[i] Watt's first engine at Kinneil in Scotland[5][6] had been unsuccessful,[7] and the parts were taken down and re-used at Boulton's Soho Manufactory in Birmingham.

[1] The reworked engine was more successful there, and encouraged Boulton to invest further in this developing steam technology and in Watt's inventions.

The Kinneil Engine had been built as a pump, for use in a coal mine, and so was suitable for this new task.

Watt's rotative beam engine had not yet been considered and so the only way to produce rotary work to drive machinery in the Manufactory was by water power.

As early as 1769, Watt was considering the possibility of working steam expansively, as recorded in a letter of 28 May to Dr.

Watt decided to construct a new engine to demonstrate this principle and was confident of the substantial savings in coal consumption to be offered.

Watt was away in Cornwall and Boulton wrote to him, describing the engine's actions as "very fierce".

[13] Boulton favoured further experimentation with cutoff (i.e. valve timing) and in 1779 suggested that a series of more scientific measurements be tried.

With hindsight, Boulton's approach was the more thermodynamically efficient, although this lesson was not fully appreciated by locomotive drivers right to the end of steam power.

Fortunately the most important part of the engine, its cylinder, survived the fire relatively intact.

It was sold for £48, then re-sold for £58 and placed on display on an island in Derrington Pool, outside the metal-rolling works of its new owner, a Mr.

Its name had also shifted from the violent Beelzebub to the rather more friendly Old Bess, indicating a more satisfactory performance.

[16] Reports by both Joseph Harrison, Artificer of the Soho Mint[11] and William Buckle support this.

[8] Firstly the name Beelzebub derives from its violent action when used experimentally for expansive working, an experiment applied to the engine built new in 1777.