Grace's Guide is the leading source of historical information on industry and manufacturing in Britain. This web publication contains 129,809 pages of information and 204,818 images on early companies, their products and the people who designed and built them.
Boulton and Watt of Soho Foundry, Birmingham.
1762 Matthew Boulton purchased the lease of the Soho, a hamlet in the parish of Handsworth where there was a small house and a mill.
1764 He laid the foundations of his manufacturing establishment there and completed the work the following year for a cost of £9,000. He moved his business Boulton and Fothergill, a partnership with John Fothergill, to the new premises. This became the Soho Manufactory.
1767 Boulton made a steam engine based on the designs of Thomas Savery.
For some years he had contact with James Watt but it was only when Watt's backer, Dr Roebuck, became bankrupt that Boulton took over his share in Watt's engine. In 1774 Watt moved to Birmingham
1775 Watt's patent was extended for twenty-five years to 1800 by act of parliament, and the Boulton and Watt partnership began. The partnership was to make steam engines at the Soho Manufactory, near Birmingham.
The first major market for Boulton and Watt's engines was the mining industry in Cornwall. Boulton saw the opportunity in the growing cotton-spinning industry and urged Watt to develop a rotative engine.
John Wilkinson became the main supplier of cylinders because he could bore them so accurately. The Eagle Foundry and William Whitmore at Birmingham were used to make the heating cases; Izons of West Bromwich supplied tubes; piston rods came from James Spedding of Whitehaven. Heavy parts, such as the flywheels of rotary engines, were obtained locally by the customer.
1783 The first rotary engine was installed at Wilkinson's Bradley Works.
1785 A rotary steam engine was built by Boulton and Watt to grind malt at Whitbread's London brewery. This is now the world's oldest working engine of its type, and is housed at the Powerhouse Museum, Australia. See Boulton and Watt: 1785 Whitbread Engine
1786 the Boulton and Watt assay office in Cornwall was closed
1796 A purpose-built steam engine factory, Soho Foundry, was opened to allow the partners to make and sell complete engines, rather than sub-contracting the manufacture of components and reliance on collecting royalties. Watt effectively retired from active business, though he remained a partner with Boulton and their sons.
By 1800 the number of rotary engines sold per year far exceeded that of reciprocating engines, although smaller in terms of horsepower
1801 Built their factory on fire-proof lines using cast iron beams.
1810 John Southern was admitted as a partner in the firm, and would receive one-sixth of the profits.
1812 Another working Boulton and Watt beam engine, dating from 1812, can be found at Crofton Pumping Station.
1821 Photo and article in The Engineer (11th June 1920) of a beam engine for the Bristol Distilling Co.
A secondhand Boulton and Watt beam engine was advertised for sale in 'The Courier', 12th August 1822. It had a 53"(?) 'steam case cylinder' and cast iron beam, and was standing on the banks of the Somersetshire Coal Canal at Combhay (Combe Hay)
1838-42 See 1839-1842 Marine Engine Makers for details of engines made for the Admiralty.
1843 Oscillating engines of the Sicilian steamer 'Antelope'. 
1849 After James Watt (Junior)'s death, The Soho was let to various persons.
1911 The firm left an extremely detailed archive of its activities, which was given to the city of Birmingham in 1911.