When Soho Led the World

These three Soho sites formed a ground-breaking historic industrial complex. They were established in the second half of the 18th century to the west of Birmingham, their fame in no small part due to their association with the great industrial pioneers Matthew Boulton, James Watt, and William Murdoch. The Soho Manufactory (1761-1863) and Soho Mint (1788- early 1850s) were both situated in the historic parish of Handsworth, now in the City of Birmingham. The Soho Foundry (1795-1895) lay in the historic township of Smethwick, now within Sandwell Metropolitan Borough.

The Soho Manufactory, Mint and Foundry played a key role in the Industrial Revolution, achieving many world 'firsts'.

This article is based on research that was carried out on the material history of the three Soho sites, published by Historic England and Liverpool University Press (Demidowicz, 2022). I would like to express my gratitude to Historic England for funding the publication of the book, allowing room for nearly 300 figures. It could not have been accomplished without consulting the magnificent Soho Collection, lodged in the Library of Birmingham. This material was also used to guide the location of archaeological excavations carried out in 1996 in a difficult urban environment.

In 2023 the book received the annual Association of Industrial Archaeology Peter Neaverson Award for outstanding scholarship in industrial archaeology.

The Local dimension

The Soho Manufactory with its smaller neighbour, the Soho Mint, was the largest factory in the Birmingham area in the late 18th century, employing on average between 600 and 700 workers.

This scale of operation was unusual at the time, since industry in Birmingham was then otherwise characterised by small workshops. These were led by a master employing a correspondingly small but skilled workforce, producing metal goods or ‘toys’, as they were called. Most machines were hand and foot- operated, water- power, being used for rolling and slitting metal and sharpening blades, including scythes and swords.

Water power and steam – the first working James Watt steam engine in the world

Matthew Boulton, already a manufacturer of toys, moved to Soho in 1761 in search of water -power, leasing a small mill which he quickly enlarged to allow increased production. Within a few years he boasted that he had erected ‘the largest Hardware Manufactory in the World’ (Demidowicz, 2022, 9). The water source was the diminutive Hockley Brook, from which water was conducted to a mill pool. This can be seen in the classic view of the Soho Manufactory, but the mill itself is hidden by the majestic Palladian silver and plated works (the ‘principal building’) which was constructed between 1765 and 1767.

The famous partnership of Boulton & Watt was initially founded in 1775 to sell the rights to erect Watt’s improved steam engine, making use of a separate condenser, and then, after 1795, to manufacture the complete engines themselves.

Matthew Boulton’s immediate motivation in persuading James Watt to leave Scotland in 1774 and to join him at the Manufactory was to solve the common problems suffered by water mills: floods, drought in the summer and winter freezes. Any of these could stop the mill from operating. 

Boulton had Watt’s improved steam engine with its separate condenser shipped down from Scotland. It was set to work almost immediately to recycle water after use in the mill by pumping it through a newly constructed intercepting culvert back up to a ‘canal’. The Watt engine was, in fact a so-called water-returning engine. Fortunately, in recognition of its significance as the first working Watt engine in the world, it was donated to the Science Museum, London, in 1861.

With no specific documentation available, it was only through examining various maps and plans of the Manufactory, and in particular, the bodies of water which were a significant feature of its layout, that the water circulation system was deduced. This is shown in the figure below, an axonometric projection of the Soho Manufactory in about 1805 when it had reached its maximum extent.

Soho Mint- the first steam-powered mint in the world

The pitiful state of the national coinage, plagued by shortages and counterfeiting, irked Boulton for many years and he finally resolved in the mid-1780s to establish a steam-powered mint to improve the quality of the coinage and increase the rate of production.

With the development of the ‘sun and planet’ crank in the early 1780s, Boulton and Watt steam engines could now provide rotary motion. This offered huge potential for a number of manufacturing applications.

Boulton’s water mill had also been rebuilt in 1785 to provide the extra metal rolling capacity required to produce copper sheeting. The mint was erected in 1788-9 about 110 metres south east of the Manufactory’s ‘principal’ building, hidden deliberately within Boulton’s garden buildings for secrecy. It contained one of Watt’s new steam engines.

Boulton’s technological ambition was matched by his determination to obtain the contract to produce the national coinage, but he was initially disappointed on both counts. The presses in the first Soho mint were driven mechanically by the steam engine, but this motion proved to be too violent and an entirely new and radical method of applying power to the presses was developed. The steam engine was adapted to no longer rotate shafts, cog wheels and cams but instead to produce a vacuum in a tube, the ‘spirit pipe’, to which each press was connected in a complicated arrangement of levers and balancing beams to reduce the impact of the recoil.

Boulton finally signed a contract to produce the national coinage in 1797 and the new vacuum-powered mint was ready by December 1798 to produce the famous but cumbersome and impractical ‘cartwheel’ pennies and twopences. The two distinctly different coining room layouts are illustrated below, showing the mechanical driven presses in a circle, and the vacuum-powered presses in a line. (Click on the images in turn to reveal the full size image).

The Soho Foundry – the first purpose-built steam-engine manufactory in the world

The patent for Watt’s improved steam engine was due to expire in 1800, a development that would allow competitors to produce engines of similar type and quality and challenge Boulton and Watt’s supremacy in the field.

In 1795 the Wilkinson brothers, who made Boulton & Watt’s engine cylinders, quarrelled, and ceased production. The firm had no choice but to build their own manufactory to keep ahead of the competition, drawing all the different stages of production together on a single site.

The Soho Foundry was established in 1795-6 by the Boulton and Watt second-generation, by James Watt junior in particular, in a canal-side location in Smethwick.

It was initially a relatively modest establishment but grew significantly over the next hundred years. The plans above and below demonstrate its growth over a century.

The Soho Foundry – the first manufactory in the world to be lit by gas

In 1798 the inventor of genius, William Murdoch, an employee of Boulton & Watt, the company, was persuaded back from Cornwall, where he was installing Boulton & Watt pumping engines, to rectify the problems of excessive vibration in the boring mill machinery. In this he was successful, introducing for the first time small beamless engines, each dedicated to a boring machine. At the same time, he took the opportunity of furthering experiments on gas lighting that had been carried out at his home in Cornwall.

At the Soho Foundry he erected a small gas retort in his laboratory, connected by ‘a tube of about thirty or forty feet in length’ , leading into the main Foundry building: this became, in December 1798, the first industrial building in the world to be lit by gas (Demidowicz 2022 158).

Steam engine production at Soho Foundry ceased in 1895 and the site was purchased by Avery’s where weighing machine manufacturing continues to the present day. The early Boulton & Watt buildings were abandoned many decades ago, but they survive, and proposals for their repair and restoration are in the earliest stage of development. Unlike the site of the Manufactory and Mint, where nothing remains above ground, the substantial standing buildings at the Soho Foundry are listed Grade II* and the site is also scheduled in recognition of the national importance of the site and its association with one of the great pioneering companies in the nation’s industrial history.

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