Richard Trevithick was a brilliant Cornish mining engineer who invented the first tube system boiler to use high pressure steam, and the world's first self-propelled locomotive. So why for 200 years have people believed James Watt to be the pioneer responsible for those two inventions?  Because Watt and his partner, Matthew Boulton, had the advantage of being shrewd businessmen. 

When James Watt first heard about the new tubular boiler he publicly claimed that Trevithick should be hanged for creating something so lethal. And it was lethal – mainly because the quality of metal available at the time, and the rivets used to bolt the plates together, were simply not strong enough to withstand the enormous pressures.  Trevithick also invented a safety valve for the boiler – after he left one of his engines on a cart outside an inn where he remained drinking for several hours, and it blew up.

High pressure steam cut coal consumption by four fifths, which was a huge financial saving. So after the new Cornish high-pressure steam boiler proved to be successful, Boulton & Watt registered patents which, for over 40 years, made further development by any other engineers impossible. Any attempts to work round these provoked immediate threats of litigation.

Richard Trevithick’s fertile mind meant he invariably worked on several inventions at the same time. This made him hard to pin down to a particular project. He had a quick temper, fell out with his patrons, was invariably short of money, and hopeless at business. 

He married Jane Harvey whose father had established an iron foundry and engineering works in Hayle. All too aware of Richard Trevithick’s poor money management, and anxious that his sister did not suffer, Jane’s brother installed her as manager of his hotel, The White Hart, which she ran while raising six children. This income sustained the family during the sixteen years that Trevithick was in South America. He walked a thousand miles from one side of the continent to the other, maintaining engines and boilers built in Cornwall and sent out to the mines in Chile, Peru and Mexico.

Despite his many remarkable inventions Richard died a pauper.  But at the ‘Trevithick Day’ celebrations in Camborne, a replica of his ‘Puffing Devil,’ the world’s first successful self-propelled vehicle, reminded the crowds of the achievements of this remarkable Cornishman. 

Robert Stirling's hot-air engine

In the C18th and early C18th men working with steam engines were always at risk from exploding boilers. In the first steam-driven locomotives only the driver, stoker, and anyone having the misfortune to be passing by at the time were killed.   

But when high-pressure steam boilers started being used in ships - e.g. in American river steamers driving side-mounted paddlewheels – an exploding boiler meant a death toll of hundreds, and tons of valuable cargo lost.

While work continued on trying to improve the quality of metal and strength of the seals used in constructing high-pressure steam boilers, one man had been exploring a radical alternative.  

Born in Scotland in October 1790, Robert Stirling was one of eight children. His grandfather, Michael Stirling had invented the first rotary threshing machine in 1756, and it was probably from him that Robert inherited his interest in engineering. After a classical education at Edinburgh University, Robert was ordained as a minister of the Church of Scotland in 1816.  This same year he patented his first ‘air’ engine. 

There had been earlier experiments with ‘hot-air’ engines both in France and England so the idea wasn’t new.   What made Stirling’s engine different was his invention of a regenerator, which stored the heat from one cycle for use in the next, making the engine far more efficient. 

His was a closed-cycle engine which meant the same air – first heated then cooled – was used over and over again. No new air was drawn in and none was expelled as exhaust.    

How it worked:  air inside the cylinder was heated by an outside source, a small wood or coal fire.  (In the model above the silver-coloured chamber is the firebox, and in front of the water tower - part of the cooling system - you can see the handle of the shovel on which the fire would be laid.)  This heated air expanded and pushed up the piston. The air then passed through the regenerator to the cold side of the engine where it cooled and contracted, pulling the piston down.  This continual heating and cooling of the air produced the pressure change that pushed and pulled the piston, making the engine run. 

It was beautifully simple, efficient and clean.  But most important of all, because there was no boiler it was totally safe.  In 1818 one of these engines was used as a quarry pump and ran for two years.  

Heavy investment in high-pressure steam meant that the air engine – an invention ahead of its time - was never fully exploited. 

But it gave me a great idea for a book.   

Jane Jackson.