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Aeolipile
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<h2 id="physics">Physics</h2> <p>The aeolipile usually consists of a spherical or cylindrical vessel with oppositely bent or curved <a href="/facts/Nozzle/9z8wqmEC">nozzles</a> projecting outwards. It is designed to rotate on its axis. When the vessel is pressurised with steam, the gas is expelled out of the nozzles, which generates thrust due to the <a href="/facts/Rocket_engine/XT5gaFAb">rocket</a> principle<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> as a consequence of the 2nd and 3rd of <a href="/facts/Newton%27s_laws_of_motion/XKzGTXK1">Newton's laws of motion</a>. When the nozzles, pointing in different directions, produce forces along different lines of action perpendicular to the axis of the <a href="/facts/Bearing_(mechanical)/Tb8HmHWt">bearings</a>, the thrusts combine to result in a rotational moment (mechanical <a href="/facts/Couple_(mechanics)/RtShoent">couple</a>), or <a href="/facts/Torque/KcrcvNtV">torque</a>, causing the vessel to spin about its axis. Aerodynamic drag and frictional forces in the bearings build up quickly with increasing rotational speed (<a href="/facts/Revolutions_per_minute/fdNmLToF">rpm</a>) and consume the accelerating torque, eventually cancelling it and achieving a <a href="/facts/Steady_state/qgrL4BNs">steady state</a> speed. </p><p>Typically, and as Hero described the device, the water is heated in a simple <a href="/facts/Boiler/uPqTq0I6">boiler</a> which forms part of a stand for the rotating vessel. Where this is the case, the boiler is connected to the rotating chamber by a pair of pipes that also serve as the pivots for the chamber. Alternatively the rotating chamber may itself serve as the boiler, and this arrangement greatly simplifies the pivot/bearing arrangements, as they then do not need to pass steam. This can be seen in the illustration of a classroom model shown here. </p> <h2 id="history">History</h2> <p>Both Hero and Vitruvius draw on the much earlier work by <a href="/facts/Ctesibius/sXnu7qn8">Ctesibius</a> (285–222 BC), also known as Ktēsíbios or Tesibius, who was an inventor and mathematician in <a href="/facts/Alexandria/hdg1twWA">Alexandria</a>, <a href="/facts/Ptolemaic_Kingdom/sAg88Lvs">Ptolemaic Egypt</a>. He wrote the first treatises on the science of compressed air and its uses in pumps. </p> <h3>Vitruvius's description</h3> <p><a href="/facts/Vitruvius/IVnqcSzv">Vitruvius</a> (c. 80 BC – c. 15 BC) mentions aeolipiles by name: </p> <p>Aeolipilae are hollow brazen vessels, which have an opening or mouth of small size, by means of which they can be filled with water. Prior to the water being heated over the fire, but little wind is emitted. As soon, however, as the water begins to boil, a violent wind issues forth.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a></p> <h3>Hero's description</h3> <p>Hero (c. 10–70 AD) takes a more practical approach, in that he gives instructions how to make one: </p> <p>No. 50. The Steam-Engine. PLACE a cauldron over a fire: a ball shall revolve on a pivot. A fire is ignited under a cauldron, A B, (fig. 50), containing water, and covered at the mouth by the lid C D; with this the bent tube E F G communicates, the extremity of the tube being fitted into a hollow ball, H K. Opposite to the extremity G place a pivot, L M, resting on the lid C D; and let the ball contain two bent pipes, communicating with it at the opposite extremities of a diameter, and bent in opposite directions, the bends being at right angles and across the lines F G, L M. As the cauldron gets hot it will be found that the steam, entering the ball through E F G, passes out through the bent tubes towards the lid, and causes the ball to revolve, as in the case of the dancing figures.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a></p> <h2 id="practical-usage">Practical usage</h2> <p>It is not known whether the aeolipile was put to any practical use in ancient times, and if it was seen as a pragmatic device, a whimsical novelty, an object of reverence, or some other thing. A source described it as a mere <a href="/facts/Curiosity/Dwvwu4NV">curiosity</a> for the ancient Greeks, or a "party trick".