Description:Ground plan of double-cylinder engine and mill, Messrs. Davison & Hawksley, Arnold, Nottinghamshire, 1797.
Occasionally Boulton & Watt would alter an existing engine to work on their principals, i.e. they would rebuild it with a separate condenser, air pump, etc. This double-cylinder engine was owned by Messrs. Davison & Hawksley, and it powered their worsted mill at Arnold, near Nottingham. The engine was built by Francis Thompson, a Derbyshire engineer. Dickinson & Jenkins, in 'James Watt and the Steam Engine' (p. 312) say that one of Thompson’s engines powered the first steam-powered worsted mill near Nottingham – it was almost certainly this engine. The firm asked Boulton & Watt to convert the engine to Watt’s principals, but using as much of the old material as possible. Boulton & Watt supplied the air pump, condenser, working gear, parallel motion and sun and planet wheels, which were replaced by a crank in 1798.
This drawing is part of the Archives of Soho, held at Birmingham City Archives [Ref. MS3147/Portfolio/5/149]