Heritage and Landscape

The Soho Manufactory, Mint and Foundry, West Midlands: Where Boulton, Watt and Murdoch made History

The Soho Manufactory, Mint and Foundry, West Midlands: Where Boulton, Watt and Murdoch made History by George Demidowicz, published by Historic England and Liverpool University Press in February 2022, provides a comprehensive analysis of the ground-breaking historic industrial complex, created to the west of Birmingham in the eighteenth century and associated with 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 (figure 1). Together they played a key role in the Industrial Revolution, achieving many world ‘firsts’: the first working Watt steam engine, the first steam-engine powered mint and the first purpose-built steam engine manufactory (the Soho Foundry), which was the first factory to be lit by gas, to name but a few. Existing literature focuses largely on the biographies of the people involved in the venture, primarily Boulton and Watt, or the products they manufactured. The place – the Soho complex – has attracted comparatively little attention. This volume is the first to concentrate on the buildings themselves, analysing not only their physical origins, development and eventual decline, but also their water and steam power systems.  An interdisciplinary approach has been employed combining archival research in the magnificent Soho collection at the Library of Birmingham with the results of archaeological excavations. The volume is profusely illustrated; over 290 figures altogether include 70 original reconstruction plans and drawings by the author and a great deal of archival material, most published for the first time.

Figure 1: Location plan of the three Soho industrial sites. Courtesy of George Demidowicz.

A list of contents is provided at the end of the blog post, but a detailed analysis is beyond the scope of this blog and a way of selecting some of this material is to describe how the research came about, evolved and how certain discoveries were made.

My research began many years ago with the Soho Manufactory. Having initially been commissioned by Birmingham Museum to research for an exhibition on the water mills on the River Cole on which their branch museum, Sarehole Mill, is located, my interest widened to include watermills elsewhere in Birmingham. I was intrigued by the fact that the Soho Manufactory on the Hockley Brook, associated with Matthew Boulton and James Watt had a water wheel operating almost to the end of its life in the 1850s. The well-known illustration of the Soho Manufactory, with the majestic Palladian silver and plated works (the ‘principal building’ [figure 2]) dominating the view blocks the view of the water mill located in the main complex of industrial buildings to its rear. The steep slope and pool that can be seen to the right, however, hint that there was potentially the reservoir and head of water that all such mills needed.

Figure 2: The classic view of the Soho Manufactory c. 1798. Courtesy of British Library, King George III collection, 82-n

The famous partnership of Boulton & Watt was forged initially to sell the rights to erect Watt’s improved engine and then after 1795 to manufacture the complete engines themselves. But Matthew Boulton’s immediate motivation in persuading James Watt to leave Scotland and join him at the Manufactory was to solve the normal problems suffered by water mills: floods, drought in the summer and winter freezes. Any of these could stop the mill from operating.

Figure 3: ‘Old Bess’ Science Museum, London. Courtesy of Science Museum, London.

James Watt’s first working steam engine in the world is well known, but not within the Soho context; it graces the steam engine gallery at the Science Museum where it has been a prize exhibit since the 1860s. What was not common knowledge before this research began is how this water pumping engine was employed at the Soho Manufactory. There is no extant documentation that describes its function. It was only through examining various maps and plans of the Manufactory, and in particular, the bodies of water that were a significant feature of its layout that it was deduced that the engine was located to intercept the mill’s tail race and pump its water back to the head race. James Watt’s Kinneil engine, brought to Soho in 1774, was in fact a water-returning engine aiding the primary source of power at the Manufactory at the time – a water mill. In 1774 its 18-in cylinder was replaced by a 33-in cylinder and became affectionately known as ‘Old Bess’ (figures 3 and 5).

The Soho Manufactory has many more images than complete plans of its layout (of which there are only two). With views of the front and rear, I thought it was worth attempting a 3-D reconstruction for about the year 1805 when it had reached its maximum extent. This was drawn as an axonometric projection raised on a composite plan compiled from several sources (figures 4 and 5).

Figure 4: The composite plan of the Soho Manufactory c.1805. Courtesy of George Demidowicz.

The resulting axonometric was useful in its own right as a graphic representation of the lost Soho Manufactory, completely demolished by 1863, but it also best illustrates the water circulation system that integrated Soho Mill with the James Watt steam pumping engine.

Figure 5: Axonometric projection of the Soho Manufactory c.1806, showing the mill water circulation. Courtesy of George Demidowicz.

Water was taken in the normal way as a head race from the mill pool and passed under a road into a ‘canal’ that was both an aesthetic as well as a functional feature lying below the terrace fronting the principal building. A culvert in the terrace wall carried water below the principal building and its rear yard and over a major break of slope, which I have called the ‘Great Bank’ for convenience, and then along a timber trough (pentrough) to the water wheel. The water left the wheel, having completed its work by means of potential energy, travelling along a culverted tail race below the lower yards. About 60m from the wheel the water was intercepted at right angles and led along a culvert to the bottom of the pump operated by the James Watt engine, which lifted the water through 24 ft (7.3m) to a channel that ran along the end of the principal building to connect with the ‘canal’ thereby completing the circuit (see figure 5).

