James Watt

James Watt FRS FRSE (/wɒt/; 30 January 1736 (19 January 1736 OS) – 25 August 1819)[1] was a Scottish inventor, mechanical engineer, and chemist who improved on Thomas Newcomen's 1712 Newcomen steam engine with his Watt steam engine in 1776, which was fundamental to the changes brought by the Industrial Revolution in both his native Great Britain and the rest of the world.

While working as an instrument maker at the University of Glasgow, Watt became interested in the technology of steam engines. He realised that contemporary engine designs wasted a great deal of energy by repeatedly cooling and reheating the cylinder. Watt introduced a design enhancement, the separate condenser, which avoided this waste of energy and radically improved the power, efficiency, and cost-effectiveness of steam engines. Eventually he adapted his engine to produce rotary motion, greatly broadening its use beyond pumping water.

Watt attempted to commercialise his invention, but experienced great financial difficulties until he entered a partnership with Matthew Boulton in 1775. The new firm of Boulton and Watt was eventually highly successful and Watt became a wealthy man. In his retirement, Watt continued to develop new inventions though none was as significant as his steam engine work.

He developed the concept of horsepower,[2] and the SI unit of power, the watt, was named after him.

James Watt
Watt James von Breda
Portrait of James Watt (1736–1819)
by Carl Frederik von Breda
Born19 January 1736
Greenock, Renfrewshire, Scotland, United Kingdom
Died25 August 1819 (aged 83)[1]
Handsworth, Birmingham, England, United Kingdom
Resting placeSt. Mary's Church, Handsworth
ResidenceGlasgow, Scotland, then Handsworth, England
Known forWatt steam engine
Separate condenser
Parallel motion
Sun and planet gear (with William Murdoch)
Centrifugal governor
Indicator diagram (with John Southern)
Spouse(s)Margaret Miller (m. 1764-1773 her death)
Anne McGrigor (m.1776-1819 his death)
ChildrenMargaret (1767-1796)
James (1769-1848)
Gregory (1777–1804)
Janet (Jessy; 1779–1794)
Scientific career
Fieldsmechanical engineering
InstitutionsUniversity of Glasgow
Boulton and Watt
InfluencesThomas Newcomen
Joseph Black
Adam Smith
John Robison (physicist)
John Roebuck
James Keir
James Watt Signature

Early life and education

James Watt was born on 19 January 1736 in Greenock, Renfrewshire, the eldest of the five surviving children of Agnes Muirhead (1703–1755) and James Watt (1698–1782).[3] His mother came from a distinguished family, was well educated and said to be of forceful character, while his father was a shipwright, ship owner and contractor, and served as the Greenock's chief baillie in 1751.[3][4] Watts parents were Presbyterians and strong Covenanters,[5] however despite a religious upbringing he later became a deist.[6][7] Watt's grandfather, Thomas Watt (1642–1734), was a teacher of mathematics, surveying and navigation[3] and baillie to the Baron of Cartsburn.[8]

Initially Watt was educated at home by his mother, later going on to attend Greenock Grammar School. There he exhibited an aptitude for mathematics, while Latin and Greek failed to interest him.

He is said to have suffered prolonged bouts of ill-health as a child and from frequent headaches all his life.[3][9]

After leaving school Watt worked in the workshops of his father's businesses, demonstrating considerable dexterity and skill in creating engineering models. After his father suffered some unsuccessful business ventures Watt left Greenock to seek employment in Glasgow as a mathemtical instrument maker. [3]


James Watt by John Partridge, after Sir William Beechey (1806)[10][11]

When he was 18 his mother died and his father's health began to fail. Watt travelled to London and was able to obtain a period of training as an instrument maker for a year (1755/56), then returned to Scotland, settling in the major commercial city of Glasgow intent on setting up his own instrument-making business. He was still very young and having not had a full apprenticeship did not have the usual connections via a former master to establish himself as a journeyman instrument maker.

Watt was saved from this impasse by the arrival from Jamaica of astronomical instruments bequeathed by Alexander Macfarlane to the University of Glasgow, instruments that required expert attention.[12] Watt restored them to working order and was remunerated. These instruments were eventually installed in the Macfarlane Observatory. Subsequently three professors offered him the opportunity to set up a small workshop within the university. It was initiated in 1757 and two of the professors, the physicist and chemist Joseph Black as well as the famed Adam Smith, became Watt's friends.[13]

At first he worked on maintaining and repairing scientific instruments used in the university, helping with demonstrations, and expanding the production of quadrants. He made and repaired brass reflecting quadrants, parallel rulers, scales, parts for telescopes, and barometers, among other things.

It is sometimes falsely stated that he struggled to establish himself in Glasgow due to opposition from the Trades House, but this myth has been thoroughly debunked by the historian, Lumsden. The records from this period are lost but it is known that he was able to work and trade completely normally as a skilled metal worker so the Incorporation of Hammermen must have been satisfied that he met their requirements for membership[14]. It is also known that other people in the metal trades were pursued for working without being members of the Incorporation well into the 19th century, so the rules were definitely being enforced when Watt was trading freely throughout the city.

In 1759 he formed a partnership with John Craig, an architect and businessman, to manufacture and sell a line of products including musical instruments and toys. This partnership lasted for the next six years, and employed up to sixteen workers. Craig died in 1765. One employee, Alex Gardner, eventually took over the business, which lasted into the twentieth century.[15]

In 1764, Watt married his cousin Margaret (Peggy) Miller, with whom he had five children, two of whom lived to adulthood: James Jr. (1769–1848) and Margaret (1767–1796). His wife died in childbirth in 1772. In 1777 he was married again, to Ann MacGregor, daughter of a Glasgow dye-maker, with whom he had two children: Gregory (1777–1804), who became a geologist and mineralogist,[16] and Janet (1779–1794). Ann died in 1832. Between 1777 and 1790 he lived in Regent Place, Birmingham.

Watt and the kettle

There is a popular story that Watt was inspired to invent the steam engine by seeing a kettle boiling, the steam forcing the lid to rise and thus showing Watt the power of steam. This story is told in many forms; in some Watt is a young lad, in others he is older, sometimes it's his mother's kettle, sometimes his aunt's. James Watt of course did not actually invent the steam engine, as the story implies, but dramatically improved the efficiency of the existing Newcomen engine by adding a separate condenser. This is difficult to explain to someone not familiar with concepts of heat and thermal efficiency. It appears that the story of Watt and the kettle was created, possibly by Watt's son James Watt Jr., and persists because it is easy for children to understand and remember.[17] In this light it can be seen as akin to the story of Isaac Newton, the falling apple and his discovery of gravity.

