In the late 18th century John Rennie was an engineer in London, who often acted as an agent for Boulton & Watt, but became an important engineer in his own right. Here is part of his letter and transcript of July 7th 1799 to Messrs Boulton & Watt, confirming the order of a 2hp bell crank engine for William Simonds [Symonds]. The engine was the very first and of a new design – an especially small one, very different from the normal larger hp beam engines. Although it was originally thought that only a few were ever made, at least 100 were produced from 1800 to 1815. This engine was important since it was the first one of the series. James Watt did not think much of the idea but James Watt Junior and William Murdoch did.

It was also the first steam engine used for brewing in Berkshire and it also provided steam for scalding the insides of casks to sterilise them, ensuring that Simonds had better quality beer than local competition. It was also used later in the production of vinegar. Boulton & Watt London Feb.y 7 – 1799

Dear Sirs

I write this to request you will make a Steam Engine of two horses power for Will.m Blackhall Simonds Esq.r of Reading, the Engine to be ready at Reading by the end of next May, – to have Rotative wheels & a Copper Boiler – the latter he will get here so soon as your plans are sent – I will send you a sketch of the situation &c as soon as I could have time to make – in the interim however the Engine can be going on —

And here is the corresponding delivery confirmation from the Boulton & Watt ledgers for the engine in September 1799, All courtesy of the Boulton & Watt archive:

Click on this link to see one in operation! 2hp steam engine movie

All these archives are shown courtesy of the Library of Birmingham, who hold an extensive archive of steam..

There remains only one working engine of this type, in the Science Museum, London.