Age of Invention: Cort Case
Over the course of the last day alone, four separate people have asked for my comment on an article in The Guardian. It is about some new research suggesting that Henry Cort — one of the classic inventor names of the British Industrial Revolution — stole the iron-making improvements he patented in the early 1780s from “76 black Jamaican metallurgists”, many of them enslaved.
Fortunately, I just happened to have read the underlying academic paper by Jenny Bulstrode when it was first published a couple of weeks ago. I read it with great interest because Henry Cort is such a mysterious figure.
The improvement in question was to more easily convert scrap iron into new bar or wrought iron — a higher-quality iron that had had various impurities beaten out of it with hammers — by bundling the scrap together, heating it, and then passing it through grooved rollers, rather than the more usual flat ones, stretching and smoothing the sides and edges of the heated metal so that the resulting bars became “perfectly welded at the edges and throughout” and “completely welded at the sides, without a crack, into one mass, perfectly sound to the centre”.1 There was also a second improvement, though it is seemingly not the one in question, whereby Cort converted cast iron ships’ ballast into wrought iron by mixing it with ladles when it was heated directly in a coal-fired reverberatory furnace — a process later known as puddling, the improvement being that he did this without placing the iron in pots or crucibles to protect it from the impurities in the coal. Together, these improvements came to be known as “rolling and puddling”.
We know so very little about what prompted the discovery of either rolling or puddling, as descriptions became so muddied within just a few years by legal disputes: just five years after his initial patent, it transpired that Cort’s financier, a deputy paymaster of the navy, had actually used government funds rather than his own to fund the venture. This financier died, so the government instead bankrupted Cort and seized his property, including his patents, which they then never enforced. This led to widespread adoption of rolling and puddling by all his competitors in Britain. Although Cort’s friends and supporters eventually secured a government pension for him in recognition of the inventions, he still ended his days as an undischarged bankrupt. Cort thus came to fit the classic narrative mould of the unappreciated and unlucky inventor.
It would certainly be a fitting comeuppance for Cort, if he had in fact all along taken credit for rolling from some of the most oppressed people of the eighteenth century: enslaved Africans in Jamaica. Yet Bulstrode’s new theory for the origin of Cort’s inventions, while suggestive, in my view doesn’t give enough evidence to prove the case. To see why, let’s give Cort yet another day in court.
Bulstrode’s article, linked above, is free to all to read. So you might wish to have a look and judge the case for yourself. But here, in summary, is the actual evidence she presents, shorn of her argumentation and inferences:
Northern Igboland, in modern Nigeria, and parts of the Asante-ruled Gold Coast, in modern Ghana, were major centres in the seventeenth and eighteenth centuries for high-quality ironworking. These regions were also, in the eighteenth century, the source of the overwhelming majority of the people enslaved and then taken across the Atlantic by European slave-traders.
Many of these Africans with ironworking expertise — both free and enslaved — were employed at the major eighteenth-century ironworks in British-ruled Jamaica.
Jamaica lacked ironware, which it needed in large quantities to run and guard sugar plantations. And so any scrap iron at all, including from old ships, was seized upon and converted to new uses. This was despite the fact that since 1719, and reiterated in 1750, Britain’s Parliament had made all iron manufacture in the colonies illegal, so that colonial iron would not compete with that made in Britain.
There was an especially successful ironworks in Jamaica, set up in 1772, which was supported by Jamaica’s House of Assembly despite the British Parliament’s ban. This was run by a John Reeder, who was seemingly prevailed upon to run it despite being “quite ignorant of such a business”. Like many other ironworks, this one used reverberatory furnaces, or “air furnaces”, in which the iron was separated from the coal that fuelled the furnace, by placing it in pots or crucibles. This was to prevent the iron getting infected by the coal’s sulphur, which would make it brittle. Also like many other ironworks, it used rolling mills.