Although it is often dismissed as a myth, like most good stories the story of James Watt and the kettle has a basis in fact. In trying to understand the thermodynamics of heat and steam James Watt carried out many laboratory experiments and his diaries record that in conducting these he used a kettle as a boiler to generate steam.[18]

Early experiments with steam

James Eckford Lauder - James Watt and the Steam Engine- the Dawn of the Nineteenth Century - Google Art Project
James Eckford Lauder: James Watt and the Steam Engine: the Dawn of the Nineteenth Century, 1855

In 1759 Watt's friend, John Robison, called his attention to the use of steam as a source of motive power.[19] 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 some 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.[19] 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 engine cylinder on every cycle.[20] 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,[21] 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."[20] 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.

James Watt Cottage ruin, Kinneil House, Bo'ness
The ruin of Watt's cottage workshop at Kinneil House[22]
James Watt steam engine relic at the Carron Works
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 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.[23] The shell of the cottage, and a very large part of one of his projects, still exist to the rear.[24]

The principal difficulty was in machining the piston and cylinder. Iron workers of the day were more like blacksmiths than modern machinists, 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, then as a civil engineer—for eight years.[25]

Roebuck went bankrupt, and Matthew Boulton, who owned the Soho Manufactory works near Birmingham, acquired his patent rights. An extension of the patent to 1800 was successfully obtained in 1775.[26]

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, who had developed precision boring techniques for cannon making at Bersham, near Wrexham, North Wales. Watt and Boulton formed a hugely successful partnership, Boulton and Watt, which lasted for the next twenty-five years.

First engines

SteamEngine Boulton&Watt 1784
Engraving of a 1784 steam engine designed by Boulton and Watt.

In 1776, the first engines were installed and working in commercial enterprises. These first engines were used to power pumps and produced only reciprocating motion to move the pump rods at the bottom of the shaft. The design was commercially successful, and for the next five years Watt was very busy installing more engines, mostly in Cornwall for pumping water out of mines.

These early engines were not manufactured by Boulton and Watt, but were made by others according to drawings made by Watt, who served in the role of consulting engineer. The erection of the engine and its shakedown was supervised by Watt, at first, and then by men in the firm's employ. These were large machines. The first, for example, had a cylinder with a diameter of some 50 inches and an overall height of about 24 feet, and required the construction of a dedicated building to house it. Boulton and Watt charged an annual payment, equal to one third of the value of the coal saved in comparison to a Newcomen engine performing the same work.

The field of application for the invention was greatly widened when Boulton urged Watt to convert the reciprocating motion of the piston to produce rotational power for grinding, weaving and milling. Although a crank seemed the obvious solution to the conversion Watt and Boulton were stymied by a patent for this, whose holder, James Pickard, and associates proposed to cross-license the external condenser. Watt adamantly opposed this and they circumvented the patent by their sun and planet gear in 1781.

Over the next six years, he made a number of other improvements and modifications to the steam engine. A double acting engine, in which the steam acted alternately on the two sides of the piston was one. He described methods for working the steam "expansively" (i.e., using steam at pressures well above atmospheric). A compound engine, which connected two or more engines was described. Two more patents were granted for these in 1781 and 1782. Numerous other improvements that made for easier manufacture and installation were continually implemented. One of these included the use of the steam indicator which produced an informative plot of the pressure in the cylinder against its volume, which he kept as a trade secret. Another important invention, one which Watt was most proud of, was the parallel motion which was essential in double-acting engines as it produced the straight line motion required for the cylinder rod and pump, from the connected rocking beam, whose end moves in a circular arc. This was patented in 1784. A throttle valve to control the power of the engine, and a centrifugal governor, patented in 1788,[27] to keep it from "running away" were very important. These improvements taken together produced an engine which was up to five times as efficient in its use of fuel as the Newcomen engine.

Because of the danger of exploding boilers, which were in a very primitive stage of development, and the ongoing issues with leaks, Watt restricted his use of high pressure steam – all of his engines used steam at near atmospheric pressure.

Patent trials

20070616 Dampfmaschine
A steam engine built to James Watt's patent in 1848 at Freiberg in Germany

Edward Bull started constructing engines for Boulton and Watt in Cornwall in 1781. By 1792 he had started making engines of his own design, but which contained a separate condenser, and so infringed Watt's patents. Two brothers, Jabez Carter Hornblower and Jonathan Hornblower Jnr also started to build engines about the same time. Others began to modify Newcomen engines by adding a condenser, and the mine owners in Cornwall became convinced that Watt's patent could not be enforced. They started to withhold payments due to Boulton and Watt, which by 1795 had fallen. Of the total £21,000 (equivalent to £2,130,000 as of 2018) owed, only £2,500 had been received. Watt was forced to go to court to enforce his claims.[28]

He first sued Bull in 1793. The jury found for Watt, but the question of whether or not the original specification of the patent was valid was left to another trial. In the meantime, injunctions were issued against the infringers, forcing their payments of the royalties to be placed in escrow. The trial on determining the validity of the specifications which was held in the following year was inconclusive, but the injunctions remained in force and the infringers, except for Jonathan Hornblower, all began to settle their cases. Hornblower was soon brought to trial and the verdict of the four judges (in 1799) was decisively in favour of Watt. Their friend John Wilkinson, who had solved the problem of boring an accurate cylinder, was a particularly grievous case. He had erected about twenty engines without Boulton's and Watts' knowledge. They finally agreed to settle the infringement in 1796.[29] Boulton and Watt never collected all that was owed them, but the disputes were all settled directly between the parties or through arbitration. These trials were extremely costly in both money and time, but ultimately were successful for the firm.

