James Watt Biography

James Watt James Watt (1736–1819) was a Scottish inventor, mechanical engineer and chemist – he is famous for developing the first steam engine with a wide range of uses. His inventions greatly increased the efficiency of the steam engine and enabled it to become a pivotal part of the Industrial Revolution.

Early life

James Watt was born in Greenock, Scotland on 18 January 1736. Due to ill health as a child, he was mostly educated at home by his mother. He also helped out in his father’s workshops – where he learnt many practical skills of basic engineering.

Pursuing his mechanical and scientific interests, Watt went to Glasgow and then London to be trained in the profession of a mathematical instrument maker. His skills in producing instruments was recognised by members of Glasgow University and he was encouraged to set up a workshop close to the University. Although he never had the funds to study at university properly, he showed an inherent capacity to teach himself. He learnt German and Italian so that he could study more scientific manuals. At university, he became friendly with economist Adam Smith and chemist Joseph Black. Around 1759, one of his university friends Prof. John Robinson talked about the possibility of a steam-driven car. Although impractical with the current state of technology, it sowed a seed of intrigue in the mind of James.

Development of steam engine

Around 1763, Watt came into contact with his first Newcomen steam engine. They had been in use for over 50 years, with no significant development. Without any formal training, he began to learn how they operated and how they could be fixed. At the time, the Newcomen steam engine was the most powerful steam engine on the market, but the inefficiency of this early steam engine meant it was limited to a stationary point in mines.

However, Watt realised that this version of the steam engine was very inefficient because energy was repeatedly being used to heat the cylinder. He decided to try and invent a more efficient alternative. He describes his thought process for implementing a radical change.

“The idea came into my mind that as steam was a gas it would rush into a vacuum, and if I linked the engine’s cylinder to a vessel at low pressure, the steam would rush into it. The steam would condense there and it wouldn’t cool the engine-cylinder. I then saw that I must get rid of the condensed steam from the cylinder.” – Watt

He worked on a model which caused steam to condense inside a separate chamber apart from the piston. He soon had a working model and by 1775 had received a patent called: “A New Invented Method of Lessening the Consumption of Steam and Fuel in Fire Engines.”

Over the next few years, his work on the steam engine was disrupted as he needed to take employment working as a land surveyor. He travelled around Scotland surveying routes for building canals.

Business partnership and expansion

Watt was not adept at business, his first business partner John Roebuck went bankrupt in 1772. But, shortly after, he was able to form a successful partnership with Matthew Boulton – a manufacturer from Birmingham. Boulton & Watt became a successful company – leasing the design and later producing these new steam engines for a variety of purposes from mining to cloth and wool manufacture.


James Watt steam engine

He moved to Birmingham and, over the next six years, continued to improve the steam engine. He wrote to a friend that he became obsessed with the machine.

“I can think of nothing else than this machine” Letter to Dr. Lind, April 29, 1765.

Important inventions included developing a double-action engine so that power was used in both the up and downstroke. He insulated the steam cylinder to increase efficiency. The combined effect of Watt’s improvements was an approximate five-fold increase in the power and efficiency of the steam engine. The new steam engine was developed with a ready market due to the fast industrialising economy. Business thrived as orders flooded in. Early orders tended to be from mine owners – Watt spent much time in Cornwall dealing with mine owners who bought his machines. However, as the steam engine became more sophisticated, Watt and Boulton found new markets on canals, distilleries and cotton mills.


James Watt’s Workshop

Other important developments which Watt worked on included a system of gears which enabled the motion of the steam engine to be converted into rotary motion – in other words, an engine that can turn wheels. In 1788, he developed a centrifugal governor which meant that the power of the steam engine could be regulated and turned up and down. He also developed a throttle, a pressure gauge, throttle valve and indicator. All these minor inventions laid the framework for making the steam train a possibility. The first steam train was built by Richard Trevithick in 1804 and although it was too unreliable to use – it indicated the potential for steam travel, something that appeared infeasible before Watt’s invention.


James Watt

Other inventions

Watt also made other important discoveries and inventions. These included a copying machine and an improved production method for chlorine, a bleaching agent. He developed the concept of horsepower to describe an engine’s power output. (he related power to the equivalent number of horses needed to pull an application). Horsepower was later replaced by a different scientific measure, but in deference to Watt’s contribution the measure of power was called ‘Watt’.

He received significant appreciation during his lifetime. He was a leading member of the Lunar Society in Birmingham – a society devoted to scientific progress and instrumental in the Industrial Revolution. For his efforts, he was made a member of the Royal Society of Edinburgh in 1784 and the Royal Society in 1785.

After his fortune enabled him to retire, he pursued a wide variety of interests from improving oil lamps to measuring distances with a telescope.

Personal life

In 1764, (the year of repairing his first steam engine) he married a cousin Margaret Miller. They had six children together, though she died in 1773. He remarried Ann MacGregor in 1776; they had two children together.


His parents were strict Presbyterians, but Watt did not agree with his parents’ religious outlook on life. He was more inclined towards science. Later in life, he adhered to a Deist outlook – a broad spirituality – not connected with any particular church or religion. He was also a member of the Freemasons.


James Watt died at Heathfield, Birmingham on 25 August 1819, aged 83. He left a will of over £60,000 (approx £80 million in today’s money). He was buried at St Mary’s Church Birmingham alongside Matthew Boulton.


The development of an efficient steam engine transformed industry and society. It helped Great Britain become the world’s first industrialised society leading to an unprecedented pace of economic growth. His steam engine was further refined, but his breakthrough enabled the development of smaller, lighter and more efficient engines that could be used in trains – as opposed to stationary engines which were limited to a static place like in a mine.

Did James Watt invent the steam engine?

No. He did not invent the steam engine, but he did invent a significantly more efficient steam engine that became the basis for the machine that transformed the industrial revolution. Before Watt, the steam engine was very limited. The Newcomen steam engine was invented more than 50 years prior. Watt’s invention enabled it to be used for propelling steam trains amd machines in factories. Therefore, his reputation as the inventor of the steam engine is deserved. Without Watt, the industrial revolution would have been slower to occur.

Citation: Pettinger, Tejvan. Biography of James Watt, Oxford, www.biographyonline.net 23rd May 2010. Last updated 5 February 2020.

1001 Inventions That Changed the World

Book Cover


1001 Inventions That Changed the World at Amazon


Inventors – Famous inventors including Cai Lun, Leonardo da Vinci, Galileo, Thomas Edison, Nikola Tesla, Sir Isaac Newton, James Watt and Samuel Morse.

Inventions that changed the world – Famous inventions that made a great difference to the progress of the world, including aluminium, the telephone and the printing press.

britishIndustrial Revolution (1750s to 1900) The great inventors, entrepreneurs and businessmen of the industrial revolution. Also includes the social activists of the era, such as Charles Dickens.