Age of Invention: The Second Soul, Part I

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Here’s a riddle.

There was a product in the seventeenth century that was universally considered a necessity as important as grain and fuel. Controlling the source of this product was one of the first priorities for many a military campaign, and sometimes even a motivation for starting a war. Improvements to the preparation and uses of this product would have increased population size and would have had a general and noticeable impact on people’s living standards. And this product underwent dramatic changes in the seventeenth and eighteenth centuries, becoming an obsession for many inventors and industrialists, while seemingly not featuring in many estimates of historical economic output or growth at all.

The product is salt.

Making salt does not seem, at first glance, all that interesting as an industry. Even ninety years ago, when salt was proportionately a much larger industry in terms of employment, consumption, and economic output, the author of a book on the history salt-making noted how a friend had advised keeping the word salt out of the title, “for people won’t believe it can ever have been important”.¹ The bestselling Salt: A World History by Mark Kurlansky, published over twenty years ago, actively leaned into the idea that salt was boring, becoming so popular because it created such a surprisingly compelling narrative around an article that most people consider commonplace. (Kurlansky, it turns out, is behind essentially all of those one-word titles on the seemingly prosaic: cod, milk, paper, and even oysters).

But salt used to be important in a way that’s almost impossible to fully appreciate today.

[Before we crack on: because this post is so long, and because of all the illustrations and references, there’s a high risk that this email may end up truncated for some people. If this happens, you can always read the post online by simply clicking here.]

Try to consider what life was like just a few hundred years ago, when food and drink alone accounted for 75-85% of the typical household’s spending — compared to just 10-15%, in much of the developed world today, and under 50% in all but a handful of even the very poorest countries. Anything that improved food and drink, even a little bit, was thus a very big deal. This might be said for all sorts of things — sugar, spices, herbs, new cooking methods — but salt was more like a general-purpose technology: something that enhances the natural flavours of all and any foods. Using salt, and using it well, is what makes all the difference to cooking, whether that’s judging the perfect amount for pasta water, or remembering to massage it into the turkey the night before Christmas. As chef Samin Nosrat puts it, “salt has a greater impact on flavour than any other ingredient. Learn to use it well, and food will taste good.” Or to quote the anonymous 1612 author of A Theological and Philosophical Treatise of the Nature and Goodness of Salt, salt is that which “gives all things their own true taste and perfect relish”. Salt is not just salty, like sugar is sweet or lemon is sour. Salt is the universal flavour enhancer, or as our 1612 author put it, “the seasoner of all things.”

Making food taste better was thus an especially big deal for people’s living standards, but I’ve never seen any attempt to chart salt’s historical effects on them. To put it in unsentimental economic terms, better access to salt effectively increased the productivity of agriculture — adding salt improved the eventual value of farmers’ and fishers’ produce — at a time when agriculture made up the vast majority of economic activity and employment. Before 1600, agriculture alone employed about two thirds of the English workforce, not to mention the millers, butchers, bakers, brewers and assorted others who transformed seeds into sustenance. Any improvements to the treatment or processing of food and drink would have been hugely significant — something difficult to fathom when agriculture accounts for barely 1% of economic activity in most developed economies today. (Where are all the innovative bakers in our history books?! They existed, but have been largely forgotten.)

And so far we’ve only mentioned salt’s direct effects on the tongue. It also increased the efficiency of agriculture by making food last longer. Properly salted flesh and fish could last for many months, sometimes even years. Salting reduced food waste — again consider just how much bigger a deal this used to be — and extended the range at which food could be transported, providing a whole host of other advantages. Salted provisions allowed sailors to cross oceans, cities to outlast sieges, and armies to go on longer campaigns. Salt’s preservative properties bordered on the necromantic: “it delivers dead bodies from corruption, and as a second soul enters into them and preserves them … from putrefaction, as the soul did when they were alive.”²

Because of salt’s preservative properties, many believed that salt had a crucial connection with life itself. The fluids associated with life — blood, sweat and tears — are all salty. And nowhere seemed to be more teeming with life as the open ocean. At a time when many believed in the spontaneous generation of many animals from inanimate matter, like mice from wheat or maggots from meat, this seemed a more convincing point. No house was said to generate as many rats as a ship passing over the salty sea, while no ship was said to have more rats than one whose cargo was salt.³ Salt seemed to have a kind of multiplying effect on life: something that could be applied not only to seasoning and preserving food, but to growing it.

Livestock, for example, were often fed salt: in Poland, thanks to the Wieliczka salt mines, great stones of salt lay all through the streets of Krakow and the surrounding villages so that “the cattle, passing to and fro, lick of those salt-stones”.⁴ Cheshire in north-west England, with salt springs at Nantwich, Middlewich and Northwich, has been known for at least half a millennium for its cheese: salt was an essential dietary supplement for the milch cows, also making it (less famously) one of the major production centres for England’s butter, too. In 1790s Bengal, where the East India Company monopolised salt and thereby suppressed its supply, one of the company’s own officials commented on the major effect this had on the region’s agricultural output: “I know nothing in which the rural economy of this country appears more defective than in the care and breed of cattle destined for tillage. Were the people able to give them a proper quantity of salt, they would … probably acquire greater strength and a larger size.”⁵ And to anyone keeping pigeons, great lumps of baked salt were placed in dovecotes to attract them and keep them coming back, while the dung of salt-eating pigeons, chickens, and other kept birds were considered excellent fertilisers.⁶

Indeed, salt had been used since ancient times as a fertiliser. Contrary to popular belief, when the Romans allegedly destroyed Carthage and salted the earth, such practices in the ancient world were not about rendering the land infertile by making it too saline for anything to grow. You’d need an impossibly large amount of salt to do that. There’s no evidence Carthage was sown with salt at all, but the chosen ancient method of ruining farmland — seemingly practised by Ashurbanipal in the subjugation of Elam, for example — was to sow salt with the seeds of particularly aggressive weeds. Salt was sown not because it sterilised, but the opposite — because it could be so remarkably fructifying.

(While we’re on myths about the Romans and salt: there is an oft-repeated notion that “salary”, from the Latin salarium, comes from Roman soldiers being occasionally paid in salt. This, too, appears to be completely made up — yet another zombie myth to add to the growing list.)

The use of salt for growing crops went back to ancient times — it was recommended in Mesopotamia for growing date palms, for example — and this continued into the sixteenth and seventeenth centuries. Salt-rich sea sand was a widely-used fertiliser in the south-west of England, and the soil that had soaked up the runoff from the Cheshire brine springs was famous for its bounty.⁷ Where salty soils were less easy to get to, seeds could also be steeped in a brine made from common salt before they were sown, allegedly fortifying them against various pests and diseases.⁸ Exactly how effective and widespread was salt in agriculture, and were there periods where it was more in use? It’s unclear, because as far as I can tell nobody has tried to quantify it.

