Description:Matthew Boulton had come to Soho in search of water power and quickly rebuilt a four-year old mill by 1762. For the next twelve years the water wheel in the mill was the only source of power at the Manufactory. This power was also limited to the mill itself and was not distributed around the other workshops. The mill was principally used for polishing and grinding and Boulton had to lease Holford mill for metal rolling. There was insufficient water to run the machinery, particularly in the summer and Boulton was desperate to improve the situation.
When Boulton heard of James Watt’s improved steam engine, he quickly realised how it could be applied at Soho. The first working James Watt steam engine in the world (‘Old Bess’) was installed below the water wheel so that its water could be pumped back to the mill pool via the canal in front of the ‘principal building.’ A culvert led from the canal to the water wheel and the water cycle was repeated. ‘Old Bess’ can be seen in The Science Museum, London.
It was not until the early 1780s that that rotary motion was applied to new Watt engines in order to run machinery (the famous ‘Sun-and-Planet’ gear). The first rotary engine was put to work powering a lathe and a drill in the very small establishment that was the Boulton and Watt Engine Works at this time. In 1788 a steam engine was installed in the rebuilt water mill to run laps (polishers) and the presses for cutting out coin blanks. This is also on display in the Science Museum, London (The ‘Lap Engine’). In the same year another steam engine was connected to the coining presses in the new Soho Mint.
In 1802-4 William Murdoch installed three small engines of his own design to power the lathes and drills in an expanded Engine Works. In many of the Manufactory workshops, however, there was never any power and work was done using the strength and skill of the workers or by hand- or foot-controlled machines such as presses and stamps. The water wheel in the mill continued to be used into the 1850s for rolling metal.