By 1781, Reeder’s ironworks was producing bar, or wrought iron. It was also turning a gigantic profit of £4,000 a year, in today’s terms about £7m. (Bulstrode here suggests that the wrought iron was being derived from the scrap metal, not from the iron ore that Reeder’s works were also smelting, though I have not seen the primary source she cites here, so cannot judge if this is a reasonable inference — let’s assume that her suggestion is correct).
Reeder’s ironworks, according to the evidence of a petition presented later in 1788, had employed about 30 “occasional” white and 76 “principally employed” black workers. Reeder had originally tried to get 60 metallurgists out of England to get the ironworks going, but soon discovered that he could dismiss all but two of them.
Bulstrode notes that many West and Central African societies have used bundles of iron blades — like a kind of iron fasces — as a currency, as dowries, and to mark alliances, providing an illustration of one such bundle made in the 1920s. (It is unclear, as the reference is to a 2018 museum exhibition catalogue that I was unable to find, if such bundles were being used in the eighteenth century.)
Bulstrode notes that sugar mills worked by feeding bundles of sugarcane into grooved rollers, unlike the smooth rollers typically used in ironworks.
One of the workers at Reeder’s ironworks, a free Windward Maroon named Kwasi, was on Christmas Day 1780 baptised with the name John Reeder, which Bulstrode suggests was part of a ritual to give him the power to apprehend a fugitive called Three-Finger Jack. Such a ritual may have involved iron in some way, though we do not know for sure whether it did or, if it did, precisely how. The newly-baptised John Reeder, formerly known as Kwasi, becomes an island-wide celebrity when he kills Three-Finger Jack in January 1781.
In March 1781, some kind of distant relation of Henry Cort’s, John Cort, arrives in Jamaica as the master of the ship Abby. By November 1781 John Cort is in Portsmouth, England.
Henry Cort, a former naval agent who had managed and lent against pay for ships’ crews and the prize money for captured ships, is by 1781 running a struggling ironworks at Fareham, near to Portsmouth, which he had taken over from a debtor of his in c.1777. Cort by 1781 is struggling to profitably meet a contract he had made in 1780 with the Admiralty to recycle a huge amount of scrap iron from mast hoops into new.
In March-May 1782, as a result of French intervention in the War of American Independence, the British government imposes martial law on Jamaica. The new governor closes down John Reeder’s illegal ironworks, on the basis that weapons produced there might be used against the British. The ironworks and machinery are demolished, and any iron or other materials it had stored are taken away for use on British ships, or into Naval stores. Bulstrode notes that Portsmouth is a major Naval store.
In December 1782, Henry Cort boasts in a letter to the steam engineer James Watt that he had invented an improvement to ironmaking, and in January 1783 applies for a patent for bundling the scrap iron, heating it in a reverberatory furnace, and then rolling it through grooved rollers, rather that the more usual smooth rollers. (Cort in June 1784 then patented his puddling process, of converting iron ballast into wrought iron by mixing it with ladles when it was heated directly in a coal-fired reverberatory furnace, without the use of pots. This does not appear to be the process in question, other than Bulstrode noting that the Reeder works had also used reverberatory furnaces. She makes no mention of the presence or lack of pots.)
From this evidence, Bulstrode makes the following claims: that a process was invented at Reeder’s mill for converting scrap iron to make it so commercially successful; that this process was invented collectively by all of the 76 black workers there; that they did so by passing bundled iron fasces through the grooved rollers of a sugar mill, rather than the smooth rollers of an ordinary iron mill; that John Cort heard of this process because of the celebrity of Kwasi for killing Three-Finger Jack; that John Cort told Henry Cort of the process when he was in Portsmouth; that the naval establishment, to which Henry Cort was so connected, had the Reeder ironworks closed down to prevent competition; and that Henry Cort then used the materials confiscated from the ironworks to reverse-engineer the process of bundling scrap iron and passing it through grooved rollers, thus taking credit for it with his patent.
Historians, myself included, often make leaps of intuition from limited evidence. But speculation ought to be explicitly signalled as such, rather than presented as certainty. Especially when that certainty creates a narrative so compelling that it makes major newspaper headlines. Bulstrode’s narrative requires multiple smoking guns to work, none of which are in the evidence she presents.