But regardless of whether it was used in agriculture, for preservation, or for cooking, salt was also essential. The human body is constantly losing salt through sweat, and to a certain extent urine, but it tries to keep the blood’s salt concentrations maintained at a certain level. So as the blood loses salt, the body also ejects water to adjust. Ironically, as you lose salt your body responds by drying you out. Without constantly replacing the salt in your body — which is only ever stored for a couple of days at a time — you will at first feel fatigued and a little breathless, but increasingly weak and debilitated, as though sapped of all energy. The slightest exertion would start to bring on cramps, then problems with your heart and lungs, as your body continually shed water. If these did not kill you — and they probably would — you would essentially die through desiccation. The process would be all the faster if you became ill, rendering even the slightest dehydrating fever or bout of diarrhoea utterly lethal.⁹

A population deprived of salt was thus one that was weaker and more prone to disease — and at a time when the vast majority of the economy’s energy supply came from the straining of muscle, both human and animal, that weakness in effect meant a severe energy shortage. Although the main fuels for muscle power were carb-heavy grains like wheat, rye, oats, and rice, the indispensable ingredient to getting the most out of these grains was salt — just as how nuclear power uses uranium as its fuel, but also requires a suitable neutron moderator. A population deprived of salt would quite literally be more lethargic and sluggish, making it less productive and poorer too.

Salt’s unique properties made it a serious tool of state. In 1633 king Charles I’s newly-appointed Lord Deputy for Ireland, Baron Wentworth, advised controlling its salt supply as a way to make the Irish utterly economically dependent on England. Given salt was “that which preserves and gives value to all their native staple commodities” — herrings, butter and beef — then “how can they depart from us without nakedness and beggary?” Salt would be a method of control, and a profitable one too, being “of so absolute necessity” that it could be sold to the Irish at inflated prices without much dampening demand: salt “must be had whether they will or no, and may at all times be raised in price”.¹⁰ Much like economists today, Wentworth saw revenue-raising potential in taxing goods with such unresponsive or ‘inelastic’ demand.

Wentworth’s scheme to control the Irish never came to be. But a great many other countries did choose to tax it. Given a minimum amount of salt had to be consumed by absolutely everyone, monopolising its sale — and levying what was effectively a tax by inflating the price well above the costs of importing or producing it — could function as kind of indirect poll tax, levied more or less per head of both people and livestock, but without any of the administrative hassle of taking and maintaining an accurate census in order to impose such a tax directly.

When compared to other necessities like grain, salt did not need to be traded in especially large quantities either, meaning that its supply could be monopolised with relative ease. And it could not be produced everywhere. Salt tended to be lacking the further you got from the sea coast, unless there happened to be some relatively rare inland sources like salt lakes, brine springs, or rock salt mines. And it could even be lacking on the sea coast where it was either too humid or too cold to get salt cheaply by evaporating seawater using the sun, or where there was insufficient fuel for boiling the brine. These places were thus prone to being charged inflated prices, while the states that controlled places where the costs of production were low — in warmer and drier climes where the salty water of coastal marshes could cheaply be evaporated using only the heat of the summer sun — could extract especially large monopoly profits from the difference. The revenue from controlling solar salt thus became the basis of many kingdoms, some unusually powerful republics, and even empires.

Empires of the Sun

The twelfth-century counts and viscounts of Toulouse and Provence, who ruled the salt marshes along the sunny French Mediterranean coast, discovered that a great many regions were dependent upon them for salt, including many of the lands up the river Rhône, towards Switzerland, and even down the coast towards the northern Italian cities of Genoa and Pisa. Alongside the customs duty these rulers charged on various other export goods — called gabelle, from the Arabic qabālah, meaning tax or tribute — the duties they charged on salt came to be the most important. It was, after all, something their customers could not live without. When much of Provence was unified in 1246 by Charles of Anjou, the youngest brother of king Louis IX of France, the region’s salt came to be more rigorously and systematically monopolised, with Charles taxing it within his own lands and demanding extortionate prices of many of his neighbours.

By the 1260s, Charles had so extensively exploited Provence’s production of salt that it alone accounted for almost as much revenue as all his other sources of income combined. Salt thus provided the war chest for him to project power into the Mediterranean: he conquered the kingdom of Sicily, including all of southern Italy; conquered much of Tuscany, which he effectively exchanged for the principality of Achaea in Greece; twice sent troops into central Italy to secure the elections of friendly Popes, John XXI and Martin IV; conquered Albania; purchased the sliver of what remained of the kingdom of Jerusalem; and joined his brother on crusades against Egypt and Tunis.¹¹ Few have heard of it today, but Charles of Anjou created an empire based on salt.

What do you think of my newfound mapmaking skills?

On the other side of Italy the Republic of Venice — a city situated amidst a salty lagoon — used salt to exert its control over many of the territories further inland into north-eastern Italy. While Charles of Anjou was projecting his power into the Mediterranean, Venice continually went to war in the thirteenth and fourteenth centuries to force these territories, eventually including cities like Verona, Vicenza, Padua, and Brescia, as well as much of modern-day Slovenia and Croatia, to buy their salt from it and it alone. At one point it even forced its salt on Milan.¹² When Venice’s own salt lagoon eventually proved insufficient to meet the demand that it had enforced, the Republic then looked further afield for its salt supplies, offering high prices and substantial subsidies for ships importing it from across the Mediterranean — from North Africa, Ibiza, Sardinia, and especially the salt lakes of Cyprus, which became part of its empire — to make itself the region’s entrepôt for salt, while charging even higher prices to the populations it ruled.

The profits from Venice’s salt gabelle were fundamental to its military and financial might. By the end of the fifteenth century the proceeds accounted for about 15% of the Republic’s overall revenue. This does not sound like much, but the figure masks its true importance: the income from salt was more or less the only revenue that accrued directly to Venice itself, rather than being collected and immediately re-spent in the territories that the Republic ruled over. Sourcing and selling the salt, as well as enforcing the monopoly, was sub-contracted out to wealthy merchants — a process called tax farming — who in return for management of the monopoly paid the Republic a substantial but regular annual fee. Farming out the salt monopoly gave its revenue greater predictability, and for a few brief periods gave the Republic a kind of superpower that most other medieval states lacked: the ability to pay its debts. The revenues from Venice’s salt monopoly was often directed to paying the interest on loans, though fighting Genoa and Milan, followed by the rise of the Ottomans and France, eventually stretched it too far, costing the Republic its creditworthiness.¹³

The most infamous gabelle, however, was that of France. This seemingly owed its origins to a 1315 regulatory initiative in response to a salt shortage, to punish merchants who were allegedly hoarding the commodity. The king thus created a small bureaucracy of regulators with the powers to confiscate, stockpile, and then sell on the supposed hoarders’ salt. In the 1340s, however, the kingdom was plunged into crisis when Edward III of England invaded to claim the French crown as his own. Under intense pressure for cash, the salt regulation mutated, first with a 1342 gabelle levied on all salt exported, and in 1343 with the regulators’ powers of confiscation used to take the entire domestic salt supply into the crown’s hands as well. The salt was stockpiled into granaries by the officials and sold onto the French population at inflated prices. Following English victories and the need to stamp out marauding mercenaries and peasant revolts, the prices charged under the French gabelle became increasingly exorbitant.¹⁴ Yet salt was the thread by which the French king Charles V held onto his crown, helping him eventually claw some of his kingdom back from English occupation in the 1360s and 70s.

