Editing Centrifugal governor (section)

==History==
[[File:Centrifugal governor in Sluis, Netherlands.JPG|thumb|right|A millstone governor at [[Sluis]] in the [[Netherlands]].]]
Centrifugal governors were invented by [[Christiaan Huygens]] and used to regulate the distance and pressure between [[millstone]]s in [[windmill]]s in the 17th century.<ref>{{citation|last=Hills|first=Richard L|title=Power From the Wind|publisher=Cambridge University Press|year=1996}}</ref><ref>{{cite book|url=https://books.google.com/books?id=iwbWCgAAQBAJ&dq=%22Centrifugal+Governor%22+Huygens&pg=PA36|title=Adaptive Control Processes: A Guided Tour|first=Richard E.|last=Bellman|date=8 December 2015|publisher=Princeton University Press|isbn=9781400874668 |accessdate=13 April 2018|via=Google Books}}</ref>

[[File:Boulton and Watt centrifugal governor-MJ.jpg|thumb|left|upright|Boulton & Watt engine of 1788]]
James Watt applied the same technology to steam engines.<ref name="Hannavy2021">{{cite book |last1=Hannavy |first1=John |title=The Governor: Controlling the Power of Steam Machines |date=2021 |publisher=Pen & Sword Transport |location=Barnsley, S. Yorks. |pages=60-78}}</ref> He designed his first governor (or 'centrifugal speed regulator') in 1788, following a suggestion from his business partner [[Matthew Boulton]]. It was a [[conical pendulum]] governor and one of the final series of innovations Watt had employed for steam engines. 

Over subsequent decades a series of improvements and modifications were made by a number of different engineers and manufacturers. Among the inventors who contributed to development of the governor in the 19th century were Charles Porter, Wilson Hartnell, [[Richard Tangye]], Rudolph Proell and Buss.<ref name="Hannavy2021" />

[[File: Ashton Frost engine governor.jpg|thumb|upright|A Porter governor on a [[Corliss steam engine]]. This design, patented by Charles Porter in 1858, used lighter balls and a sliding weight on the spindle; it suited faster engines.]]
[[File:Governor - 17836825593.jpg|thumb|upright|The Pickering Governor (first patented in 1862) has balls mounted on [[leaf springs]]. It was especially suited to smaller high-speed engines and was manufactured in large numbers.]]
As engine speeds increased, the basic Watt-type governor became less reliable as it would tend to over-compensate, [[oscillating]] between opening and closing the steam valve and preventing the engine from running smoothly.<ref name="Hannavy2021" /> This led to many modifications and variations over time, including the addition of a dead weight around the spindle, and the application of springs as part of the design. A number of different firms of engineers patented their own variation on the concept, which they would apply to their own engines, and more modern governors were sometimes retrofitted to engines already in service.