Hero of Alexandria (ca. AD 65-125) was a mathematician. His work in geometry contributed to land surveying concepts in use today. He also used geometry to solve problems of length, area, and volume, as well as in the approximation of square roots. Interested in mechanical devices, he invented an accurate water clock and a catapult. All of that would have been enough to ensure his fame, but Hero was also the first to put the principles of fluid dynamics to work.
Hero invented the aeolipile, believed to be the first steam-powered engine. The aeolipile was a hollow copper ball filled with water. The ball had two L-shaped pipes extending from opposite sides of the ball. The ball was held between two poles attached to the north and south poles of the orb and suspended above a fire. When the water inside the ball reached the boiling point, steam was released through the L-shaped pipes. The ball spun, using steam as a means of propulsion for the very first time.
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