Copying machine

Portable Copying Machine by James Watt & Co
Portable Copying Machine by James Watt & Co. Circa 1795

Before 1780 there was no good method for making copies of letters or drawings. The only method sometimes used was a mechanical one using linked multiple pens. Watt at first experimented with improving this method, but soon gave up on this approach because it was so cumbersome. He instead decided to try to physically transfer some ink from the front of the original to the back of another sheet, moistened with a solvent, and pressed to the original. The second sheet had to be thin, so that the ink could be seen through it when the copy was held up to the light, thus reproducing the original exactly.[30][31]

Watt started to develop the process in 1779, and made many experiments to formulate the ink, select the thin paper, to devise a method for wetting the special thin paper, and to make a press suitable for applying the correct pressure to effect the transfer. All of these required much experimentation, but he soon had enough success to patent the process a year later. Watt formed another partnership with Boulton (who provided financing) and James Keir (to manage the business) in a firm called James Watt and Co. The perfection of the invention required much more development work before it could be routinely used by others, but this was carried out over the next few years. Boulton and Watt gave up their shares to their sons in 1794.[32] It became a commercial success and was widely used in offices even into the twentieth century.

Chemical experiments

From an early age Watt was very interested in chemistry. In late 1786, while in Paris, he witnessed an experiment by Berthollet in which he reacted hydrochloric acid with manganese dioxide to produce chlorine. He had already found that an aqueous solution of chlorine could bleach textiles, and had published his findings, which aroused great interest among many potential rivals. When Watt returned to Britain, he began experiments along these lines with hopes of finding a commercially viable process. He discovered that a mixture of salt, manganese dioxide and sulphuric acid could produce chlorine, which Watt believed might be a cheaper method. He passed the chlorine into a weak solution of alkali, and obtained a turbid solution that appeared to have good bleaching properties. He soon communicated these results to James McGrigor, his father-in-law, who was a bleacher in Glasgow. Otherwise he tried to keep his method a secret.[33]

With McGrigor and his wife Annie, he started to scale up the process, and in March 1788, McGrigor was able to bleach 1500 yards of cloth to his satisfaction. About this time Berthollet discovered the salt and sulphuric acid process, and published it so it became public knowledge. Many others began to experiment with improving the process, which still had many shortcomings, not the least of which was the problem of transporting the liquid product. Watt's rivals soon overtook him in developing the process, and he dropped out of the race. It was not until 1799, when Charles Tennant patented a process for producing solid bleaching powder (calcium hypochlorite) that it became a commercial success.

By 1794 Watt had been chosen by Thomas Beddoes to manufacture apparatus to produce, clean and store gases for use in the new Pneumatic Institution at Hotwells in Bristol. Watt continued to experiment with various gases for several years, but by 1797 the medical uses for the "factitious airs" had come to a dead end.[34]

Watt apparatus 3
Scientific apparatus designed by Boulton and Watt in preparation of the Pneumatic Institution in Bristol


Watt combined theoretical knowledge of science with the ability to apply it practically. Humphry Davy said of him "Those who consider James Watt only as a great practical mechanic form a very erroneous idea of his character; he was equally distinguished as a natural philosopher and a chemist, and his inventions demonstrate his profound knowledge of those sciences, and that peculiar characteristic of genius, the union of them for practical application".[35]

He was greatly respected by other prominent men of the Industrial Revolution.[36] He was an important member of the Lunar Society, and was a much sought-after conversationalist and companion, always interested in expanding his horizons.[37] His personal relationships with his friends and partners were always congenial and long-lasting.

Watt was a prolific correspondent. During his years in Cornwall, he wrote long letters to Boulton several times per week. He was averse to publishing his results in, for example, the Philosophical Transactions of the Royal Society however, and instead preferred to communicate his ideas in patents.[38] He was an excellent draughtsman.

James Watt's letters from the Science Museum Library & Archives in Wroughton
James Watt's letters from the Science Museum Library & Archives in Wroughton, near Swindon.

He was a rather poor businessman, and especially hated bargaining and negotiating terms with those who sought to use the steam engine. In a letter to William Small in 1772, Watt confessed that "he would rather face a loaded cannon than settle an account or make a bargain."[39] Until he retired, he was always much concerned about his financial affairs, and was something of a worrier. His health was often poor and he suffered frequent nervous headaches and depression.

Soho Foundry

At first the partnership made the drawing and specifications for the engines, and supervised the work to erect it on the customers property. They produced almost none of the parts themselves. Watt did most of his work at his home in Harper's Hill in Birmingham, while Boulton worked at the Soho Manufactory. Gradually the partners began to actually manufacture more and more of the parts, and by 1795 they purchased a property about a mile away from the Soho manufactory, on the banks of the Birmingham Canal, to establish a new foundry for the manufacture of the engines. The Soho Foundry formally opened in 1796 at a time when Watt's sons, Gregory and James Jr. were heavily involved in the management of the enterprise. In 1800, the year of Watt's retirement, the firm made a total of 41 engines.[40]

Later years

Heathfield Hall, Handsworth by Allen Edward Everitt
An 1835 painting of "Heathfield", Watt's house in Handsworth, by Allen Edward Everitt
James Watt's Workshop
James Watt's workshop

Watt retired in 1800, the same year that his fundamental patent and partnership with Boulton expired. The famous partnership was transferred to the men's sons, Matthew Robinson Boulton and James Watt Jr.. Longtime firm engineer William Murdoch was soon made a partner and the firm prospered.

Watt continued to invent other things before and during his semi-retirement. Within his home in Handsworth, Staffordshire, Watt made use of a garret room as a workshop, and it was here that he worked on many of his inventions.[41] Among other things, he invented and constructed several machines for copying sculptures and medallions which worked very well, but which he never patented.[42] One of the first sculptures he produced with the machine was a small head of his old professor friend Adam Smith. He maintained his interest in civil engineering and was a consultant on several significant projects. He proposed, for example, a method for constructing a flexible pipe to be used for pumping water under the Clyde at Glasgow.[43]

He and his second wife travelled to France and Germany, and he purchased an estate in mid-Wales at Doldowlod House, one mile south of Llanwrthwl, which he much improved.

In 1816 he took a trip on the paddle-steamer Comet, a product of his inventions, to revisit his home town of Greenock.[44]

He died on 25 August 1819 at his home "Heathfield Hall" near Handsworth in Staffordshire (now part of Birmingham) at the age of 83. He was buried on 2 September in the graveyard of St Mary's Church, Handsworth. The church has since been extended and his grave is now inside the church.


