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Engines and Steam Technology

Poldark Mine Greensplat Engine by Ainsley CocksMore than any other innovations in mining history, it was the landmark technical advances in steam pumping that marked the formative period of the Industrial Revolution in Cornwall and west Devon. By the end of the 18th century, large-scale, deep mining was made possible by the development of this new technology.

There had been experimentation with steam power in Europe in the early 17th century, but the first practical machine specifically for mining use was developed by the Devon engineer Thomas Savery in 1698. Sources suggest that an early example of one of his mine pumps may have been installed at Wheal Vor, Breage, around this time. Savery's machine took the form of a vacuum pump, however, and it was not until Thomas Newcomen combined an earlier cylinder and piston design with Savery's separate boiler that a workable steam engine was created.

Thomas Newcomen and the atmospheric beam engine

The atmospheric engine invented by Devon-born Thomas Newcomen in the early years of the 18th century triggered groundbreaking changes in the Cornish mining industry. These developments would take it from an enterprise limited by what could be achieved using manpower, horse power and water power to a fully industrialised economy that was amongst the earliest both in Britain, and the world. The steam engine at Great Wheal Vor (Breage), probably installed between 1710 and 1714, is thought by historians to be the first such engine on a metal mine and can be taken as the beginning of the Industrial Revolution in Cornwall.

However, for some time Newcomen engines proved to be something of a false hope for Cornish mine adventurers. Their inherent inefficiencies combined with the crippling burden of coal duty had initially made them too expensive a proposition. By 1727, only five Newcomen engines were working in Cornwall and by 1740 there were still only about 20. Despite work by the Yorkshire engineer John Smeaton – which resulted in the doubling of the efficiency of the Newcomen engine – it was proving too fuel-hungry for most Cornish mines.

By 1778 improvements to the infrastructure to support Cornish mining and the abolition of duty on sea-borne coal meant that  there were over 70 Newcomen engines at work when Pryce stated:
“Mr. Newcomen's invention of the fire engine enabled us to sink our mines to twice the depth we could formerly do by any other machinery.”

A depth of around 200m (below adit) approached the limit of the capability of these engines and, though they opened up important new ore-ground to such depths, deeper mining could not take place until the introduction of the more efficient Boulton & Watt engine into Cornwall in 1778.

James Watt and the separate condenser

James Watt (1736-1819) invented the separate condenser in 1769 after working on a model of a Newcomen engine for the University of Glasgow. After going into business with manufacturer and entrepreneur Matthew Boulton (1728 – 1809), Watt was able to develop a test engine. The fully developed Boulton & Watt engine was far more powerful than the old Newcomen engines and used around 75% less fuel – making it an invention of huge consequence to Cornwall, a region without its own coal reserves.

Boulton & Watt’s first engine in Cornwall was at the Chasewater Mine (later part of Wheal Busy, Chacewater) in 1778. Over the next four years, 40% of the Boulton & Watt engines built were destined for Cornish mines. By 1783, 21 of the new engines were at work in the county with only one Newcomen engine still operating. By 1790 the number of Boulton & Watt engines working in Cornwall had increased to 45 and by 1800 mines were able to attain depths of around 300m below adit.

However, Boulton & Watt enforced strict patents on their technology and also put in place lucrative licensing agreements with mine owners who installed their engines. In Cornwall, this gave engineer Richard Trevithick (1771 – 1833) the impetus to experiment with different ways to reduce the fuel consumption and increase the efficiency of existing beam engines used to pump water from mines.

Richard Trevithick and the Cornish engine

Trevithick recognised high-pressure steam as the key to more powerful and portable engines – for uses such as the steam locomotive, steam ship and steam car.

Richard Trevithick of Camborne is Cornwall’s most famous engineer. He is credited with the introduction of high-pressure steam and a series of historic innovations. Putting aside the doubts of previous engineers about wear and tear and safety, Trevithick recognised high-pressure steam as the way ahead; the key to the development of more powerful, and portable, engines.

The end of the Watt patent in 1800 freed up engineers to market alternative engine designs. Trevithick’s first high-pressure engine was erected at Stray Park (latterly a section of Dolcoath Mine) in 1800 and incorporated a series of radical improvements. Foremost of these was Trevithick’s high pressure wrought iron boiler, which permitted the generation of steam to perhaps 40 or 50 pounds per square inch – around ten times the average working pressure of a contemporary Watt engine (around four pounds per square inch). Trevithick had also developed an engine design to accompany this which was the first to safely take advantage of steam to move a piston at well above atmospheric pressure (14.7 pounds per square inch).

The Cornish engine was to be adopted not only by Cornish and overseas mines but, from 1837, by the new waterworks being constructed to service Britain’s rapidly-growing towns and cities. Cornwall and west Devon foundries expanded to meet the growing demand. They benefited from being in close contact with their market and rapidly became world leaders in engine design, manufacture, transportation and erection.

Beyond mining

Trevithick clearly had a huge influence on mine engines, but another important legacy lay in the potential for small, powerful, self-contained engines – particularly in the field of self-propelled transport. Trevithick’s work laid the foundation for the development of the steam locomotive, the steam ship, the portable engine, the traction engine and the steam car and lorry, for many of which he built prototypes.

The development of efficient high-pressure steam engines with multi-tube boilers effectively freed industry and communications from the limitations of water power, horse power and wind power. At the same time, more economical use of fuel meant freedom of location – making it possible to take and use steam power anywhere.