There is no evidence presented that Reeder’s works were commercially successful because of a newly invented process. Contrast with Cort’s lack of success is not sufficient, as the commercial context was radically different, using different materials, unfree labour, and selling to a different market.
Supposing there were a newly invented process at Reeder’s works, there is no evidence presented of who invented it — perhaps just one or a few of the 76 black workers, or even dare I say it some other workers who were not mentioned in this number. Bulstrode does show that many of these workers were skilled in metallurgy, but skill is not always a prerequisite to invention.
Supposing a new process were invented collectively by all of the 76 black workers, Bulstrode presents no evidence that this specific group used iron bundles at all, let alone in such a process. Nor that the invention was derived from passing iron bundles through grooved sugarcane rollers. The presence of common reverberatory furnaces and common rollers at the ironworks does not prove there was a new process being used there. The fact that grooved rollers were used in Jamaica’s sugar industry and that Cort’s process also used grooved rollers is certainly superficially striking. But Bulstrode makes no comment on the size or shape or configuration of the grooves. They seem, to me at least, to be almost entirely different in function and form.
Below is a sugar mill in Jamaica in the 1790s. There are many such illustrations (here’s another and another) from the decades after, all with similar configurations of grooves. Such mills could have the rollers either vertical or horizontal (but they’re almost always shown vertically). The grooves run along the entire length of the rollers.2
Rollers of iron, by necessity, were always horizontal. But more importantly the grooves always ran around the width, not along the length, of the rollers. They were designed for the heated iron bundles of scrap to be stretched and smoothed through the gaps between the grooves into bars, not crushed to remove husks and squeeze out the juice, as in the case of sugar cane. There are unfortunately no images I could find of Cort’s process itself, and judging by his patent description the upper roller would be flat while the lower one would have a groove, but here are grooved rollers used in the iron industry, as would appear in many technical manuals throughout the nineteenth and into the early twentieth centuries:
But suppose I’m mistaken, and that the grooved rollers used in sugar and iron were identical, both of them having grooves going around the width of the rollers rather than along the length. And suppose that the technique was arrived at in Reeder’s works by passing iron through a sugarcane roller. There is still no evidence that John Cort heard of such a process when in Jamaica, nor that he even met Henry Cort when he returned to Portsmouth, let alone relayed the full and necessary details of it to him.
Supposing that John Cort had indeed managed to get full technical details of a process and then relayed them to Henry Cort, there is no evidence that Henry Cort orchestrated or was in any way involved with the closure of the Reeder works via his Admiralty connections. Nor is there evidence presented that any machinery or tools was seized from the Reeder works, rather than destroyed. Nor that any machinery or tools were transferred specifically to Portsmouth. And even supposing that any machinery or tools from Reeder’s works were transferred to Portsmouth, there is no evidence that they were made available to Cort.
We lack much other evidence of how Cort arrived at his grooved rolling process, but the absence of an alternative narrative is not itself evidence of conspiracy. Frankly, we still know so little in general about nearly all inventions of the period. Some may have been, and almost certainly were taken from abroad — just look at John Lombe stealing the secrets to the Piedmont silk mills in the 1710s. But in this case, we just don’t yet have the evidence either way. And, sadly, we may never do, though I hope that it will inspire more people to study the development of iron.
[Edit, on 28 December 2023: the problems with this paper turned out to be even more significant than I had thought, with some of the sources, upon investigation, not actually showing what was claimed. Unfortunately, the institutional response to pointing out the problems with the evidence has been wanting. For the latest update see here.]
Quoted from Cort’s 1783 patent, as reproduced in R. A. Mott, Henry Cort, the Great Finer: Creator of Puddled Iron (London : Metals Society, 1983), p.97
Note that in some illustrations, the sugarcane wraps around ungrooved rollers, making it appear as though the grooves are around the width. Also note that modern sugar rollers are different. See also John E. Crowley, ‘Sugar Machines: Picturing Industrialized Slavery’, The American Historical Review 121, no. 2 (1 April 2016), pp.403–36