On 16 July 1764 married his cousin Margaret Miller (d. 1773), together they had two children, Margaret (1767-1796) and James (1769-1848). In 1791 their daughter married James Miller. their son did not marry. In September 1773 while Watt was working in the Scottish Highlands he learned that his wife Margaret, who was pregnant with their third child, was seriously ill. He immediately returned home but found that his wife had died and their child was stillborn. [3][45]

In 1775 he married Ann MacGregor (d.1832).[45]


He was Initiated into Scottish Freemasonry in The Glasgow Royal Arch Lodge, No.77, in 1763. The Lodge ceased to exist in 1810. A Masonic Lodge was named after him in his home town of Glasgow - Lodge James Watt, No.1215.[46]

Murdoch's contributions

William Murdoch joined Boulton and Watt in 1777. At first he worked in the pattern shop in Soho, but soon he was erecting engines in Cornwall. He became an important part of the firm and made many contributions to its success. A very able man, he made several important inventions on his own.

John Griffiths, who wrote a biography[47] of him in 1992, has argued that Watt's discouraging Murdoch from working with high pressure steam (Watt rightly believed that boilers of the time would be unsafe) on his steam road locomotive experiments delayed its development.[48]

Watt patented the application of the sun and planet gear to steam in 1781 and a steam locomotive in 1784, both of which have strong claims to have been invented by Murdoch.[49] The patent was never contested by Murdoch, however, and Boulton and Watt's firm continued to use the sun and planet gear in their rotative engines, even long after the patent for the crank expired in 1794. Murdoch was made a partner of the firm in 1810, where he remained until his retirement 20 years later at the age of 76.


James Watt's improvements to the steam engine "converted it from a prime mover of marginal efficiency into the mechanical workhorse of the Industrial Revolution".[50] The availability of efficient, reliable motive power made whole new classes of industry economically viable, and altered the economies of continents.[51] In doing so it brought about immense social change, attracting millions of rural families to the towns and cities.

Of Watt, the English novelist Aldous Huxley (1894–1963) wrote; "To us, the moment 8:17 A.M. means something – something very important, if it happens to be the starting time of our daily train. To our ancestors, such an odd eccentric instant was without significance – did not even exist. In inventing the locomotive, Watt and Stephenson were part inventors of time."[52]


Watt was much honoured in his own time. In 1784 he was made a fellow of the Royal Society of Edinburgh, and was elected as a member of the Batavian Society for Experimental Philosophy, of Rotterdam in 1787. In 1789 he was elected to the elite group, the Smeatonian Society of Civil Engineers.[53] In 1806 he was conferred the honorary Doctor of Laws by the University of Glasgow. The French Academy elected him a Corresponding Member and he was made a Foreign Associate in 1814.[54]

The watt is named after James Watt for his contributions to the development of the steam engine, and was adopted by the Second Congress of the British Association for the Advancement of Science in 1889 and by the 11th General Conference on Weights and Measures in 1960 as the unit of power incorporated in the International System of Units (or "SI").

On 29 May 2009 the Bank of England announced that Boulton and Watt would appear on a new £50 note. The design is the first to feature a dual portrait on a Bank of England note, and presents the two industrialists side by side with images of Watt's steam engine and Boulton's Soho Manufactory. Quotes attributed to each of the men are inscribed on the note: "I sell here, sir, what all the world desires to have—POWER" (Boulton) and "I can think of nothing else but this machine" (Watt). The inclusion of Watt is the second time that a Scot has featured on a Bank of England note (the first was Adam Smith on the 2007 issue £20 note).[55] In September 2011 it was announced that the notes would enter circulation on 2 November.[56]

In 2011 he was one of seven inaugural inductees to the Scottish Engineering Hall of Fame.[57]


Watt was buried in the grounds of St. Mary's Church, Handsworth, in Birmingham. Later expansion of the church, over his grave, means that his tomb is now buried inside the church.[58]

The garret room workshop that Watt used in his retirement was left, locked and untouched, until 1853, when it was first viewed by his biographer J. P. Muirhead. Thereafter, it was occasionally visited, but left untouched, as a kind of shrine. A proposal to have it transferred to the Patent Office came to nothing. When the house was due to be demolished in 1924, the room and all its contents were presented to the Science Museum, where it was recreated in its entirety.[59] It remained on display for visitors for many years, but was walled-off when the gallery it was housed in closed. The workshop remained intact, and preserved, and in March 2011 was put on public display as part of a new permanent Science Museum exhibition, "James Watt and our world".[60]

The approximate location of James Watt's birth in Greenock is commemorated by a statue. Several locations and street names in Greenock recall him, most notably the Watt Memorial Library, which was begun in 1816 with Watt's donation of scientific books, and developed as part of the Watt Institution by his son (which ultimately became the James Watt College). Taken over by the local authority in 1974, the library now also houses the local history collection and archives of Inverclyde, and is dominated by a large seated statue in the vestibule. Watt is additionally commemorated by statuary in George Square, Glasgow and Princes Street, Edinburgh, as well as several others in Birmingham, where he is also remembered by the Moonstones and a school is named in his honour.

The James Watt College has expanded from its original location to include campuses in Kilwinning (North Ayrshire), Finnart Street and The Waterfront in Greenock, and the Sports campus in Largs. Heriot-Watt University near Edinburgh was at one time the School of Arts of Edinburgh, founded in 1821 as the world's first Mechanics Institute, but to commemorate George Heriot, the 16th-century financier to King James, and James Watt, after Royal Charter the name was changed to Heriot-Watt University. Dozens of university and college buildings (chiefly of science and technology) are named after him. Matthew Boulton's home, Soho House, is now a museum, commemorating the work of both men. The University of Glasgow's Faculty of Engineering has its headquarters in the James Watt Building, which also houses the department of Mechanical Engineering and the department of Aerospace Engineering. The huge painting James Watt contemplating the steam engine by James Eckford Lauder is now owned by the National Gallery of Scotland.

Watt James Chantrey
Chantrey's statue of James Watt

There is a statue of James Watt in Piccadilly Gardens, Manchester and City Square, Leeds.

A colossal statue of Watt by Chantrey was placed in Westminster Abbey, and later was moved to St. Paul's Cathedral. On the cenotaph the inscription reads, in part, "JAMES WATT ... ENLARGED THE RESOURCES OF HIS COUNTRY, INCREASED THE POWER OF MAN, AND ROSE TO AN EMINENT PLACE AMONG THE MOST ILLUSTRIOUS FOLLOWERS OF SCIENCE AND THE REAL BENEFACTORS OF THE WORLD."

A bust of Watt is in the Hall of Heroes of the National Wallace Monument in Stirling.


