Editing Steam engine (section)

===Piston steam engines===

[[File:Jacob Leupold Steam engine 1720.jpg|thumb|right|[[Jacob Leupold]]'s steam engine, 1720]]

The first commercially successful engine that could transmit continuous power to a machine was the [[atmospheric engine]], invented by [[Thomas Newcomen]] around 1712.{{efn|Landes{{sfn|Landes|1969|p=101}} refers to Thurston's definition of an engine and Thurston's calling Newcomen's the "first true engine".}}{{sfn|Brown|2002|pp=60-}} It improved on Savery's steam pump, using a piston as proposed by Papin. Newcomen's engine was relatively inefficient, and mostly used for pumping water. It worked by creating a partial vacuum by condensing steam under a piston within a cylinder. It was employed for draining mine workings at depths originally impractical using traditional means, and for providing reusable water for driving waterwheels at factories sited away from a suitable "head". Water that passed over the wheel was pumped up into a storage reservoir above the wheel.{{sfn|Hunter|1985|p=}}<ref>{{cite document
  | last1=Nuvolari | first1=A
  | last2=Verspagen | first2=Bart
  | last3=Tunzelmann | first3=Nicholas
  | date=2003
  | title=The Diffusion of the Steam Engine in Eighteenth-Century Britain. Applied Evolutionary Economics and the Knowledge-based Economy
  | publisher=Eindhoven Centre for Innovation Studies (ECIS)
  | location=Eindhoven, The Netherlands
  | page=3
}}  (Paper to be presented at 50th Annual North American Meetings of the Regional Science Association International 20–22 November 2003)</ref>
In 1780 James Pickard patented the use of a flywheel and crankshaft to provide rotative motion from an improved Newcomen engine.{{sfn|Nuvolari|Verspagen|Tunzelmann|2003|p=4}}

In 1720, [[Jacob Leupold]] described a two-cylinder high-pressure steam engine.<ref>{{cite book
  |last= Galloway |first= Elajah
  |title= History of the Steam Engine
  |publisher =B. Steill, Paternoster-Row |year=1828 |location=London
  |pages=23–24
}}</ref> The invention was published in his major work "Theatri Machinarum Hydraulicarum".<ref>{{cite book
  |last= Leupold |first= Jacob
  |title= Theatri Machinarum Hydraulicarum
  |publisher= Christoph Zunkel |year=1725 |location=Leipzig
}}</ref> The engine used two heavy pistons to provide motion to a water pump. Each piston was raised by the steam pressure and returned to its original position by gravity. The two pistons shared a common four-way [[rotary valve]] connected directly to a steam boiler.

[[File:Watt steam pumping engine.JPG|thumb|Early [[Watt steam engine|Watt]] pumping engine]]
The next major step occurred when [[James Watt (inventor)|James Watt]] developed (1763–1775) [[Watt steam engine|an improved version]] of Newcomen's engine, with a [[History of the steam engine#Watt's separate condenser|separate condenser]]. [[Boulton and Watt]]'s early engines used half as much coal as [[John Smeaton]]'s improved version of Newcomen's.<ref name=HB>{{Harvnb|Hunter|Bryant|1991}} Duty comparison was based on a carefully conducted trial in 1778.</ref> Newcomen's and Watt's early engines were "atmospheric". They were powered by air pressure pushing a piston into the partial [[vacuum]] generated by [[condensation|condensing]] steam, instead of the [[pressure]] of expanding steam. The engine [[Cylinder (engine)|cylinders]] had to be large because the only usable force acting on them was [[atmospheric pressure]].{{sfn|Hunter|1985|p=}}<ref name="Rosen" />

Watt developed his engine further, modifying it to provide a rotary motion suitable for driving machinery. This enabled factories to be sited away from rivers, and accelerated the pace of the Industrial Revolution.<ref name="Rosen">{{cite book
|title=The Most Powerful Idea in the World: A Story of Steam, Industry and Invention
|last1=Rosen
|first1= William
|year= 2012
|publisher = University of Chicago Press
|isbn= 978-0-226-72634-2 |page=185
}}</ref>{{sfn|Hunter|1985|p=}}<ref name="Thomson 2009" />