The Great Bank was obscured by buildings that were one-storey high facing the rear of the principal building and three storeys high towards the lower yards. The break of slope is visible at the interconnecting steps, with its distinctive semi-circular form at the top. 

The Soho Mint, the first steam-engine powered mint in the world was positioned about 110m from the Manufactory’s principal building, hidden deliberately within Boulton’s garden buildings for secrecy. The mint, originally constructed in 1788-9 by Boulton, was substantially altered in 1798-9 so that the presses were no longer powered by the engine mechanically but by vacuum power generated by the steam engine. It was this mint that produced the national coinage, the famous cartwheel pennies and twopences.

Figure 6: Cross section of part of the 1824-6 Soho Mint. The underground main pulley connected to the steam engine via a leather belt has been added in pencil on the lower left. Courtesy of Library of Birmingham, Archives and Local Studies collection.

Boulton’s son, Matthew Robinson Boulton, radically reorganised the mint between 1824 and 1826. Detailed plans of the main mint building exist, but not of the complete layout, which included a new trapezoidally-shaped coin cutting out room. I could not originally locate this room in the old mint buildings. The documentation revealed that an underground drive shaft of about 60m  (196ft) in length had been installed. Along with four coining presses it was to be driven by the new steam engine. Pencil additions to one of the cross-section drawings of the altered mint building showed where the main pulley on this drive was located (figure 6). A leather belt from a pulley on the steam engine wrapped round the pulley positioned below ground in an adjacent yard. The orientation of this narrow yard pointed north-westwards to the central bay of a redundant crescent-shaped building once used for making a flexible buckle that could be moved from shoe to shoe, known as a latchet. The central bay of the Latchet Building was trapezoidal in shape and in an instant the location of the new coin cutting out room was revealed!

Figure 7: The Soho Mint 1824-6 showing the underground drive shaft leading from the steam engine at A to the new Cutting out room at N in the former Latchet Building. Courtesy of George Demidowicz.
Figure 8: The drive shaft tunnel excavated by Time Team, Easter 1996. At the far end of the trench a massive stone block can be seen, one of four originally that supported the main pully connected by leather belt running in the offshoot tunnel to the left leading to the steam engine. Another section of the excavated tunnel can be seen in the adjacent garden beyond. Excavations for sand in the early 20th century destroyed the major part of the mint building including the coining press room and steam engine room. Courtesy of George Demidowicz.

Without an extant overall plan of the mint, this deduction, although logical, could not be proved correct. Only archaeological investigations on site could accomplish this, but this would depend on the Soho Mint surviving below ground in an area which had been developed by housing in the 20th century. There was no prospect, however, of excavations taking place here as a condition of planning permission to redevelop. Time Team, the Channel 4 archaeological programme, appeared to be the only means by which a research excavation with such an aim in mind could take. The programme was initially very reluctant to take it on for in three seasons to date (1996) they were more used to open green fields providing great flexibility to open up trenches elsewhere, if a particular location failed. This was the first time that they would be digging in inner-city back gardens, but equally rarely the Soho archive was on hand to compensate and indicate where the buildings and structures were roughly located.  With good local community engagement, gardens were identified which could be dug up with owners’ permission. The results proved to be beyond expectations, uncovering three separate sections of the brick drive shaft tunnel, leading from the steam engine to the cutting out room (figures 7 and 8). Remarkably a small section of the latter’s outside wall was found below patio slabs.

Apart from confirming the position of the underground drive shaft and its termination in the coin cutting out room, the excavations also fixed precisely for the first time the location of the Soho Mint and the Crescent (Latchet) Building (figures 7 and 9). In addition a small excavation uncovered the southern end of the front wall of the principal building at cellar level. It was limewashed on the interior but the cellar floor at considerable depth was not reached for health and safety reasons.

The third Soho site, the Soho Foundry, did not come to my attention until soon after the Time  Team excavations in 1996, just over a century since Averys, the  weighing machine manufactures had taken over the site. There were rumours that the surviving buildings there were threatened by demolition to be extended into the scrap metal yard immediately adjoining to the west. Joining a site visit organised by the new Lunar Society, then recently formed, I was immediately struck by the sight of early Boulton & Watt buildings still standing high. The view before me could not have contrasted more with the image I retained of our digging in residential back gardens only a few weeks earlier to find remains of the Soho Manufactory and Mint where nothing survived above ground.

Figure 9: The site of the Soho Mint lies in rear gardens of houses in South Road, Handsworth. Courtesy of George Demidowicz.