Watt was the sole inventor listed on his six patents:[61]

  • Patent 913: A method of lessening the consumption of steam in steam engines – the separate condenser. The specification was accepted on 5 January 1769; enrolled on 29 April 1769, and extended to June 1800 by an Act of Parliament in 1775.
  • Patent 1,244: A new method of copying letters. The specification was accepted on 14 February 1780 and enrolled on 31 May 1780.
  • Patent 1,306: New methods to produce a continued rotation motion – sun and planet. The specification was accepted on 25 October 1781 and enrolled on 23 February 1782.
  • Patent 1,321: New improvements upon steam engines – expansive and double acting. The specification was accepted on 14 March 1782 and enrolled on 4 July 1782.
  • Patent 1,432: New improvements upon steam engines – three bar motion and steam carriage. The specification was accepted on 28 April 1782 and enrolled on 25 August 1782.
  • Patent 1,485: Newly improved methods of constructing furnaces. The specification was accepted on 14 June 1785 and enrolled on 9 July 1785.


  1. ^ a b Although a number of otherwise reputable sources give his date of death as 19 August 1819, all contemporary accounts report him dying on 25 August and being buried on 2 September. The date 19 August originates from the biography The Life of James Watt (1858, p. 521) by James Patrick Muirhead. It draws its (supposed) legitimacy from the fact that Muirhead was a nephew of Watt and therefore should have been well-informed. In the Muirhead papers, 25 August date is mentioned elsewhere. The latter date is also given in contemporary newspaper reports (for example, page 3 of The Times of 28 August) as well as by an abstract of and codicil to Watt's last will. (In the pertinent burial register of St. Mary's Church (Birmingham-Handsworth) Watt's date of death is not mentioned.)
  2. ^ Lira, Carl (2001). "Biography of James Watt". egr.msu.edu. Retrieved 5 July 2010.
  3. ^ a b c d e f Tann, Jennifer (2013) [2004]. "Watt, James (1736–1819)". Oxford Dictionary of National Biography (online ed.). Oxford University Press. doi:10.1093/ref:odnb/28880. (Subscription or UK public library membership required.)
  4. ^ Muirhead, James Patrick (1859). The life of James Watt: with selections from his correspondence (2 ed.). John Murray. p. 10.
  5. ^ Klooster, John W. (2009). Icons of invention: the makers of the modern world from Gutenberg to Gates. Icons of invention. 1. ABC-CLIO. p. 30. ISBN 978-0-313-34743-6.
  6. ^ Dickinson, Henry Winram; Jenkins, Rhys; Committee of the Watt Centenary Commemoration (1927). James Watt and the steam engine: the memorial volume prepared for the Committee of the Watt centenary commemoration at Birmingham 1919. Clarendon press. p. 78. It is difficult to say anything as to Watt's religious belief, further than that he was a Deist.
  7. ^ McCabe, Joseph (1945). "A Biographical Dictionary of Ancient, Medieval, and Modern Freethinkers". Haldeman-Julius Publications. Retrieved 17 August 2012. He made such improvement in the crude steam-engine that had been invented before his time that he is usually described as the inventor. "His many and most valuable inventions must always place him among the leading benefactors of mankind," says the account of him in the Dictionary of National Biography. He was an accomplished man. He knew Greek, Latin, French, German and Italian and was very friendly with the great freethinking French scientists. Andrew Carnegie has written a life of him and describes him as a deist who never went to church.
  8. ^ Muirhead, James Patrick (1859). The life of James Watt: with selections from his correspondence (2 ed.). John Murray. p. 4,7.
  9. ^ Smiles, Samuel (1904). Lives of the Engineers (Popular ed.). London: John Murray. p. 12. Retrieved 9 December 2017.
  10. ^ Annan, Thomas (1868). Illustrated catalogue of the exhibition of portraits on loan in the new galleries of art, Corporation buildings, Sauchiehall Street. Glasgow: Glasgow Art Gallery and Museum. p. 90. Retrieved 4 December 2017.
  11. ^ "James Watt, 1736 – 1819. Engineer, inventor of the steam engine". Scottish National Portrait Gallery. Retrieved 5 December 2017.
  12. ^ Marshall (1925) Chapter 3
  13. ^ Robinson, Eric; McKie, Doublas. Partners in Science: Letters of James Watt and Joseph Black. Cambridge, Massachusetts.
  14. ^ Lumsden, Harry (1912). History of the Hammermen of Glasgow; a study typical of Scottish craft life and organisation. Paisley: A. Gardner. pp. 394–404.
  15. ^ Hills, vol I, pp. 103–15
  16. ^ Torrens, H. S. (2006). "The geological work of Gregory Watt, his travels with William Maclure in Italy (1801–1802), and Watt's "proto-geological" map of Italy (1804)". The Origins of Geology in Italy. Geological Society of America. 411. pp. 179–197. doi:10.1130/2006.2411(11).
  17. ^ Miller, D. P. "True Myths: James Watt's Kettle, His Condenser, and His Chemistry". History of Science. 42 (3): 333–360 [p. 334]. doi:10.1177/007327530404200304.
  18. ^ Musson, A. E.; Robinson, Eric (1969). Science and Technology in the Industrial Revolution. Manchester University Press. p. 80.
  19. ^ a b Muirhead, James Patrick (1858). The life of James Watt: with selections from his correspondence. J. Murray. pp. 74–83. Retrieved 17 August 2011.
  20. ^ a b Frazer, Persifor (1859). Journal of the Franklin Institute. pp. 296–297. Retrieved 17 August 2011.
  21. ^ Dickinson, p. 36
  22. ^ "OS 25-inch 1892–1949". National Library of Scotland. Ordnance Survey. Retrieved 26 October 2017.
  23. ^ Salmon, Thomas James (1913). Borrowstounness and district, being historical sketches of Kinneil, Carriden, and Bo'ness, c. 1550–1850. Edinburgh: William Hodge and Co. pp. 372–376. Retrieved 9 December 2017.
  24. ^ "James Watt's Cottage", CANMORE. Royal Commission on the Ancient and Historical Monuments of Scotland. Retrieved 13 May 2010.
  25. ^ Hills, vol I, pages 180–293
  26. ^ James Watt's Fire Engines Patent Act, 1775 (15 Geo 3 c. 61). At the time, an Act of Parliament was required to obtain a patent.
  27. ^ Brown, Richard (1991). Society and Economy in Modern Britain 1700–1850. London: Routledge. p. 60. ISBN 978-0-203-40252-8.
  28. ^ Hills, vol 3, ch 5 and 6
  29. ^ Roll p. 158
  30. ^ Hills, Vol, 2, pp. 190–211
  31. ^ W.B. Proudfoot, Origin of Stencil Duplicating, p. 21, as quoted at Quaritch.com 12 Oct 13
  32. ^ Hills vol. 3 p. 116.
  33. ^ Hills, vol 3, ch 4
  34. ^ Hills, vol 3, pp. 152–58
  35. ^ Carnegie, Andrew (1905). "10". James Watt. Doubleday, Page and Company. Archived from the original on 8 July 2009.
  36. ^ Carnegie, chap. XI: Watt, the Man
  37. ^ Hills, vol I, pages 42–43
  38. ^ Smiles, Samuel (1865). "Lives of Boulton and Watt: A History of the Invention and Introduction of the Steam Engine". London: John Murray: 286.
  39. ^ Roll, p. 20
  40. ^ Roll, p. 280
  41. ^ Dickinson ch VII
  42. ^ Hills vol 3, pp. 234–37
  43. ^ Hills, vol 3, pp. 230–31
  44. ^ Robert Chambers' Book of Days
  45. ^ a b Biographical Index of Former Fellows of the Royal Society of Edinburgh 1783–2002 (PDF). The Royal Society of Edinburgh. July 2006. ISBN 978-0-902198-84-5.
  46. ^ Famous Scottish Freemasons. The Grand Lodge of Antient Free and Accepted Masons of Scotland. 2010. Pp.72-73. ISBN 978-0-9560933-8-7
  47. ^ John Griffiths; The Third Man, The Life and Times of William Murdoch 1754–1839 Illustrated with Black-and-white photographic plates and diagrams with Bibliography and Index; Andre Deutsch; 1992; ISBN 0-233-98778-9
  48. ^ Jarvis, Adrian (1997). Samuel Smiles and the construction of Victorian values. Sutton. p. 82. ISBN 978-0-7509-1128-3.
  49. ^ Day, Lance; McNeil, Ian (2003). Biographical Dictionary of the History of Technology. Routledge. p. 878. ISBN 978-0-203-02829-2.
  50. ^ Anderson, Anthony (3 December 1981). "Review: James Watt and the steam engine". New Scientist: 685.
  51. ^ Prasad, B. K. (2003). Urban development: a new perspective. Sarup and Sons. p. 56. ISBN 978-81-7625-352-9.
  52. ^ Ryan, Patrick (5 July 1973). "The last word on... The early and the late". New Scientist.
  53. ^ Watson, Garth (1989). The Smeatonians: The Society of Civil Engineers. Thomas Telford. ISBN 0-7277-1526-7.
  54. ^ Dickinson, pp. 197–98
  55. ^ Steam giants on new £50 banknote, BBC, 30 May 2009, retrieved 22 June 2009
  56. ^ Heather Stewart. "Bank of England to launch new £50 note". The Guardian.
  57. ^ "Scottish Engineering Hall of Fame". engineeringhalloffame.org. 2012. Retrieved 27 August 2012.
  58. ^ Kelly, E.R (1878). The Post Office Directory of Birmingham. London: Kelly and co. p. 176.
  59. ^ "Garret workshop of James Watt". Makingthemodernworld.org.uk. Retrieved 12 March 2011.
  60. ^ "James Watt's legendary 'magical retreat' to be revealed at Science Museum". (Press Release). Science Museum. 1 March 2011. Archived from the original on 25 March 2011. Retrieved 25 March 2011.
  61. ^ Hills, vol 3, p. 13


