HAVING patented his vastly improved steam engine on April 29, 1769, young James Watt could have been forgiven for thinking that all he had to do was sit back and let the riches flood in. Instead, the inventor had to get to work to prove that his engine was vastly more efficient than the Newcomen Engine – the standard steam engine of the day.

In the same year that he patented his engine, Watt celebrated the arrival of his eldest son, also called James.

Watt had married his cousin Margaret Miller – always known as Peggy – in 1764 and they would have five children in all, with only James Jnr and Margaret Watt, surviving childhood. Peggy Watt died in childbirth in 1772, and it was five years before Watt married again, this time to Ann MacGregor, whose father was a successful manufacturer of dyes and cloth bleacher in Glasgow.

They would have a further two children, and it says much about the health of people at that time that of his seven children in total only one, James Jnr, survived Watt himself.

That Watt accomplished all that he did while losing a wife and six children says much about the sheer dedication of the man. Both his wives were hugely supportive of his work and cared for him in his many bouts of ill health – some of which we would now call depression.

He acknowledged his debt to them in letters which are still extant and was particularly upset at the death of Peggy, as he was working away and absent from their home in Glasgow when it happened.

Before patenting his engine, Watt worked on prototypes with the backing of John Roebuck, the founder of the famed Carron Iron Works. Both Roebuck and Professor Joseph Black invested their own money in Watt’s design and for a while Watt lived and worked in a cottage beside Kinneil House, Roebuck’s home. The ruin of that cottage can still be seen today.

Sadly, iron-working was still in its infancy and Carron could not supply the quality of men and metalwork needed to improve the engine. Watt was no businessman and had accrued plenty of debts due to his spending on materials for his engine, but Roebuck paid them in return for two-thirds of the income from the engine Watt was building. No entrepreneur, Watt was just grateful to be able to carry on working.

The National: The Soho workshopThe Soho workshop

In the early 1770s, he took on numerous surveying and planning projects simply to earn money. They included acting as chief engineer on the Monklands canal, designing a bridge over the Clyde, and surveying the routes of both the Perth and Caledonian Canal, the latter being a particular triumph as the bones of his projections survived into the final design.

He also drew up a plan for deepening the Clyde and making it more navigable for shipping, and although it did not happen until many years later, Watt’s plan formed the basis of the dredging system that made the Clyde one of the great trading and shipbuilding rivers of the world.

While working on the Monklands Canal in 1770, Watt turned his attention as to how his steam engine could power a canal boat.

He realised it would need a propeller at the rear of the boat to be driven by steam and he sketched out a rough design for what is recognisably a screw propeller, more than 60 years before such a development was patented.

It was one of several inventions that Watt made which he had to set aside to concentrate on his steam engine.

It is important to note that for years before and after the 1769 patenting exercise, Watt was spending all the time he could afford on improving his engine. It was not just an overnight invention – it took him decades to get it right.

As Andrew Carnegie noted in his 1897 biography of his fellow Scot: “Watt knew better than any that although his model had been successful and was far beyond the Newcomen engine, it was obvious that it could be improved in many respects—not the least of his reasons for confidence in its final and more complete triumph.

“To these possible improvements, he devoted himself for years. The records once again remind us that it was not one invention, but many, that his task involved.”

Having lost his wife, so too did Watt "lose" his friend and backer, John Roebuck. The most important meeting of James Watt’s life came about because Roebuck went bust. He was forced to sell his share of Watt’s patents and did so to the English foundry-master Mathew Boulton. Watt and Boulton already knew of each other and their meeting turned out to be huge good news for both of them. As we have seen, Watt was no businessman while Boulton was one of the great organisers and managers of the age with his own foundry at Soho near Birmingham.

Watt had already visited Soho and been amazed at the quality of the work done there, so when Boulton bought out Roebuck, the Scot moved quickly south to Soho and a new and hugely successful partnership began.

Boulton and Watt soon began to solve the problems with the engine and in 1776 launched the product that would bear both their names and revolutionise industry. The Boulton and Watt engine was installed in tin mines in Cornwall – Boulton had invested in some mines because he was so confident of Watt’s design – and immediately the new steam engine had a huge impact as it helped drain mines of water much more quickly and cheaply than the Newcomen Engines.