The French gabelle became exceptionally oppressive to the people who lived in the king’s core domains — a broad northern chunk of what is today France, centred on Paris, which came to be known as the pays de grande gabelle, or lands of the greater gabelle. Foreign visitors even remarked on the blandness of French bread there, devoid of salt.¹⁵ In this region the population were eventually made to purchase a minimum amount of salt for both themselves and their livestock from the granaries, making the gabelle’s resemblance to a poll tax all the more obvious. The major exception was a salt-producing region of Normandy, where a quarter of all the salt that was boiled was taxed at source rather than via the granaries — the quart-bouillon, which perhaps best translates as the quarter boilage.

Only as new regions came under direct control of the French king, clawed back from either English occupation or removed from the control of semi-independent nobles, was the gabelle extended to the rest of modern-day France. But this usually involved preferential treatment to ease the transition and keep them pacified. Much of southern France thus came to be the pays de petite gabelle, or lands of the lesser gabelle, being subjected to much lower salt taxes when they came under the French king’s rule. And some regions were exempted entirely, including some of the main salt-producing regions on the Bay of Biscay off France’s western coast. The duchy of Brittany, for example, didn’t have to pay the tax at all.

France’s gabelle regions during the Wars of Religion, shown more or less (my hand wasn’t always steady) with its 1559-1600 borders. The enclave in the south-east is the county of Venaissin around Avignon, ruled by the Pope. The exclave in the north-east is the former bishopric of Metz, controlled by France since the 1552 treaty of Chambord.

In the 1540s the king attempted to make the system fairer and more uniform by lowering the tax on salt in the lands of the greater gabelle, but raising it in the lesser-taxed salt-producing regions of southwestern France on the Bay of Biscay. Those regions, however, erupted into revolt, with Bordeaux even waving the English flag of St George as a symbol of its resistance.¹⁶ Eventually forced into submission, the regions agreed to pay the king huge one-off sums to free themselves of the gabelle forever, their representatives grovelling before the king with nooses symbolically worn around their necks.¹⁷ As a result of this buy-off, the regions came to be known as the pays rédimés, or redeemed lands. But salt seems to have become a lingering source of resentment and suspicion against royal centralisation, with some of these redeemed regions becoming hot-beds of French Protestantism.

When in the 1560s France descended into decades of periodic religious strife — its Wars of Religion — the contest was ultimately decided by fighting over control of the salt. Although the Catholic heartlands were those with the most onerous gabelle, where the consumption of salt was most heavily taxed, the Protestant rebels, called Huguenots, soon realised the value of controlling where that salt was being made. The two initial rounds of hostilities ended inconclusively, with both sides lacking the financial means for a protracted war. But when violence erupted for a third time in 1568, the Huguenots immediately rushed for control of the salt-producing western regions along the Bay of Biscay. Adopting the port of La Rochelle as their stronghold, they sold the next few months’ worth of the region’s salt production to the English for up-front cash and munitions.¹⁸

Using these salt-backed war loans turned out to be a winning strategy, with the Huguenots eventually forcing some concessions from the king despite a spate of battle losses — a strategy they repeated every time violence flared up again. Following the St Bartholomew’s Day Massacre of Huguenots in Paris, when in 1573 La Rochelle was besieged by the king’s Catholic forces, the Huguenots again sold the Bay’s salt to English merchants, helping them to resist wave upon wave of assault from a force at least five times their size, with the king losing between a third and a half of his army before he gave up and sued for a truce.¹⁹

And the Huguenots did it again in 1575 when that truce broke down.²⁰ This time around they also captured the salt marshes on the Mediterranean, particularly at Aigues-Mortes. The move gave them even more salt to sell, this time to the merchants of Genoa, and allowed them to hold the entirety of south-eastern France hostage for its salt supply as well, denying the king a major source of revenue from the gabelle.²¹ The cash the Huguenots raised from the Aigues-Mortes salt allowed them to hire a force of German mercenaries who would prove decisive in the war. The king was forced to terms that were extremely favourable to the Huguenots — so favourable, in fact, that many French Catholics were radicalised, resulting in a widespread Catholic uprising that yet again plunged the country into conflict.

But in 1577 the Huguenots were on the verge of disaster, largely because they had lost the salt: the defection of an important leader in the south lost them the Mediterranean salt at Aigues-Mortes, and then they lost the town of Brouage, not far from La Rochelle, where three years’ worth of Bay salt had been stockpiled for sale to the English and Italians. The surrender of Brouage, just days before the arrival of reinforcements, was unpardonable to the Huguenot cause. The surrendered garrison, upon reaching La Rochelle, was reportedly punished using the ancient Roman method of decimation: one in ten of them, chosen at random, were executed. But the punishment was in vain. Having lost the salt, this time it was the Huguenots who were forced to the negotiating table.²²

When religious strife erupted yet again in the 1580s, it was the Huguenot commander whose western power base gave the best access to the Bay of Biscay’s salt production — Henri of Navarre — who was able to fight his way, despite being outnumbered by his enemies, to become king Henri IV of France. Control of the salt ultimately meant control of France.

France may have been somewhat unusual, however, because of its geography. It had salt-producing areas on each of its coasts, but had an extensive interior with hardly any inland salt sources at all. Only in the 1670s, with the conquest of many of the lands to France’s east — Lorraine, Alsace, and the Free County of Burgundy — did it acquire a number of significant inland salt sources, and even then these were far from the main waterways running through the interior. Those waterways were crucial because a product as bulky as salt was otherwise exorbitantly expensive to transport overland. Thus, much of the population of France, along with the revenues of its state, could essentially be held hostage by whoever could control its salt-producing coasts and block the mouths of its major rivers — a fact appreciated by both its leaders and even its enemies.

In the 1620s, the French chief minister Cardinal Richelieu dreamt up an elegant solution to France’s salt-given predicament: to build a powerful navy, permanently remove La Rochelle’s defences, and extend the gabelle to all of the exempted or redeemed lands. The navy would help conquer La Rochelle, the defeat of the town would quash opposition to the gabelle, and extending the gabelle would help pay for both the navy and capturing the town.²³

In the event, however, the English intervened, seemingly sensing the looming threat of a rival naval power: in 1627 they pre-emptively attacked the island of Ré, just off the coast of La Rochelle, hoping also to take the nearby island of Oléron, just off Brouage — both islands, if taken, would be perfectly placed to strangle France’s salt supplies, diminish its gabelle revenue, and permanently embolden Huguenot rebels. If the salt could be seized, the English hoped, the expedition might even pay for itself.²⁴

The English invasion was an abject failure; La Rochelle fell to Richelieu’s forces; and the French navy expanded. The scene was set for the long reign of Louis XIV a generation later, whose epithet the “Sun King” would be fitting, his absolutist rule quite literally secured by the evaporation of seawater by the sun. But Richelieu’s plan did not quite come together fully: he never managed to extend the gabelle.

Richelieu at the blockade of La Rochelle in 1628, as envisaged in 1881 by Henri Motte

France’s geography perhaps made it a kingdom uniquely prone to being controlled in this way.