  • "Some Unpublished Letters of James Watt" in Journal of Institution of Mechanical Engineers (London, 1915).
  • Carnegie, Andrew, James Watt University Press of the Pacific (2001) (Reprinted from the 1913 ed.), ISBN 0-89875-578-6.
  • Dickinson, H. W. (1935). James Watt: Craftsman and Engineer. Cambridge University Press.
  • Dickinson, H. W. and Hugh Pembroke Vowles James Watt and the Industrial Revolution (published in 1943, new edition 1948 and reprinted in 1949. Also published in Spanish and Portuguese (1944) by the British Council)
  • Hills, Rev. Dr. Richard L., James Watt, Vol 1, His time in Scotland, 1736–1774 (2002); Vol 2, The years of toil, 1775–1785; Vol 3 Triumph through adversity 1785–1819. Landmark Publishing Ltd, ISBN 1-84306-045-0.
  • Hulse David K. (1999). The early development of the steam engine. Leamington Spa, UK: TEE Publishing. pp. 127–152. ISBN 1-85761-107-1.
  • Hulse David K. (2001). The development of rotary motion by steam power. Leamington, UK: TEE Publishing Ltd. ISBN 1-85761-119-5.
  • Marsden, Ben. Watt's Perfect Engine Columbia University Press (New York, 2002) ISBN 0-231-13172-0.
  • Marshall, Thomas H. (1925), James Watt, Chapter 3: Mathematical Instrument Maker, from Steam Engine Library of University of Rochester Department of History.
  • Marshall, Thomas H. (1925) James Watt, University of Rochester Department of History.
  • Muirhead, James Patrick (1854). Origin and Progress of the Mechanical Inventions of James Watt. London: John Murray.
  • Muirhead, James Patrick (1858). The Life of James Watt. London: John Murray.
  • Roll, Erich (1930). An Early Experiment in Industrial Organisation : being a History of the Firm of Boulton & Watt. 1775–1805. Longmans, Green and Co.
  • Smiles, Samuel, Lives of the Engineers, (London, 1861–62, new edition, five volumes, 1905).
Related topics
  • Schofield, Robert E. (1963). The Lunar Society, A Social History of Provincial Science and Industry in Eighteenth Century England. Clarendon Press.
  • Uglow, Jenny (2002). The Lunar Men. London: Farrar, Straus and Giroux.

External links

Boulton and Watt

Boulton & Watt was an early British engineering and manufacturing firm in the business of designing and making marine and stationary steam engines. Founded in the English West Midlands around Birmingham in 1775 as a partnership between the English manufacturer Matthew Boulton and the Scottish engineer James Watt, the firm had a major role in the Industrial Revolution and grew to be a major producer of steam engines in the 19th century.