<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> Hero's drawing shows a standalone device, and was presumably intended as a "temple wonder", like many of the other devices described in <i>Pneumatica</i>.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> </p><p><a href="/facts/Vitruvius/IVnqcSzv">Vitruvius</a>, on the other hand, mentions use of the aeolipile for demonstrating the physical properties of the weather. He describes them as: </p> <p>brazen æolipylæ, which clearly shew that an attentive examination of human inventions often leads to a knowledge of the general laws of nature.<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a></p> <p>After describing the device's construction (see above) he concludes: </p> <p>Thus a simple experiment enables us to ascertain and determine the causes and effects of the great operations of the heavens and the winds.<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a></p> <p>In 1543, <a href="/facts/Blasco_de_Garay/q0CMcxjs">Blasco de Garay</a>, a scientist and a captain in the Spanish navy, allegedly demonstrated before the <a href="/facts/Charles_V,_Holy_Roman_Emperor/QdqkWAeq">Holy Roman Emperor, Charles V</a> and a committee of high officials an invention he claimed could propel large ships in the absence of wind using an apparatus consisted of copper boiler and moving wheels on either side of the ship.<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> This account was preserved by the royal Spanish archives at <a href="/facts/Simancas/p6z8xnzN">Simancas</a>.<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a> It is proposed that de Garay used Hero's aeolipile and combined it with the technology used in Roman boats and late medieval galleys.<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a> Here, de Garay's invention introduced an innovation where the aeolipile had practical usage, which was to generate motion to the paddlewheels, demonstrating the feasibility of steam-driven boats.<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a> This claim was denied by Spanish authorities.<a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a> </p> <h2 id="see-also">See also</h2> Wikimedia Commons has media related to Aeolipile. <ul><li><a href="/facts/Catherine_wheel_(firework)/1H5wCwNy">Catherine wheel (firework)</a></li> <li><a href="/facts/Rocket_engine/XT5gaFAb">Rocket engine</a></li> <li><a href="/facts/Segner_wheel/yr8j6tjB">Segner wheel</a></li> <li><a href="/facts/Steam_engine/f7hN8vzm">Steam engine</a></li> <li><a href="/facts/Steam_locomotive/cXEQwhFk">Steam locomotive</a></li> <li><a href="/facts/Steam_rocket/7QDz5GB6">Steam rocket</a></li> <li><a href="/facts/Tip_jet/YxbGwdG2">Tip jet</a></li></ul> <h2 id="further-reading">Further reading</h2> <ul><li>Maloney, Dan (6 October 2020). <a href="https://hackaday.com/2020/10/06/making-a-modern-version-of-a-steam-engine-from-antiquity/">"Making a Modern Version of a Steam Engine From Antiquity"</a>. <i><a href="/facts/Hackaday/TYDXct6M">Hackaday</a></i>. Retrieved 6 October 2020.</li> <li>Keyser, Paul (1 June 1992). <a href="https://www3.nd.edu/~powers/ame.20231/keyser1990.pdf">"A New Look at Heron's "Steam Engine""</a> (PDF). <i><a href="/facts/University_of_Notre_Dame/oplPM5R2">University of Notre Dame</a></i>. Retrieved 25 March 2023.</li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Hero (1851), "Section 50 – The Steam Engine", The Pneumatics of Hero of Alexandria, translated by Bennet Woodcroft, London: Taylor Walton and Maberly, Bibcode:1851phal.book.....W, archived from the original on 11 February 2012 – via University of Rochester <a href="https://web.archive.org/web/20120211223728/http://www.history.rochester.edu/steam/hero/section50.html" target="_blank">https://web.archive.org/web/20120211223728/http://www.history.rochester.edu/steam/hero/section50.html</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Hero (1899). "Pneumatika, Book II, Chapter XI". Herons von Alexandria Druckwerke und Automatentheater (in Greek and German). Wilhelm Schmidt (translator). Leipzig: B.G. Teubner. pp. 228–232. <a