25 August marks the 200th anniversary of the death of inventor James Watt. To mark the occasion, we have invited a guest post by Debbie Rudder, an expert on Watt, to explore his life and scientific contributions.
James Watt had a deep need to understand how things work, a hunger to improve mechanisms and processes, and skills in mathematics, experimentation, technical drawing and instrument-making. These passions and abilities led to leadership and success in several areas of science and technology.
Watt is mainly celebrated for greatly improving the efficiency of the steam engine and, with Matthew Boulton, converting it from a self-acting pump to a prime mover for industry. The Boulton & Watt in the Powerhouse Museum is the oldest surviving example of their prime mover: an engine that produced rotative motion to literally turn the wheels of industry.
Watt also devised novel engine components and offered early customers a series of upgrades to improve performance. Whitbread’s London brewery, where the Museum’s engine was installed in 1785 and worked for 102 years, took advantage of upgrades that made it more powerful, reduced the amount of attention it required, and reduced the risk of failure of key components. Through all these changes, the engine maintained its original function and overall form, but the changes to its fabric lead some experts to dispute the claim that it is the oldest surviving example.
The engine incorporates four key innovations introduced by Boulton & Watt: the separate condenser (which improved energy efficiency); parallel motion mechanism (which allowed the vertical piston rod to move the end of the beam in an arc); sun-and-planet gears (which converted vertical to circular motion on the output side); and governor (which regulated steam supply so the engine maintained a steady speed). The first three were original equipment, while the governor (which was adapted from flour-mill practice, where it was used to maintain constant distance between millstones) became available as an upgrade in 1788.
As well as being the 200th anniversary of Watt’s death, 2019 is the 250th anniversary of the patent for his key invention, the separate condenser. He arrived at this idea for improving on Thomas Newcomen’s fifty-year-old steam engine design after repairing a model engine and carrying out experiments to understand why it kept stopping. His big idea was to condense each shot of low-pressure steam (after using its energy to move the piston) in a separate vessel, rather than in the cylinder (the heart of the engine, where the piston works); thus energy in the incoming steam wasn’t wasted in reheating the cylinder.
To investigate changes in steam pressure within an engine’s cylinder, he invented a crude form of engine indicator, which his assistant John Southern transformed into the first scientific instrument to present its output as a graph. To produce steam more efficiently and reduce the amount of smoke emitted in the process, he improved the design of boilers and furnaces. To bring steam power to smaller factories and mills, he designed the compact six-column beam engine; one of these engines, imported in 1837 to power a Goulburn flour-mill and brewery, is on display at the Powerhouse.
Another thread of invention saw Watt design one device to help artists create perspective drawings, another to copy documents and a third to copy sculptures. He made perspective drawing devices before he went into partnership with Matthew Boulton. At that time, he ran his own business making scientific instruments; he enjoyed enough success in this venture to employ and train several men to carry out aspects of the work.
While he was heading Boulton & Watt’s drawing office, he invented a machine to make copies of his correspondence and drawings. Having solved his immediate problem, he created a business to mass-produce two versions of this machine: a large one for office use, and a small portable. Machines like these were widely used until the typewriter was invented about a century later.
Developing a machine to copy sculptures was a retirement project. Visiting him in his attic workshop (the contents of which are on display at the London Science Museum) would have been a wonderful experience: watching one of his machines at work would have been rather like seeing a 3D printer for the first time, watching it make things and realising how it works.
When he worked as a surveyor before going into partnership with Boulton, Watt modified his telescope and level to make their use more efficient. As a chemist, he solved technical problems for a ceramic manufacturer, developed new inks for his document-copying machine, experimented with gases, and was one of the first people to realise that water is a compound rather than an element. Watt died on 25 August 1819. He was mourned as ‘the great mechanician’ of his time.
Why do we still study and celebrate the life of Watt? Why is his name well known, while most people have never heard of Newcomen, the inventor of the steam engine? I think the answer is that, while Newcomen engines were a huge boon to Britain’s mining industry, the Boulton & Watt rotative engine revolutionised manufacturing industry and so impacted the lives of many more people.
While the engine is historically highly significant, I don’t think it was a necessary step in the evolution of technology. It was superseded by high-pressure engines lacking the separate condenser, parallel motion, and sun and planet gears. But that package of ideas (plus the governor, which is still an important feature of engines today) brought success to Boulton & Watt and spread their fame across the world. And that success made it impossible for manufacturers in most industries (in Britain, and later in Australia) to succeed unless they invested in steam power.
On 10 August 2019, as part of the Sydney Science Festival, the Powerhouse Museum hosted a lecture about Watt by UNSW Emeritus Professor David Philip Miller, who has written several books and papers that reveal new insights into this much-studied historical figure. Later the same day, his latest book, The life and legend of James Watt, was launched at the Museum.
Written by Debbie Rudder, guest author