Centrifugal governor

A centrifugal governor is a specific type of governor with a feedback system that controls the speed of an engine by regulating the flow of fuel or working fluid, so as to maintain a near-constant speed. It uses the principle of proportional control.

Centrifugal governors were invented by Christiaan Huygens and used to regulate the distance and pressure between millstones in windmills in the 17th century. In 1788, James Watt adapted one to control his steam engine where it regulates the admission of steam into the cylinder(s), a development that proved so important he is sometimes called the inventor. Centrifugal governors' widest use was on steam engines during the Steam Age in the 19th century. They are also found on stationary internal combustion engines and variously fueled turbines, and in some modern striking clocks.

A simple governor does not maintain an exact speed but a speed range, since under increasing load the governor opens the throttle as the speed (RPM) decreases.

Heathfield Hall

Heathfield Hall (sometimes referred to as Heathfield House) was a house in Handsworth, Staffordshire (the area became part of Birmingham in 1911), England, built for the engineer James Watt.

In 1790, Watt's business partner Matthew Boulton recommended to Watt his friend, the architect Samuel Wyatt, who had designed Boulton's home, Soho House, in 1789. Watt commissioned Wyatt to design Heathfield Hall.

Watt died in the house in 1819, and was buried at nearby St Mary's Church. His garret workshop was then sealed, and few people were ever allowed to visit it. The contents - over 8,300 objects, including the furniture, window, door and floorboards - were removed in 1924 and used to recreate the room at The Science Museum in London, where they may still be viewed.

After a series of subsequent owners who had slowly sold off the associated lands for development of semi-detached villas, in the 1880s engineer George Tangye bought Heathfield Hall. He lived in the house until his death in 1920. After his family sold the house, from 1927 the hall was demolished and the lands redeveloped.What was the Heathfield Estate is now the land that comprises West Drive and North Drive in Handsworth, developed in the 1930s with a number of arts and crafts and moderne-style houses.


Horsepower (hp) is a unit of measurement of power, or the rate at which work is done. There are many different standards and types of horsepower. Two common definitions being used today are the mechanical horsepower (or imperial horsepower), which is about 745.7 watts, and the metric horsepower, which is approximately 735.5 watts.

The term was adopted in the late 18th century by Scottish engineer James Watt to compare the output of steam engines with the power of draft horses. It was later expanded to include the output power of other types of piston engines, as well as turbines, electric motors and other machinery. The definition of the unit varied among geographical regions. Most countries now use the SI unit watt for measurement of power. With the implementation of the EU Directive 80/181/EEC on January 1, 2010, the use of horsepower in the EU is permitted only as a supplementary unit.

J. J. Watt

Justin James Watt (born March 22, 1989) is an American football defensive end for the Houston Texans of the National Football League (NFL). He was drafted by the Texans with the 11th pick in the first round of the 2011 NFL Draft, and played college football at Wisconsin.

Watt received the AP NFL Defensive Player of the Year Award three times in his first five seasons. Although primarily a defensive end, he occasionally shifts to defensive tackle in some situations. He has also taken snaps on offense, catching three touchdown passes during the 2014 season. In 2014, Watt became the first player in NFL history to record two 20+ sack seasons in a career. He holds the Texans' franchise records for both sacks and forced fumbles. In 2017, Sports Illustrated named Watt its Sportsperson of the Year.

James Watt (Royal Navy officer)

Surgeon Vice-Admiral Sir James Watt KBE FRCS (19 August 1914 - 28 December 2009) was a British surgeon, Medical Director-General of the Royal Navy, 1972–1977 and maritime historian.

He was born in Morpeth, Northumberland and was educated at the King Edward VI School there, before entering Durham University, where he qualified in medicine in 1938.He started work as a house surgeon at Ashington Hospital, Northumberland and as resident medical officer at Princess Mary Maternity Hospital, Newcastle upon Tyne. When the Second World War started he joined the Royal Navy, spending most of the time in the Far East, the North Atlantic and the Pacific. When the war finished he continued his medical career at Guy's Hospital, London and the Royal Victoria Hospital, Newcastle-upon-Tyne, but then rejoined the Navy as a surgical specialist.Posted initially to Royal Naval Hospital, Haslar, he also saw service in Korea, Northern Ireland and Hong Kong. He was promoted to Consultant in Surgery in 1956 and became the first joint Professor of Naval Surgery in 1965 with the rank of Surgeon Captain. He became a Surgeon Rear-Admiral when appointed Dean of Naval Medicine and Medical Officer in charge of the Institute of Naval Medicine in 1969 and was further promoted to Surgeon Vice-Admiral when appointed Medical Director-General of the Navy. He was knighted KBE in 1975.He was elected President of the Medical Society of London (1980–81) and President of the Royal Society of Medicine (1982-1984).Watt was President of the Smeatonian Society of Civil Engineers for 1996. He was also the President of the Smeatonian Society of History at the University of Calgary.

He was a Visiting Fellow at University House, the Australian National University, Canberra.

He was also a historian with a particular interest in medicine at sea in the age of sail. His publications include,

"Health and Settlement 1789-95; Life and death in the colony's early years," Australian and New Zealand Journal of Surgery, 59 (1989) 923-31

"James Ramsay, 1733-1789: Naval surgeon, Naval Chaplain and Morning Star of the Anti Slavery Movement", The Mariner's Mirror, 81 (2) 1995, 156-170

"Naval and civilian influences on eighteenth-and-nineteenth-century medical practice," The Mariner's Mirror, 97 (1) February 2001, 148-166

"Surgery at Trafalgar," The Mariner's Mirror, 91 (2) May 2005, 251-65

James Watt (loyalist)

James Watt also known as Tonto (born 21 September 1952) is a former Northern Irish loyalist who was the top bomb maker for the Ulster Volunteer Force (UVF) in the mid-1970s. In 1978, Watt was convicted and given nine separate life sentences for murder and attempted murder. These included bombings which killed a ten-year-old boy and two teenagers in two attacks carried out in April 1977 as a part of a UVF bombing campaign against republicans.

Following his release from prison in 1989 he left the organisation and in 1995 became a preacher having embraced Born-again Christianity while serving his sentence.

James Watt College

The James Watt College was a further education college in Greenock, Scotland. It is now part of West College Scotland. There were also campuses in Largs and Kilwinning which now form part of Ayrshire College as the result of the merger with Kilmarnock College and Ayr College.