Compare with Spain, which not only had an extensive sunny sea coast, but plenty of inland salt sources as well. Spanish rulers did try to control and tax the production of salt, but the sheer number of potential salt sources made it difficult to enforce. Salt accounted for only about 6% of the crown of Castile’s revenue in the 1290s, and this figure was its peak. Despite repeated attempts to extract more, by the 1490s this had fallen to only about 3% of revenue and continued to fall.²⁵ In 1564 the crown even seized the salt sources not already under its control, compulsorily “purchasing” them from various nobles, religious orders and towns, many of which were never actually paid in full, and imposed a French-style system of salt granaries that most people had to buy from.²⁶ But even this drastic measure served only to restore salt’s importance to about 3% of revenue. There were simply too many potential sources of salt to be able to extract more, not only from the other Iberian realms like Navarre, Aragon and Portugal, but even from within Castile itself because of regional exemptions for places like the Basque coastal provinces. Smuggling and evasion were simply too rife to be able to extract more.²⁷

Much the same problems beset the kingdom of Naples, which encompassed the island of Sicily and the whole southern Italian peninsula. Although it had no major inland sources, the country was practically made of sunny coast, at about 38.5 metres of coast per square kilometre of landmass compared to about 10 or so for Iberia or France. When Naples was ruled by Charles of Anjou, the archetypal salt monopolist, salt’s percentage contribution to the kingdom’s revenue in 1278 was only in the single digits.²⁸ And in the 1440s, when the king of Naples required every household in the country to pay a certain amount for its salt, the revenues seem to have been disappointing.²⁹ The costs of policing such a long sunny coastline were simply too great to yield much profit for the crown. (Even into the twentieth century, the Italian coast was said to be “most rigidly guarded by tens of thousands of coastguards and police to prevent any person whatsoever taking a cupful of water out of the sea”.)

At the other extreme, however, states with little or no coastline at all found it very easy to raise revenue from salt. For the landlocked duchy of Lorraine, the sixteenth and seventeenth centuries exports from its inland salt springs typically accounted for between half and two thirds of the state’s revenue.³⁰ This even applied to landlocked states that did not actually produce any salt themselves. The dukes of the largely mountainous, Alpine region of Piedmont-Savoy imported almost all their salt via a tiny foothold of coast at the port of Nice — imports that they could control with relative ease, while clamping down on competing sources. There were only so many rivers and mountain passes through which to smuggle. As a result, despite producing no salt of their own, the dukes of Piedmont-Savoy’s chief source of revenue was a gabelle levied on their own population’s salt consumption. In the 1560s a proposed increase in the salt price was even commuted into an actual poll tax.³¹

Indeed, there is something unusual about the landlocked areas of much central Europe, which may help explain why the Holy Roman Empire had so many tiny sovereign states: it had a great many inland salt sources. I’ve not had a chance to look into it carefully just yet, but it’s striking how almost all the major players in the region — Austria, Bavaria, Saxony, the Palatinate of the Rhine, Lüneburg, Lorraine, Burgundy, and Brandenburg — each controlled salt sources of their own during their periods of greatest influence. Many bizarrely small sovereign states, too, like the Provostry of Berchtesgaden, seem to have maintained themselves by exporting salt. And the unusually wide dispersion of salt supply in inland Germany may also have helped maintain the sovereignty of tiny countries that didn’t produce any salt of their own — the Swiss cantons, for example, taxed consumption of salt that had to be imported, much like Piedmont-Savoy did, but their position meant they could often play the salt-selling Bavarians, Austrians, and French off against one another.

The geography of salt was thus a big deal, and may even have defined the contours of many early modern states. But there were social factors too. Although the demand for salt was highly inelastic, there were limits to how much oppression people would tolerate. There was a point at which they resorted to violence. France saw this every time it attempted to extend the gabelle into exempted regions — with the southwestern revolts that needed redeeming in the 1540s, as we’ve seen, as well as with a revolt in Normandy in 1639, and in Roussillon in the 1660s. In Spain, a 1632 attempt to regularise and extend the gabelle had to be dropped after widespread opposition. And in Piedmont-Savoy, an attempt in 1680 to extend the gabelle to the region of Mondovì, which had been exempted when it originally joined the duchy, sparked a violent revolt that took almost twenty years to finally stamp out. Most dramatically of all, in Russia the salt gabelle was such a major source of discontentment that the government became too afraid to raise salt prices. From a peak of about 15% of revenue being raised by the gabelle in the 1750s, by the 1790s salt prices were being held so artificially low that the gabelle’s revenue had gone negative — rather than taxing salt, the government found itself effectively subsidising it.³²

Rise of the Rest

You might be starting to get an appreciation now for just how many places taxed salt — I’ve mentioned France, Spain, Poland, Russia, and various states of Germany and Italy. It was also a big earner for states in the Middle East, India, and China, with many of the same geographical factors applying to the success of salt taxes in exactly the same way. But it was not the empires of the sun, or even the wood-fuelled brine springs of inland states, that would reap the biggest rewards from salt.

It was, strangely, instead in the chilly, damp north-west of Europe, that the greatest gains were to be had. More on that in Part II.

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1. Edward Hughes, Studies in Administration and Finance 1558 - 1825, with Special Reference to the History of Salt Taxation in England (Manchester University Press, 1934), p.2

2. Anon., Theological and philosophical treatise of the nature and goodness of salt (1612), p.12

3. Blaise de Vigenère (trans. Edward Stephens), A Discovrse of Fire and Salt, discovering many secret mysteries, as well philosophical, as theological (1649), p.161

4. A relation, concerning the Sal-Gemme-Mines in Poland, Philosophical Transactions of the Royal Society of London 5, 61 (July 1670), p.2001

5. Quoted in H. R. C. Wright, ‘Reforms in the Bengal Salt Monopoly, 1786-95’, Studies in Romanticism 1, no. 3 (1962), p.151

6. Gervase Markam, Markhams farwell to husbandry or, The inriching of all sorts of barren and sterill grounds in our kingdome (1620), p.22

7. e.g. John Collins, Salt and fishery, a discourse thereof (1682), pp.23-4, 28

8. e.g. Adolphus Speed, Adam out of Eden (1658), pp.105, 118, 136-7

9. Roy Moxham, ‘Salt Starvation in British India: Consequences of High Salt Taxation in Bengal Presidency, 1765 to 1878’, Economic and Political Weekly 36, no. 25 (2001): p.2270–74.

10. George O’Brien, The Economic History of Ireland in the Seventeenth Century (Maunsel and Company Limited, 1919), p.244, which has the transcription of Wentworth’s proposal

11. J. de Romefort, ‘L’ancêtre de La Gabelle: Le Monopole Du Sel de Charles d’Anjou’, Revue Historique de Droit Français et Étranger (1922-) 31 (1954): pp.263–69.

12. Patrizia Mainoni, ‘The Economy of Renaissance Milan’, in A Companion to Late Medieval and Early Modern Milan: The Distinctive Features of an Italian State (BRILL, 2014), p.123

13. Jean-Claude Hocquet, ‘Venice’, in The Rise of the Fiscal State in Europe c.1200–1815, ed. Richard Bonney (Oxford University Press, 1999), pp.381–415

14. Jean-Claude Hocquet, ‘L’impot Du Sel et l’etat’, in Le Roi, Le Marchand et Le Sel: Actes de La Table Ronde, L’Impôt Du Sel En Europe XIIIe–XVIIIe Siècle, ed. Jean-Claude Hocquet (Presses de l’Universitaires de Lille, 1987), pp.31-7

15. Ibid., p.33

16. Neil Murphy, ‘Henry VIII’s First Invasion of France: The Gascon Expedition of 1512’, The English Historical Review 130, no. 542 (2015), pp.55-6

17. 'Spain: June 1543, 6-10', in Calendar of State Papers, Spain, Volume 6 Part 2, 1542-1543, ed. Pascual de Gayangos (London, 1895), pp. 363-385, no.151

18. Edward Hughes, ‘The English Monopoly of Salt in the Years 1563-71’, The English Historical Review 40, no. 159 (1925): pp.334–50.