Success loomed, but first they had to beat off all the people trying to copy Watt’s designs which they knew would be out of patent by 1777. Boulton took the case to Parliament and won a 25 year extension to their patent. Even so, they had to fight several court cases throughout the 1780s and 1790s to protect their engine. Some of the cases were against former employees and friends, and though the partnership won the equivalent of several million pounds in today’s money, the litigation exhausted both men. The most celebrated case was against Edward Bull who had worked for the company in Cornwall before starting to build his own engines which, a court eventually decided, infringed Watt’s patents as they had a separate condenser.

Still the inventions came flowing from the firm of Boulton and Watt. At this point it is only right to raise a point with Watt’s legions of supporters. The employment of William Murdoch brought a Scottish inventor of genius in his own right into the company and it has long been argued that Murdoch was the man behind several of the inventions listed as being Watt’s work. Murdoch and this question of attribution is deserving of a column, and so next week Back In The Day will look at his life and career.

Patents were granted to Watt for double-acting and compound engines, for a parallel motion engine, for a throttle valve and a centrifugal governor, all of which improved the Boulton and Watt engine and made them adaptable for all sorts of uses.

For the first time, steam could be used to power engines in just about any location for any purpose.

As well as steam engines, Watt devised a portable copying machine, and it proved highly successful for decades afterwards. He visited the Continent and came back with the idea for chlorine bleaching which he devised along with his father-in-law James McGregor.

At one point the Russian Tsar and Tsarina visited Watt at Soho and tried to lure him to their homeland with promises of a huge salary and massive investment to ‘industrialise’ Russia. Boulton was able to talk him out of it.

Watt even coined and defined the term horsepower, long before he retired officially in 1800.

His inventive mind meant that he did not stop taking an interest in the numerous applications of the Boulton and Watt engine. For instance, he was at first appalled, and then gratified when a fellow Scot, Henry Bell of Helensburgh, put a modified steam engine into a boat he called The Comet which became the world’s first commercial paddle steamer. Watt showed there was no hard feelings in 1816 when he travelled to Greenock on the Comet.

In his later years, Watt also devised machines to copy sculptures and medallions and had his own workshop. We still do not know of all the things he invented because he rarely wrote about them.

It is difficult to overstate just how important steam engines became to the spread of the British Empire in the 19th century. Watt’s technology gave the UK an industrial advantage which Britain did not lose until the start of the 20th century. Steam engines provided the power for the Royal Navy and the vast merchant fleet of the empire.

They also powered those dark satanic mills that spread across England and the industrial heartlands of Scotland. Arguably no single invention changed Scotland as much as the steam engine dreamed up by James Watt on a walk on Glasgow Green.

Don’t take my word for it. Here’s Sir Humphrey Davy on Watt: “He has permanently elevated the strength and wealth of this great empire: and, during the last long war, his inventions and their application were amongst the great means which enabled Britain to display power and resources so infinitely above what might have been expected from the numerical strength of her population.”

Having made his home in the Midlands and become a wealthy man, Watt took considerable interest in the social life of Birmingham where he was a member of the famous Lunar Society of intellectuals.

Over the years, the honours flowed in for Watt who was made a Fellow of both the Royal Society and the Royal Society of Edinburgh. He was famed abroad, too, and was one of only eight Foreign Associates of the French Academy of Sciences.

Curiously he was never given the knighthood that many people thought he deserved.

It did not bother Watt, who remained unfailingly modest all his life. On being congratulated on his success by a member of the House of Lords, Watt replied: “The public only look at my success and not at the intermediate failures and uncouth constructions which have served me as so many steps to climb to the top of the ladder.”

He lived long enough to see Boulton and Watt engines – the company passed to both their sons – begin to transform entire industries, not the least of which was the minting of coinage. On August 19, 1819, James Watt died after a short illness at his home Heathfield Hall in Handsworth. He was buried in nearby St Mary’s Church.

After his death, his legacy led him to being honoured at home and abroad. There are numerous James Watt or Watt Streets around Britain, Heriot-Watt University is named for him (and George Heriot) as is James Watt College in Greenock. He was made an honorary doctor of Glasgow University, and its engineering building is named after him. He has a statue in George Square.

He also has a monument in Westminster Abbey and his own section in London’s Science Museum and Boulton and Watt are particularly well-remembered in Birmingham, where there’s a whole season of events planned this year.

The name of James Watt can also be found on just about every lightbulb in the world, the unit of electrical power called the watt being named after him and confirmed as such in October 1908, at the International Conference on Electric Units and Standards in London.

How’s that for fame?