James Watt International Gold Medal

The James Watt Medal is an award for excellence in engineering established in 1937, conferred by the Institution of Mechanical Engineers in the United Kingdom. It is named after Scottish engineer James Watt (1736–1819) who developed the Watt steam engine in 1781, which was fundamental to the changes brought by the Industrial Revolution in both his native Great Britain and the rest of the world.

James Watt junior

James Watt Junior, FRS (5 February 1769 – 2 June 1848) was a Scottish engineer, businessman and activist.

Lap Engine

The Lap Engine is a beam engine designed by James Watt, built by Boulton and Watt in 1788. It is now preserved at the Science Museum, London.

It is important as both an early example of a beam engine by Boulton and Watt, and also mainly as illustrating an important innovative step in their development for its ability to produce rotary motion.The engines name comes from its use in Matthew Boulton's Soho Manufactory, where it was used to drive a line of 43 polishing or lapping machines, used for the production of buttons and buckles.

Lesley Laird

Lesley Margaret Laird (born 15 November 1958) is the Deputy Leader of the Scottish Labour Party and the MP for Kirkcaldy & Cowdenbeath. Laird narrowly defeated the sitting MP, Roger Mullin of the SNP by 259 votes at the 2017 general election.A councillor since 2012, Laird is the former deputy leader of Fife Council, where she also held the administration portfolio for economy and planning.

Parallel motion

The parallel motion is a mechanical linkage invented by the Scottish engineer James Watt in 1784 for the double-acting Watt steam engine. It allows a rod moving practically straight up and down to transmit motion to a beam moving in an arc, without putting significant sideways strain on the rod.

Raymond Heacock

Raymond L. Heacock (January 9, 1928 – December 20, 2016) was an American engineer who spent his career at NASA's Jet Propulsion Laboratory where he worked on the Ranger program in the 1960s and on the Voyager program in the 1970s and 1980s. A Caltech engineering graduate, he was the winner of the James Watt International Medal for 1979.

Smethwick Engine

The Smethwick Engine is a Watt steam engine made by Boulton and Watt, which was installed near Birmingham, England, and was brought into service in May 1779. Now at Thinktank, Birmingham Science Museum, it is the oldest working steam engine and the oldest working engine in the world.


The watt (symbol: W) is a unit of power. In the International System of Units (SI) it is defined as a derived unit of 1 joule per second, and is used to quantify the rate of energy transfer. In dimensional analysis, power is described by .

Watt's linkage

Watt's linkage (also known as the parallel linkage) is a type of mechanical linkage invented by James Watt (19 January 1736 – 25 August 1819) in which the central moving point of the linkage is constrained to travel on an approximation to a straight line. It was described in Watt's patent specification of 1784 for the Watt steam engine. It is also used in automobile suspensions, allowing the axle of a vehicle to travel vertically while preventing sideways motion.

Watt steam engine

The Watt steam engine, alternatively known as the Boulton and Watt steam engine, was the first practical steam engine and was one of the driving forces of the industrial revolution. James Watt developed the design sporadically from 1763 to 1775 with support from Matthew Boulton. Watt's design saved significantly more fuel compared to earlier designs that they were licensed based on the amount of fuel they would save. Watt never ceased developing the steam engine, introducing double-acting designs (with two cylinders) and various systems for taking off rotary power. Watt's design became synonymous with steam engines, and it was many years before significantly new designs began to replace the basic Watt design.

The first steam engines, introduced by Thomas Newcomen in 1712, were of the "atmospheric" design. Steam was introduced into a cylinder which was then cooled by a spray of water. This caused the steam to condense, forming a partial vacuum in the cylinder. Atmospheric pressure on the top pushed the piston down. Watt noticed that the water spray also cooled the cylinder itself, and it required significant amounts of heat to warm it back up to the point where steam could enter the cylinder without immediately condensing again. Watt addressed this by adding a separate water-filled cylinder which was opened once the main cylinder was filled. The steam entered the secondary cylinder and condensed, drawing remaining steam from the main cylinder to continue the process. The end result was the same cycle as Newcomen's design, but without any cooling of the main cylinder which was immediately ready for another stroke. Watt worked on the design over a period of several years, introducing the condenser and improvements to practically every part of the design, notably a lengthy series of trials on ways to seal the piston in the cylinder. All of these changes produced a more reliable design which used half as much coal to produce the same amount of power.The new design was introduced commercially in 1776, with the first example sold to the Carron Company ironworks. Watt continued working to improve the engine, and in 1781 introduced a system using a sun and planet gear to turn the linear motion of the engines into rotary motion. This made it useful not only in the original pumping role, but also as a direct replacement in roles where a water wheel would have been used previously. This was a key moment in the industrial revolution, since power sources could now be located anywhere instead of, as previously, needing a suitable water source and topography. Boulton began developing a multitude of machines that made use of this rotary power, developing the first modern industrialized factory, the Soho Foundry, which in turn produced new steam engine designs. Watt's early engines were like the original Newcomen designs in that they used low-pressure steam and most of the action was caused by atmospheric pressure, due mostly to safety concerns. Looking to improve on their performance, Watt began considering the use of higher-pressure steam, as well as designs using multiple cylinders in both the double-acting concept and the multiple-expansion concept. These double-acting engines required the invention of the parallel motion, which allowed the piston rods of the individual cylinders to move in straight lines, keeping the piston true in the cylinder, while the walking beam end moved through an arc, somewhat analogous to a crosshead in later steam engines.

Whitbread Engine

The Whitbread Engine preserved in the Powerhouse Museum in Sydney, Australia, built in 1785, is one of the first rotative steam engines ever built, and is the oldest surviving. A rotative engine is a type of beam engine where the reciprocating motion of the beam is converted to rotary motion, producing a continuous power source suitable for driving machinery.

This engine was designed by the mechanical engineer James Watt, manufactured for the firm Boulton and Watt and originally installed in the Whitbread brewery in London, England. On decommissioning in 1887 it was sent to Australia's Powerhouse Museum (then known as the Technological, Industrial and Sanitary Museum) and has since been restored to full working order.

Scientists whose names are used as units
SI base units
SI derived units
Non-SI metric (cgs) units
Imperial and US customary units
Non-systematic units

This page is based on a Wikipedia article written by authors (here).
Text is available under the CC BY-SA 3.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.