Editing James Watt (section)

===Early experiments with steam===
[[File:James Eckford Lauder - James Watt and the Steam Engine- the Dawn of the Nineteenth Century - Google Art Project.jpg|thumb|left|[[James Eckford Lauder]]: ''James Watt and the Steam Engine: the Dawn of the Nineteenth Century'', 1855]]
[[File:Watts First Condenser.jpg|thumb|[[Watt's separate condenser|Original condenser]] by Watt ([[Science Museum (London)|Science Museum]])]]

In 1759 Watt's friend [[John Robison (physicist)|John Robison]] called his attention to the use of steam as a source of [[Power (physics)|motive power]].<ref name="Muirhead1858">{{cite book|last=Muirhead|first=James Patrick|title=The life of James Watt: with selections from his correspondence|url=https://archive.org/details/lifejameswattwi03muirgoog|access-date=17 August 2011|year=1858|publisher=J. Murray|pages=[https://archive.org/details/lifejameswattwi03muirgoog/page/n99 74]–83}}</ref> The design of the Newcomen engine, in use for almost 50 years for pumping water from mines, had hardly changed from its first implementation. Watt began to experiment with steam, though he had never seen an operating steam engine. He tried constructing a model; it failed to work satisfactorily, but he continued his experiments and began to read everything he could about the subject. He came to realise the importance of [[latent heat]]—the [[thermal energy]] released or absorbed during a constant-temperature process—in understanding the engine, which, unknown to Watt, his friend [[Joseph Black]] had previously discovered years before. Understanding of the steam engine was in a very primitive state, for the science of [[thermodynamics]] would not be formalised for nearly another 100 years.

In 1763, Watt was asked to repair a model Newcomen engine belonging to the university.<ref name="Muirhead1858"/> Even after repair, the engine barely worked. After much experimentation, Watt demonstrated that about three-quarters of the thermal energy of the steam was being consumed in heating the [[Cylinder (engine)|engine cylinder]] on every cycle.<ref name="FrazerPa1859">{{cite book|last=Frazer|first=Persifor|title=Journal of the Franklin Institute|url=https://books.google.com/books?id=o3oqAQAAIAAJ&pg=PA296|access-date=17 August 2011|year=1859|pages=296–297}}</ref> This energy was wasted because, later in the cycle, cold water was injected into the cylinder to [[condense]] the steam to reduce its pressure. Thus, by repeatedly heating and cooling the cylinder, the engine wasted most of its thermal energy rather than converting it into [[mechanical energy]].

Watt's critical insight, arrived at in May 1765 as he crossed [[Glasgow Green]] park,<ref>Dickinson, p. 36.</ref> was to cause the steam to condense in a separate chamber apart from the [[piston]], and to maintain the temperature of the cylinder at the same temperature as the injected steam by surrounding it with a "steam jacket".<ref name="FrazerPa1859"/> Thus, very little energy was absorbed by the cylinder on each cycle, making more available to perform useful work. Watt had a working model later that same year.

[[File:James Watt Cottage ruin, Kinneil House, Bo'ness.JPG|thumb|left|The ruin of Watt's cottage workshop at [[Kinneil House]]<ref>{{cite web|title=OS 25-inch 1892–1949|url=http://maps.nls.uk/geo/explore/#zoom=17&lat=56.0081&lon=-3.6337&layers=168&b=1|website=National Library of Scotland|publisher=Ordnance Survey|access-date=26 October 2017}}</ref>]]
[[File:James Watt steam engine relic at the Carron Works.JPG|thumb|[[Cylinder (engine)|Cylinder]] fragment of Watt's first operational engine at the [[Carron Works]], Falkirk]]

Despite a potentially workable design, there were still substantial difficulties in constructing a full-scale engine. This required more [[Financial capital|capital]], some of which came from Black. More substantial backing came from [[John Roebuck]], the founder of the celebrated [[Carron Iron Works]] near [[Falkirk]], with whom he now formed a partnership. Roebuck lived at [[Kinneil House]] in [[Bo'ness]], during which time Watt worked at perfecting his steam engine in a cottage adjacent to the house.<ref>{{cite book|last1=Salmon|first1=Thomas James|title=Borrowstounness and district, being historical sketches of Kinneil, Carriden, and Bo'ness, c. 1550–1850|date=1913|publisher=William Hodge and Co.|location=Edinburgh|pages=372–376|url=https://archive.org/stream/borrowstounnessd00salmrich#page/270/mode/2up|access-date=9 December 2017}}</ref> The shell of the cottage, and a very large part of one of his projects, still exist to the rear.<ref>"James Watt's Cottage", CANMORE. Royal Commission on the Ancient and Historical Monuments of Scotland. Retrieved 13 May 2010.</ref>

The principal difficulty was in machining the piston and cylinder. [[Iron (material)|Iron]] workers of the day were more like [[blacksmith]]s than modern [[machinist]]s, and were unable to produce the components with sufficient precision. Much capital was spent in pursuing a [[patent]] on Watt's invention. Strapped for resources, Watt was forced to take up employment—first as a [[surveyor (surveying)|surveyor]], then as a [[civil engineer]]—for 8 years.<ref>Hills, vol. I, pp. 180–293.</ref>

{{anchor|James Watt's Fire Engines Patent Act 1775}}
Roebuck went [[Bankruptcy in the United Kingdom|bankrupt]], and [[Matthew Boulton]], who owned the [[Soho Manufactory]] works near [[Birmingham]], acquired his patent rights. An [[Patent extensions|extension]] of the patent to 1800 was successfully obtained in 1775.{{efn|James Watt's Fire Engines Patent Act 1775 ([[15 Geo. 3]]. c. 61). At the time, an [[Act of Parliament]] was required to extend a patent.}}

Through Boulton, Watt finally had access to some of the best iron workers in the world. The difficulty of the manufacture of a large cylinder with a tightly fitting piston was solved by [[John Wilkinson (industrialist)|John Wilkinson]], who had developed precision boring techniques for [[cannon]] making at [[Bersham Ironworks|Bersham]], near [[Wrexham]], [[North Wales]]. Watt and Boulton formed a hugely successful partnership, [[Boulton and Watt]], which lasted for the next 25 years.