. 62. Even less is known about his personal life. Due to the number of books he wrote, and the content of these books, it has been suggested that he was appointed to the Museum or the University of Alexandria, where he probably taught mathematics, physics, pneumonics, and mechanics. Many of Hero's books were likely intended to serve as textbooks for his classes. What kind of person Hero was has also been the subject of debate. While some considered him to be incompetent and uneducated, simply copying the works of different scientists, others believed him a skilled mathematician and creative inventor.
Hero wrote many books, with Pneumatics being the longest and perhaps the most read. It was very popular during medieval times and during the Renaissance. The book outlined various pneumatic devices, and shared descriptions of how they worked. Most were no more than toys used for magic and amusement, and has led some scholars to believe he was not a serious scientist or inventor. Hero indicated that some of the inventions were his and that others were borrowed, but did not clarify which ones were actually his, giving the impression that he was merely collecting the knowledge of others. Most formed this opinion before some of Hero's works, such as Metrica and Mechanics, had been found. Metrica, his most important work on geometry, was lost until 1896 and contained formulas to compute the areas of things like triangles, cones, and pyramids. The area of the triangle is often attributed to Hero, but it is likely he borrowed it from Archimedes (287?-212 B.C.) or the Babylonians. Mechanics deals with machines, mechanical problems of daily life, and the construction of engines. Though these books have been criticized for their preoccupation with child-like toys and disorganization, they were likely used as textbooks. The attention to popular toys was probably employed to explain the principles of physics and pneumatics to students, and the lack of proper organization in his books may result from the fact that they were never completed. Other books by Hero include Dioptra, Automata, Barulkos, Belopoiica, Catoprica, Definitiones, Geometrica, De mensuris, and Stereometrica.
One of Hero's greatest achievements was the invention of the aeolipile, considered by many to be the first steam-powered engine. The plans for this machine are found in Pneumatics. Also described in Pneumatics were siphons, a fountain, a coin-operated machine, a fire engine, and other steam-powered machines. In Dioptra, Hero described the diopter or dioptra, a surveying instrument similar to the theodolite. Hero also displayed a familiarity with astronomy in a chapter of Dioptra, in which he described a method for finding the distance between Rome and Alexandria using a graphical formula based on the position of the stars. Another notable invention of Hero's was the screw press; at the time it was a new and more efficient way to extract juice from grapes and to extract oil from olives.
Hero's contribution to science was varied, though his tireless devotion to the collection of ideas and knowledge was significant in itself. Several of Hero's machines, such as the steam engine, are often cited as his most important contributions. While Hero did not invent the steam engine as we now know it, he did contribute to its eventual creation. The steam engine had a major impact on society, allowing physical, time-consuming labor to be completed by a machine, and freeing people to concentrate on other things, like exploration and discovery. The field of mathematics also benefited from Hero. His books chronicled the mathematical knowledge of his day and allowed others who came later to build on that work.
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