href="/wiki/Hero_of_Alexandria" target="_blank">/wiki/Hero_of_Alexandria</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Kirk, William. "The geographical significance of Vitruvius’ de architectura." Scottish Geographical Magazine 69.1 (1953): 1-10. <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>"This toy [Aeolipile] was not the forerunner of any real steam engine, then or later. Such devices represent technical ingenuity but not technological progress." See A. G. Drachmann, The Classical Civilization, pp. 55–56. <a href="/wiki/A._G._Drachmann" target="_blank">/wiki/A._G._Drachmann</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Aeolipile <a href="http://www.daviddarling.info/encyclopedia/A/aeolipile.html" target="_blank">http://www.daviddarling.info/encyclopedia/A/aeolipile.html</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Vitruvius (17 May 2008). De Architectura, book 1. Ten Books on Architecture. Chapter VI, paragraph 2 (pages 24–25). Retrieved 9 December 2021. <a href="/wiki/Vitruvius" target="_blank">/wiki/Vitruvius</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Hero (1851), "Section 50 – The Steam Engine", The Pneumatics of Hero of Alexandria, translated by Bennet Woodcroft, London: Taylor Walton and Maberly, Bibcode:1851phal.book.....W, archived from the original on 11 February 2012 – via University of Rochester <a href="https://web.archive.org/web/20120211223728/http://www.history.rochester.edu/steam/hero/section50.html" target="_blank">https://web.archive.org/web/20120211223728/http://www.history.rochester.edu/steam/hero/section50.html</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Gruntman, Mike (2004). Blazing the Trail: The Early History of Spacecraft and Rocketry. Reston, VA: American Institute of Aeronautics and Astronautics, Inc. p. 1. ISBN 156347705X. <a href="156347705X" target="_blank">156347705X</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>Hero (1851), "Section 50 – The Steam Engine", The Pneumatics of Hero of Alexandria, translated by Bennet Woodcroft, London: Taylor Walton and Maberly, Bibcode:1851phal.book.....W, archived from the original on 11 February 2012 – via University of Rochester <a href="https://web.archive.org/web/20120211223728/http://www.history.rochester.edu/steam/hero/section50.html" target="_blank">https://web.archive.org/web/20120211223728/http://www.history.rochester.edu/steam/hero/section50.html</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Vitruvius (17 May 2008). De Architectura, book 1. Ten Books on Architecture. Chapter VI, paragraph 2 (pages 24–25). Retrieved 9 December 2021. <a href="/wiki/Vitruvius" target="_blank">/wiki/Vitruvius</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>Vitruvius (17 May 2008). De Architectura, book 1. Ten Books on Architecture. Chapter VI, paragraph 2 (pages 24–25). Retrieved 9 December 2021. <a href="/wiki/Vitruvius" target="_blank">/wiki/Vitruvius</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>Kitsikopoulos, Harry (2015). Innovation and Technological Diffusion: An economic history of early steam engines. Oxon: Routledge. p. 5. ISBN 9781138948112. <a href="9781138948112" target="_blank">9781138948112</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>Stone, Joe (2015). Floating Palaces of the Great Lakes: A History of Passenger Steamships on the Inland Seas. Ann Arbor: University of Michigan Press. p. 9. ISBN 9780472071753. <a href="9780472071753" target="_blank">9780472071753</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>Kitsikopoulos, Harry (2015). Innovation and Technological Diffusion: An economic history of early steam engines. Oxon: Routledge. p. 5. ISBN 9781138948112. <a href="9781138948112" target="_blank">9781138948112</a> <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> <li id="fn:15"><p>Stone, Joe (2015). Floating Palaces of the Great Lakes: A History of Passenger Steamships on the Inland Seas. Ann Arbor: University of Michigan Press. p. 9. ISBN 9780472071753. <a href="9780472071753" target="_blank">9780472071753</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li> <li id="fn:16"><p>Museo Naval, Catálogo guia del Museo Naval de Madrid, IX edición, Madrid, 1945, page 128. <a href="#fnref:16" class="footnote-back-ref">↩</a></p></li> </ol>