Before this time there was no understanding that the very earliest fabric of the main foundry building dating to 1795-6 still survived. Fortunately its significance was quickly recognised and together with the massive erecting shop with its early cast iron and wrought iron roof constructed by Boulton & Watt in 1847 was spot-listed Grade II in June 1996. These buildings were regraded the following year to II* along with the Boulton & Watt pattern stores which mainly date from 1809 with the wider area being designated a scheduled monument. Demolition had been averted and there was now time to divert attention from the Soho Manufactory and Mint towards researching the history of the Soho Foundry from its modest beginnings in 1795-6 (figure 10) to its maximum extent in the late 19th century and demise as a steam engine works in 1895 (figures 11 and 12).  This led to Sandwell Council commissioning a documentary and archaeological study, completed in 2002. The history section of this report forms the Soho Foundry chapter, the longest chapter in the book.

Figure 10: The Soho Foundry 1795-9: modest beginnings. Courtesy of George Demidowicz.

In 2008 a temporary roof was erected over the main foundry building jointly funded by the then English Heritage (now Historic England), Sandwell Council and Avery Weigh Tronix, the owners of the site. This is a distinctive sight on a journey by train from Birmingham to Wolverhampton.

Figure 11: The Soho Foundry 1854-1895. Reaching its maximum extent in the latter half of the 19th century after James Watt and Co, took possession in 1848, a partnership with no Boulton or Watt connection, the site was sold to Avery’s in 1895, bringing exactly a century of steam engine production to an end. Courtesy of George Demidowicz.

This blog post cannot do justice to the fascinating history of the buildings and power systems of the first-purpose built steam engine manufactory in the world and the reader is referred to Chapter 7 of the book. Its publication has been timely for at long last a buyer of the site has come forward and feasibility studies and proposals for the reuse of the buildings have been prepared. But it is early days… and any reuse of the buildings, including, it goes without saying, heritage interpretation will need considerable funding, and commitment to the regeneration of a much wider area.

In this blog I have space to draw on one significant aspect of the Foundry’s history. It was the first industrial building in the world to be lit by gas (figures 12 and 13). Much has been written about Matthew Boulton and James Watt, but I have a considerable regard for the third more neglected member of the Soho triumvirate – William Murdoch. It is for this reason that his name appears in title of the book. Murdoch was persuaded to return from Cornwall in 1798 where he was erecting engines on behalf of the firm to help rescue the failing boring mill. He had experimented with gas lighting at his home there. In his own words:
“In the year 1798 I removed from Cornwall to Messrs Boulton and Watt and Co’s works for the Manufacture of Steam Engines at the SF and then constructed an apparatus upon a larger scale [than in Cornwall] which during many successive nights was applied to the lighting of their principal building.”

James Watt Jnr provided more detail when recalling events in 1809:
“William Murdoch constructed a retort of iron with a tube from it of about 30 or 40ft in length and to the end he applied burners of various dimensions and gave light during the nigh time to one of the buildings of the SF.”

There are significant additional details in an 1805 memo:
“Murdoch managed to have small gas retorts set up in the SF Laboratory and these were fitted on 12 Dec 1798.”

The Laboratory was listed in an inventory as being ‘in Arch under Foundry for furnaces’ and in later inventories arches were described as being ‘near the Laboratory’.

The brick arches or vaults, originally five in total, still exist at lower ground level on the north side of the main Foundry building and are accessible.  The latter had been built on a north-south slope so that its casting floor lay at upper ground level on the north of which were located the drying stoves. The top of the brick arches formed an exterior platform at upper ground level for the ash to be removed from the rear of the drying stoves (figure 14). A map of c.1800 shows that immediately to the west of the five arches was a single arch orientated east-west rather than north-south (figure 15). It is suspected that this arch or vault might have been William Murdoch’s laboratory in which a retort was placed in 1798 with a pipe leading from it into the foundry to light it on that historic December day.   

The location of this vault has been identified, but it is presently inaccessible, buried beneath the sand of the main casting floor, but could be excavated archaeologically. It could also be reached from lower ground level but a wall would need to be broken through to do so. If it is the laboratory, was the small gas retort left in there (figure 16)?

Figure 14: The drying stoves were emptied of ash onto the ‘outside’ platform built over a series of brick arches. Courtesy of Library of Birmingham, Archives and Local Studies collection
Figure 15: A possible position of William Murdoch’s laboratory installed in 1798. Courtesy of George Demidowicz.
Figure 16: William Murdoch’s gas retort/ Published in Samuel Clegg Jnr, ‘A Practical Treatise on the manufacture and distribution of coal-gas’ (1866)

George Demidowicz’s The Soho Manufactory, Mint and Foundry, West Midlands: Where Boulton, Watt and Murdoch Made History has been named the Winner of the Association for Industrial Archaeology’s 2023 Peter Neaverson Award for Outstanding Scholarship.

Find out more about this book and others published in partnership with Historic England on the Liverpool University Press website.

The Soho Manufactory, Mint and Foundry, West Midland: Table of Contents

List of Illustrations
List of Abbreviations
Chapter 3: THE SOHO MILL
Chapter 5: THE SOHO MINT


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