Editing History of physics (section)

====Early thermodynamics====
A precursor of the engine was designed by the German scientist [[Otto von Guericke]] who, in 1650, designed and built the world's first [[vacuum pump]] to create a [[vacuum]] as demonstrated in the [[Magdeburg hemispheres]] experiment. He was driven to make a vacuum to disprove Aristotle's long-held supposition that [[Horror vacui (physics)|'Nature abhors a vacuum']]. Shortly thereafter, Irish physicist and chemist Boyle had learned of Guericke's designs and in 1656, in coordination with English scientist [[Robert Hooke]], built an air pump. Using this pump, Boyle and Hooke noticed the pressure-volume correlation for a gas: ''PV'' = ''k'', where ''P'' is [[pressure]], ''V'' is [[volume]] and ''k'' is a constant: this relationship is known as [[Boyle's law]]. In that time, air was assumed to be a system of motionless particles, and not interpreted as a system of moving molecules. The concept of thermal motion came two centuries later. Therefore, Boyle's publication in 1660 speaks about a mechanical concept: the air spring.<ref>New Experiments physico-mechanicall, Touching the Spring of the Air and its Effects (1660). [http://www.imss.fi.it/vuoto/eboyle.html]</ref> Later, after the invention of the thermometer, the property temperature could be quantified. This tool gave [[Joseph Louis Gay-Lussac]] the opportunity to derive [[Gay-Lussac's law|his law]], which led shortly later to the [[ideal gas law]]. But, already before the establishment of the ideal gas law, an associate of Boyle's named [[Denis Papin]] built in 1679 a bone digester, which is a closed vessel with a tightly fitting lid that confines steam until a high pressure is generated.

Later designs implemented a steam release valve to keep the machine from exploding. By watching the valve rhythmically move up and down, Papin conceived of the idea of a piston and cylinder engine. He did not however follow through with his design. Nevertheless, in 1697, based on Papin's designs, engineer [[Thomas Savery]] built the first engine. Although these early engines were crude and inefficient, they attracted the attention of the leading scientists of the time. Hence, prior to 1698 and the invention of the [[steam engine|Savery Engine]], horses were used to power pulleys, attached to buckets, which lifted water out of flooded salt mines in England. In the years to follow, more variations of steam engines were built, such as the [[Newcomen steam engine|Newcomen Engine]], and later the [[Watt steam engine|Watt Engine]]. In time, these early engines would replace horses. Thus, each engine began to be associated with a certain amount of "horse power" depending upon how many horses it had replaced. The main problem with these first engines was that they were slow and clumsy, converting less than 2% of the input [[fuel]] into useful work. In other words, large quantities of coal (or wood) had to be burned to yield a small fraction of work output; the need for a new science of engine [[dynamics (mechanics)|dynamics]] was born.

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