19. "Cecil Papers: December 1597, 1-15," in Calendar of the Cecil Papers in Hatfield House: Volume 7, 1597, ed. R A Roberts (London: Her Majesty's Stationery Office, 1899), 500-517: 1 December 1597 letter by Sir Henry Killigrew and Robert Beale to Sir Robert Cecil, noting La Rochelle’s failure to repay a 1573 salt loan to some London merchants. For the relative size of forces at the siege, see Kevin C. Robbins, City on the Ocean Sea: La Rochelle, 1530-1650: Urban Society, Religion, and Politics on the French Atlantic Frontier (BRILL, 2021), p.211, note 49

20. "Rome: February 1575," in Calendar of State Papers Relating To English Affairs in the Vatican Archives, Volume 2, 1572-1578, ed. J M Rigg (London: His Majesty's Stationery Office, 1926), pp.196-197.

21. "Cecil Papers: May 1575," in Calendar of the Cecil Papers in Hatfield House: Volume 2, 1572-1582, (London: Her Majesty's Stationery Office, 1888), pp.96-99: see 29 May 1575 letter by Valentine Dale to William Cecil that “Aiguemortes and Beaucaire … are towns not to be parted with without good consideration, for by them they have the revenue of the salt in that country a good port in the Levant Sea [Mediterranean], and also a passage upon the river Rhone, a means of conveying the salt up into the country, and therefore the king strikes hard upon these towns”

22. The Huguenot leader, the future king Henri IV, sent word to the English of his victory at Brouage, in particular singling out the salt he had captured there. 'Elizabeth: August 1577, 21-25', in Calendar of State Papers Foreign: Elizabeth, Volume 12, 1577-78, ed. Arthur John Butler (London, 1901), pp. 89-115. See also: "Venice: August 1577," in Calendar of State Papers Relating To English Affairs in the Archives of Venice, Volume 7, 1558-1580, ed. Rawdon Brown and G Cavendish Bentinck (London: Her Majesty's Stationery Office, 1890), pp.558-564, no.683; Mark Greengrass, Governing Passions: Peace and Reform in the French Kingdom, 1576-1585 (Oxford University Press, 2007), pp.123-153

23. See Richelieu’s memoirs

24. See reports of 13 and 27 August by the Venetian ambassador in England, in 'Venice: August 1627, 11-19', in Calendar of State Papers Relating To English Affairs in the Archives of Venice, Volume 20, 1626-1628, (London, 1914) pp. 319-348

25. Pablo Ortego Rico and Íñigo Mugueta Moreno, ‘Kingdoms of Castile and Navarre’, in The Routledge Handbook of Public Taxation in Medieval Europe, ed. Denis Menjot et al. (Routledge, 2022), pp.120-154

26. Claudia Mineo, ‘Law, Litigation, and Power: The Struggle over Municipal Privileges in Sixteenth-Century Castile’ (Ph.D. thesis, University of California, Los Angeles, 2006), pp.55-6, 268

27. Rosario Porres Marijuán, ‘La Política Fiscal de Felipe II En Alava: El Estanco de La Sal de 1564’, in Poder, Pensamiento y Cultura En El Antiguo Regimen: Actas de La 1a Semana de Estudios Historicos ‘Noble Villa de Portgalete’ (Eusko Ikaskuntza, 2002), pp.47–78.

28. It was about 10% of indirect tax revenue, so must have been well under that proportion once direct taxes and other revenues were taken into account.

29. Mark Aloisio, ‘Salt and Royal Finance in the Kingdom of Naples under Alfonso the Magnanimous’, Medioevo Adriatico 3 (January 2010), pp.9–28.

30. E. William Monter, A Bewitched Duchy: Lorraine and Its Dukes, 1477-1736 (Librairie Droz, 2007), pp.43, 49, 119, 161

31. Matthew Vester, ‘Territorial Politics and Early Modern “Fiscal Policy”: Taxation in Savoy, 1559-1580’, Viator 32 (January 2001), pp.279–302

32. Richard Hellie, ‘Russia, 1200–1815’, in The Rise of the Fiscal State in Europe c.1200–1815, ed. Richard Bonney (Oxford University Press, 1999), pp.480–505

Age of Invention: More the Merrier

Today I’m making good on a promise. A few months ago I said that I would start practising what I preach, and “begin to upload to somewhere freely accessible the transcripts and notes that I use or cite in the work that I publish”. Well, today I begin, kicking off with my transcripts and notes from the travel diaries of Samuel More — secretary for almost thirty years to the Society for the Encouragement of Arts, Manufactures and Commerce, widely considered by his contemporaries to have been one of the leading experts on the inventions and industries of the late eighteenth century.

I’ve cited these diaries a few times this year: for More’s vivid descriptions of iron foundries and early railways, for his romantic impressions of the Staffordshire Potteries, and for his first-hand account of the mountain of the Welsh copper king. It has informed many of my other pieces this year too. And having helped to publicise them, even just the snippets I’d shared started to generate some new knowledge among specialists: new technical details about some 1760s Cornish Newcomen engines, for example, and about 1770s railway construction. It’s especially rich in details about ironmaking, because More was best friends with John “Iron Mad” Wilkinson. But the only way to have gone and checked the source for yourself would have been to either visit the British Library to view the manuscript yourself, or write to me to ask for more extracts or photographs.

Until now, that is, because I have just made my full transcripts, summaries, and notes from the diaries — over 100,000 words of everything and anything in them relating to industry, manufactures, inventions, agriculture, economic conditions, and infrastructure, with a great deal more besides — available for all to freely view online. You can read it here. My Christmas present, if you will, to all researchers.

I’m aiming to publish one last piece this year, but in the meantime if you’re stuck for reading while digesting some festive treats, here are what I personally consider my best pieces this year:

• The interactive history of the steam engine

• On the risks and responsibilities of writing history for the public (with some reflections on a still-unresolved academic controversy)

• On the eighteenth-century mania for improving animals

• On the rise of London and its lost county feasts

• On how Boulton & Watt did not sell steam engines, but power

And as a Christmas bonus, here’s a piece from a few years ago that used to be behind a paywall, but which I was recently reminded of and I’ve now made free for all to read:

• On the most surprising would-be colonial powers

If you’d like to support my work, you can upgrade to a paid subscription here:

Age of Invention: The Interactive History of the Steam Engine

You’re reading Age of Invention, my newsletter on the causes of the British Industrial Revolution and the history of innovation. This edition went out to over 26,000 subscribers. To support my work, you can upgrade your subscription here:

I’m excited to announce something I’ve been quietly working on for a few months now behind the scenes. Some of you may be familiar with the explorable interactive articles of Bartosz Ciechanowski. They are so clearly written and so cleverly explorable, that they give an intuitive grasp of how many very complicated technologies work. My favourite is his article on mechanical watches. Be warned: if you’ve not seen these before, you’re about to lose a good few hours.

