Science Museum, London/ Science & Society Picture Library

Portrait of James Watt (1736-1819) by C.F. Von Breda, 1792. The following year, Watt began litigation against infringers of his separate condenser patent. Already working hard on engine designs (some of which can be seen in the portrait), even more of Watt's time was devoted to legal proceedings, which only concluded six years later.

In 1760, most steam engines were of a type developed by Thomas Newcomen . They consisted of a vertical open-topped cylinder within which a close-fitting piston was hung by a chain attached to a rocking beam. From the other end of the beam, pump rods were attached to a water pump. Steam was admitted to the cylinder at very low pressure, before being rapidly condensed by a jet of cold water to create a vacuum. The unbalanced atmospheric pressure drove the piston down, raising the pump rods and operating the pump.

In 1763-4 James Watt, working as instrument-maker for Glasgow University, carried out experiments on a model Newcomen engine and realised that, although reliable, it consumed a lot of fuel. This was a result of the heating and cooling of the cylinder during each stroke. The answer, which Watt arrived at in 1765, was to condense the steam in a separate condenser, allowing the temperature of the cylinder to remain constant.

This innovation reduced the coal consumption of the Newcomen engine by two-thirds and was widely adopted in places like Cornwall, where mines had to be kept clear of water but coal supplies were at a premium. Patented in 1769, it formed the basis for the partnership established by Watt with Matthew Boulton in 1775 and paved the way for the wider introduction of the steam engine into industry.

Watt would gladly have concentrated on mine pumping engines but for Boulton who, sensing that people were going 'steam mill mad', wrote:

I think that mills{A133}present a field that is boundless and that will be more permanent than these transient mines, and more satisfactory than these inveterate, ungenerous and envious miners and mine lords.

Science Museum, London/ Science & Society Picture Library

A drawing of Watt's 10 horsepower engine, built from 1787 to 1800, from Farey's Treatise on the Stationary Steam Engine (1827). On the left can be seen the 'wagon' boiler in its brick surround, supplying steam to the vertical cylinder (centre left). This drives the flywheel (right) by means of the beam (top).

	Matthew Boulton
	Matthew Boulton (1728-1809) was the son of a wealthy toy manufacturer, and through his father learnt how to establish and successfully manage business ventures. Boulton's father died in 1759 whereupon he moved to the Soho area of Birmingham, rebuilt an old mill and transformed it into the Soho manufactory--in its day the most famous factory in the world. It housed not only workshops but also showrooms, design offices, stores and workers' accommodation. Boulton built his reputation on the manufacture of top quality jewellery, silverware and plated goods. In 1774 he went into business with James Watt, forming what was to be the most important partnership of the Industrial Revolution. Later, Boulton went on to use modern manufacturing methods to revolutionise coinage production.

So, Watt developed a 'rotative' steam engine suitable for driving machinery in factories. James Pickard of Birmingham patented the crank, the easiest means of converting the vertical motion of the piston into the rotary motion of a flywheel, in 1780. Watt was forced to develop an alternative 'sun and planet' gearing system instead. Watt made these engines until 1802, although he also built crank engines from 1794, when Pickard's patent expired.

These engines were well suited to driving the textile mills, and they comprised over 60 percent of the approximately 500 engines built by Boulton and Watt before 1800. However, despite their technical prowess, the take-up of Watt's rotative engine was problematic. Why was this?

Boulton and Watt experienced difficulties keeping up with the demand for steam engines. They took a managerial role, supplying advice, a skilled engine erector and some special parts of the engine, but much else was left to the client to organise. This would be a daunting prospect in any case (for instance, over 40 subcontractors were involved in building the Smethwick engine in 1779), but it was made worse given the general lack of knowledge about steam engines among millowners.

As orders for engines poured in, a shortage of skilled engine erectors, also slowed down work. Watt wrote to a millowner in 1791:

We cannot engage to furnish the engine in less than six months after the date of the order and it may take five weeks to put it together when every thing is upon the spot.

The consequences of this were recorded in a note from a Stockport millowner in 1791 recording that:

There will soon be plenty of orders from this neighbourhood, but you will never get them executed half soon enough.

The client's problems did not end when the engine was complete. Boulton and Watt offered little or nothing by way of after-sales service, so a breakdown (perhaps the fault of an inexperienced engineman) could mean a lengthy stoppage. In July 1788 Richard Gorton, a millowner from Mansfield, wrote:

Our engine goes worse and worse every day, we are never sure of being able to proceed with our weaving{A133} this morning we can hardly keep the steam up & it goes so irregular, that the weavers can do nothing.

While these difficulties were slowly resolved, one insurmountable problem remained the cost of Watt's engine. The initial price was high, starting from around £500, and substantial yearly premiums (amounting to £5 per horsepower capacity per year in the provinces, or six guineas in London) also had to be paid. The premium became a major concern to millowners, particularly if an engine was only to be used part of the year (for example, to work in place of a waterwheel during the dry summer season).

Thus, despite the technical success of their engine, Boulton & Watt's success convincing millowners of its utility was quite limited. Working to the limits of engineering practice at the time, they were handicapped by a lack of skilled labour, mirroring the situation elsewhere in the nascent engineering industry. After 1800 the situation improved; Boulton & Watt began to standardise their engine designs and working procedures, making assembly quicker and easier. But by then circumstances had already conspired to make other, older means of driving factories equally attractive.