But his article on watches — which came out just as I was doing some research on the development of watches, and which proved an invaluable reference work — got me thinking about how great it would be to have something similar not just for how current technologies function, but to show how they changed over time. Wouldn’t it be great, I dreamed, to have a similarly intuitive way to explore and appreciate the process of improvement. And to correct lots of misapprehensions about the development of various technologies along the way.

As it turned out, my fellow inventions history fanatic Jason Crawford, who runs the non-profit The Roots of Progress, had been thinking along the same lines. (Drumroll starts softly.) So with the help of the Matt Brown we’ve been able to realise what is hopefully just the first small step of our vision. (Drumroll intensifies.) Based on my recent work re-writing the standard pre-history of the steam engine (drumroll crescendoes), allow me to present:

(Cue trumpets!)

The interactive, animated, **Origins of the Steam Engine**

Alongside contemporary illustrations of the many devices, you can play around with the animated models, dragging them to see them from different angles. It introduces what are so far the only interactive and animated models yet made of a great many devices — from Philo of Byzantium’s 3rd Century BC experiments, to Salomon de Caus’s 1610s solar-activated and self-replenishing fountains and musical instruments, and the 1606 steam engine of the Spanish engineer Jerónimo de Ayanz y Beaumont:

It also contains the first depictions of the 1630s and 40s devices of Kaspar Kalthoff and William Petty. These are the experiments I discovered about a year ago, which I hope will now be given a place in the canon of the history of the steam engine. (You can read my discussion of the evidence I’d stumbled across about them here.)

And it contains what ended up becoming a brief obsession on my part: the first depiction of how Cornelis Drebbel’s “perpetual motion” device at Eltham Palace must have worked. Although there have been a few attempts with modern experiments to show how some parts functioned, this is the first attempt at showing it all together, including how the internal clockwork was driven and periodically rewound.

The strands of development culminate in the steam engine patented by Thomas Savery in 1698 — a device that had hardly ever been depicted accurately, and which has never before been shown interactively. The much more famous Newcomen engine, revealed to the world just a few years later in the 1710s had — until now — always stolen the limelight.

The plan is to continue to develop the interactive articles. No doubt there will be a few errors that need correcting. There will also be some devices to add — a few are alluded to in the text, but not yet illustrated. I wouldn’t be surprised if in the near future someone were to discover yet more forgotten devices like Kalthoff’s and Petty’s. But I’d also like to trace the development of the steam engine even further, with a follow-up instalment taking us from the devices of Denis Papin and Thomas Newcomen through to James Watt and the high-pressure engines of Richard Trevithick, tracing all the lesser-known improvements and devices inbetween. And to start creating these for other technologies too.

So long as Jason and I can continue to find funds for our animator’s time and talent, then this is just the beginning.

But enough of my hopes and dreams and behind-the-scenes commentary. Go and explore the interactive diagrams for yourselves!

Age of Invention: How to be a Public Historian

Writing for a public audience is a double-edged sword. It’s all very well to want to put your work out there and reach as wide an audience as possible – and even if it’s not something you really yearn for, it’s still heavily encouraged and incentivised throughout academia. But it comes with significant risks, and those only grow and multiply as you reach a wider and wider audience.

Most people have no conception of what it might be like to reach a truly massive audience. A few years ago the self-help guru Tim Ferriss wrote an eye-opening piece on what it’s like to be even only somewhat famous. There are certainly upsides. You might make new friends, be able to substantially aid the causes you’re passionate about, and perhaps even make some money. 

But as Ferriss notes, it’s a Faustian bargain. Just through sheer numbers alone, if your work reaches an audience the size of a city, or perhaps even a small country, then it will inevitably reach a lot of people who are simply mad, bad or sad. Even if you’ve said nothing that could reasonably be construed as controversial, you might receive threats and have insults hurled at you. You’ll receive all the more if you have. And even the most anodyne or obscure things you have said will reach people who want it to be either completely false or unquestionably true. All just because it will allow them to score some cheap point over some other people they loathe. The wider the audience your work reaches, the more this will happen.

Along with those risks, however, if you try to reach a wide public audience then you also have a responsibility – because the things you put out there will be used in ways you may never have anticipated and which you simply cannot control. To give a personal example, a few years ago I wrote a couple of pieces on whether the Ottoman Empire really banned the printing press, in which I raised the speculative possibility that what had been called a “ban” by European observers may actually have been an excuse used by Ottoman officials to block specifically foreign, Christian propaganda. Now, I took great pains to show exactly what scanty evidence I was drawing on to infer that story and signalled throughout that it was really very speculative. But I occasionally see it shared on social media by Turkish nationalists as definitive proof of what happened, and serving as ammunition against people they feel are insulting their heritage by merely saying that the Ottoman Empire had restricted the printing press. And that’s despite even opening the piece by noting how the politicisation of the history of the printing press in the Ottoman Empire – on all sides, no matter how well-meaning – has got in the way of actually working out the truth. (Hate-mail incoming in 3.. 2..)

Given the unpredictable ways in which historical work gets used and abused as it reaches a wider audience, it does however demand caution. If you make a speculative case, it should be very clearly labelled as speculative. And if you present speculation as fact, then the wider the audience this reaches, the more you can expect this to be called out. Because we all like to know what’s true. Given the way information is used or abused, for better or for worse, the one thing that unites the good actors and the bad is that they like to be dealing with information they’re confident is sound. 

One thing I’ve noticed as my own audience has grown – to over 26,000 people now, far in excess of what I ever expected when I started this newsletter just over four years ago – is that there is no surer way to provoke a reaction, ranging from the painfully polite correction right down to hostile name-calling, than to make an actual mistake, even if it’s entirely innocent. There seems to be a fairly universal human urge to correct what is incorrect, each in our own way, and bring our own expertise to bear, whether we notice a thesis-shattering counterproof or even just a mere spelling mistake. 

This is downright terrifying. Long-time readers might have noticed that nowadays I tend to publish much longer but also less frequent posts than I did some years ago. This is because as my audience has grown from the hundreds to the thousands and then to the tens of thousands, I feel a greater and greater sense of responsibility to not accidentally get something wrong. It’s embarrassing enough to tell a story that turns out to be wrong to a group of friends – we’ve all been there. But it’s excruciating when you’ve accidentally misinformed a group the size of a medium-sized town.

And yet, it’s also exciting. When you reach a large audience you inevitably also reach people who are better-informed or more specialised than you on a dizzying and even unpredictable range of topics – a large audience is also a wide audience. Even if I think I know a lot about early steam engines – and I think it’d be fair to say I know more than even the average historian of technology – with a wider audience it gets more and more likely that the things I write will come to the attention of people who know far more. It’s a simple, mathematical inevitability. 

It’s not just inevitable. It’s to be actively sought, because it makes us better. One of my favourite things about what I do is that I have come to the attention of people who possess a vast and specialised expertise on a wide range of topics – and who will not hesitate to correct me when I’m wrong. I can’t help but experience a little trepidation when I see certain names pop up in my inbox or on social media – like John Kanefsky when I happen to mention steam engines, John Styles when I write about textiles, or Judy Stephenson when I mention labour practices, to name just a few. When such names pop up, even if I haven’t actually got anything wrong, I know I’m still about to be schooled. And that my work is about to be improved as a result. Reaching a wider audience and actively seeking correction disciplines me to check the information I put out into the world, or at the very least to express my uncertainty where it’s appropriate, and it makes it more likely that any misinformation I’ve already inadvertently put out there gets cleaned up. 

The other day I got to meet another substack newsletter writer with an audience of a similar size to mine – the wonderfully curious Mike Sowden. One thing he did recently is ask his audience to leave a comment calling him an idiot, ideally explaining why – both a call for correction and a kind of icebreaking exercise so that, having already called him an idiot once, people will get in touch with him more often with their corrections in future. From what he tells me, it sounds like it’s been a roaring success, exposing him to the privilege, quite frankly, of his audience’s expertise. I’ll remind you again later, but when you’ve finished reading this to the end I’d like you to leave a comment: it may or may not be to correct something I’ve said here or elsewhere, but at the very least just call me an idiot. 

Principles of Proportionality

Now, Mike and I are clearly gluttons for punishment. And in general calling people idiots is unlikely to result in misinformation getting corrected by the people responsible for it. Even if it’s thoroughly deserved. It certainly is in Mike’s case. But the way we try to correct misinformation, intentional or otherwise, has to be proportional.

This brings me to a case I first wrote about in July, and which I returned to in August, when new evidence had come to light. You’ll have to forgive me for bringing it up for a third time, and I’d even resolved after the second time that that would be that. In the months that followed I’d avoided any further mention of the matter on social media, and I’d scrupulously avoided even “liking” any posts about it, as I knew that might propel it into people’s timelines again. I felt I had already acted proportionately in trying to correct some misinformation, and that taking it any further would be pushing it. So I’m hoping this will be the very last time I ever have to mention it in public ever again. You’ll see why.

The case involves a paper by Jenny Bulstrode published in June in the journal History & Technology. As a quick recap, it claimed the following: that the inventor Henry Cort had stolen his famous 1783 iron-rolling process from an ironworks called Reeder’s Pen in Jamaica, where it had been developed by 76 black metallurgists by passing bundled scrap iron through grooved sugar rollers. The paper then claimed that Henry Cort heard of the process via a cousin named John Cort who had been in Jamaica, and that Reeder’s mill was destroyed and its machines dismantled and taken to Portsmouth where Henry Cort could use them. It insinuated, though without saying so directly, that Cort may have used his connections in the Admiralty to achieve this destruction and theft (something that the author then claimed explicitly in the media, specifically on a podcast called The Context of White Supremacy).

It was very widely reported in the press – in The Guardian, Mirror, New Scientist, on NPR, and in heaps of local newspapers and more niche sites. On social media it went viral, with thousands of people reading and praising it. And I think it’s fair to assume that this attention was actively courted. Someone made the decision for the paper to be made open-access, and thus free for all to read rather than behind the usual academic journal paywall, and the paper was heavily promoted by the journal’s publisher Taylor & Francis as well as by the writer’s department of Science and Technology Studies at UCL. Within days there were local politicians calling for Cort’s name to be expunged from the names of streets and public buildings, and the Wikipedia entries associated with Cort and his innovations were heavily updated in light of its conclusions. After all, History & Technology, as a double-blind peer-reviewed journal, has all the hallmarks of a trustworthy source.

But as I said before, pursuing a larger and wider audience for one’s work is a double-edged sword, coming with significant risks and responsibilities. 

You can be sure that it’s going to reach a lot of people who will attempt to use your work for their own ends. There will be a great many people who will want it to be right, because it is a compelling illustration of the neglected historical achievements of black people and of the injustices of colonialism and slavery. Indeed the author herself indulged in this, portraying it in the media as important evidence of the need for reparations. But there will also be a great many people who want it to be wrong, perhaps because they wish to downplay historical injustices or the achievements of black people, or even just so that any criticism can show that the political activists they disagree with are more generally untrustworthy. “Woke gone mad”, etc.

Yet for these political arguments whether it’s actually true or not is really neither here nor there. It’s not as though we don’t already have countless cases of the injustices of colonialism and slavery or examples of the achievements of black people. It’s not as though showing someone was wrong about a single, hyper-specific case study does anything at all to invalidate much broader political arguments. It’d be enormously egotistical of historians to pretend otherwise, as though real justice can only be pursued or achieved because of their own research.

The philosopher Liam Kofi Bright skewered it all perfectly in a single tweet:

Huge debate going on among historians right now about whether some black metallurgists did something with rollers (?) that made steel more... steely... and then had that nicked by some Brit. The fate of equality rests on this, following matters closely.

Quite. And if you do think that the fate of equality hinges on whether a man who died 223 years ago copied and took credit for a very specific ironmaking technique that until a few months ago only a handful of nerds like me had ever even heard of, then I’d prescribe a complete political and current affairs detox. I’m qualified to prescribe this as a doctor with a real PhD, rather than a mere physician: throw away your smartphone, cancel your broadband, and keep yourself at least five miles distant from the nearest population centre for at least a year. The full works.

And apart from those who want you to be wrong or right, you’re also going to come to the attention of people who know a thing or two about the things you’ve discussed – those terrifying people with deep expertise, and even just the more generalist but informed idiots like me. I read the paper the day it was published, but I didn’t write anything about it until after a number of people began to either email me or ask me on social media about it. As I write regularly about inventors of the Industrial Revolution, some people naturally looked to me for my relatively informed opinion.

And I considered the narrative about Henry Cort to be wholly unsubstantiated, for the reasons I set out back then. I judged it to be misinformation, and misinformation that was spreading at a rapid rate. It was already well on its way to solidifying into a widely accepted fact. Now, calling it misinformation is not to say that it is disinformation, which is when an author purposefully misinforms – it is impossible for me to say, and I’m not even sure it really matters.

I left open the possibility that there was evidence the author had read but then simply failed to cite properly. I constantly used the phrase “no evidence presented”. That is not the same as “no evidence”. Misremembering a citation or even just accidentally deleting one in the process of editing and re-editing a piece is all too easy, and I’m not embarrassed to say that I’ve done it a few times myself. If I were shown that there was evidence after all, it would then have been on me to update and perhaps even withdraw my critique — it would have been embarrassing not to, and with the public so interested in the matter I’d have had nowhere to hide! They’d never have let me forget about it. But until shown otherwise, I judged it to be misinformation. 

And I think we should try to correct misinformation when we see it, regardless of its source or whether it was produced with the best or the worst of intentions. It behoves us when we have the expertise and have already done the work to verify – or in other words, when we have the means. And it especially behoves us to correct misinformation when it looks like it’s becoming widespread. If someone’s completely wrong paper is likely only going to be read by them and their Mum (that’s British for Mom), then it may not be worth going to the trouble of correcting it. If it’s been seen by hundreds, thousands, or even millions of people, however, and is being taken seriously, then that’s another matter.

Which brings me back to proportionality, which I think is determined by two factors: 1) the size of the audience it has already reached, and 2) the ease with which the most influential source of the misinformation can be changed.

Had Bulstrode’s theory been contained in just a tweet or a blogpost, I’d probably have just written to her directly and privately. I might not even have bothered to do anything at all – tweets and blogposts are not generally the stuff of which widely accepted facts are made, even if they go viral. And they’re easily deleted or changed. I quietly inform people of errors all the time, and people do the same for me – it’s like telling someone they have spinach stuck in their teeth. It may feel awkward to do, but you’re really doing them a favour. 

This, however, was another matter entirely. Not only had the information already reached a vast number of people, but published journal articles – particularly in history – are almost never corrected or changed. If they are, it takes months if not years, by which time the genie cannot be put back in the bottle. Under those circumstances I think it’s best to publish a critique pointing out the misinformation so that it can also reach as wide an audience as possible, though the nature of these things is always that the rebuttal will only reach a small fraction of those whom it had already misinformed. My blog will never be able to outdo the sheer reach of The Guardian, nor will it command the authority of a peer-reviewed journal. If anything, to be truly proportionate I perhaps ought to have done even more.

Just look at the vocal reaction of medieval and Tudor historians to the release of a book and Channel 4 documentary by Philippa Langley, the researcher who first came to prominence for her role in the discovery of the remains of Richard III under a car park in Leicester. This time, she’s back in the news to present the evidence that Richard III did not quietly murder his nephews in the Tower of London, but that the two figures we’re used to thinking of as mere pretenders, Lambert Simnel and Perkin Warbeck, were in fact the real princes. The theory, often presented with a great deal of certainty, has achieved a huge level of publicity and is backed by a bemusingly active group of people who want it to be right – Richard III was Yorkshire-raised, and many English northerners bloody love the north and won’t hear a bad word against the only king who may plausibly be called one of their own. 

So other historians concerned about misinformation express their concerns publicly. They do not, and should not, merely write privately to Langley. Suppose she were to be convinced she’s wrong? What’s she supposed to do, somehow track down everyone who’s read her books and tell them to chuck it in the bin? Tell people to unwatch the documentary? No. The genie is out of the bottle. And so we instead have a lively and (largely) healthy debate played out in public – just as it should be. When misinformation is widespread, you counter it by spreading the information that is correct.

But the other reason I felt I had done enough is that I was not the only expert to have noticed the problems with Bulstrode’s paper. Back in August I shared a working paper by someone – Oliver Jelf, then completing his dissertation for a research masters from Buckingham University, and otherwise a graphic designer – who had got in touch with me after digging into it further. Jelf did not just read the paper and take everything at face value, but went to double-check some of the key sources it had used, which he also transcribed for anyone to read and judge for themselves. He showed that some of the claims in the paper were not supported by the sources that had been cited, and even that many could not be supported at all. And what he also did was submit his response to the journal that had published the original paper, asking if they would publish it as a response.

I also then learned of yet more critics, of whom I had been completely unaware. I mentioned the names of experts that I cannot help but regard with trepidation. Well, the one for iron is Peter King. There cannot be a single person alive today on the entire planet who knows as much about eighteenth-century ironmaking as him. He has meticulously researched and published on the history of ironmaking for decades, and just a few years ago finished compiling the monumental A Gazetteer of the British Iron Industry, 1490-1815. And there’s Richard Williams, a trained ferrous metallurgist – his doctorate was on the thermodynamics of iron-carbon interactions – who has over the past decade been correcting metallurgical misunderstandings that had crept into the history of eighteenth-century ironmaking.

Within days of the initial press attention for the paper, King and Williams were among a group of experts on the history of metallurgy who were starting to be asked questions about Bulstrode’s paper – including by various industrial heritage sites about whether they needed to update their displays to reflect the paper’s new narrative about Cort. And the information requests kept coming. But, like me, they noticed big gaps in the evidence – along with a great deal more errors, coming from their position of specialised expertise in the practice and history of iron metallurgy. These were the sort of errors that Jelf and I were far too inexpert to have noticed. 

King and Williams took the “proper” channels. Their group drew up a brief summary of the paper’s problems and contacted the various newspapers that had covered the matter to issue corrections. They were completely ignored, and don’t seem to have been mentioned even once in any of the press coverage that began to appear in The Telegraph or The Times. They also contacted Bulstrode’s department and the publishers asking them to take down their promotion of the paper, and were again seemingly brushed off. And, of course, they contacted the journal’s editors.

Academia’s natural process of self-correction now seemed to be grinding into gear. Rightly ignoring all the politicised huff and puff on social media or the press, with culture warriors on the one side crowing at how the criticisms Jelf and I had raised were some kind of victory over “woke gone mad”, and those on the other side impugning critics’ motives in questioning the paper at all, it seemed only a matter of time until the editors would decide whether to either publish Jelf’s rebuttal or more thoroughly examine the paper’s evidence and retract it. At most, there’d be a little more huff and puff before the culture warriors on both sides would forget all about their brief interest in 1780s grooved iron-rollers and move onto the next thing to fight over. That would be that. End of story. A barely visible unpicking of a single stitch in the ever-expanding and changing tapestry of what we know about our history. 

Bulstrode would probably be a little embarrassed, but it’s not like it automatically invalidates all her other work or the work that she may do in the future. It was only a single paper after all, even if it got a moment in the harsh and uncompromising glare of the public spotlight. Remember that it was more or less accidental that the paper ended up being subjected to so much detailed scrutiny, purely a product of how much attention it received. Yes, she actively pursued the public’s gaze, but I think it’s probably fair to say that like most people she might not have appreciated what that could mean. There’s plenty of absolute garbage that gets published in other papers, which is probably of significantly greater consequence. Some misinformation can quite literally cost lives; I somehow doubt that getting it wrong on the metallurgy of 1780s Jamaica is going to be quite so perilous. But the difference is that hardly anyone has even heard of most papers, let alone actually read them.

As for the journal editors who would decide whether to retract the article, it was they who read the initial draft and decided it was worth reviewing, who chose the peer-reviewers, who decided to publish based on the reviews, and who helped publicise it once it was published. In general, editors wield a stamp of considerable authority, conferring legitimacy on academic work. Because nobody has the time to follow-up on every single thing they read – life’s too short – we rely on editors and the peer-review process to tell us what we can trust, at least relatively. Editors thus bear an immense responsibility. Their overriding duty is to preserve the trustworthiness and integrity of the journal. This is not just a matter of publishing good work – shoddy stuff will always manage to slip through the net – but above all it’s about ensuring that any misinformation is addressed through corrections or even outright retraction. Even if it might take a while.

Given the weight of the responsibility that they must have felt, I fully trusted that the editors would find a way to correct or retract the paper that would save everyone as much face as possible and we’d all move on. That’s just the way the institutions of academia work, right? 

Apparently not.

A couple of weeks ago the editors of the journal, Amy Slaton and Tiago Saraiva, issued a public statement. It’s an extraordinary document, which you can read here. On the one hand, they do admit that there is “no direct reference in any source quoted by Bulstrode or in the archaeological record to grooved rollers used to work iron at John Reeder’s foundry”. They also issue a correction to show that, as Jelf had demonstrated, Cort’s cousin did not in fact go to Portsmouth and bring him the news of such an invention for him to then appropriate as his own. Fine. That’s something.

But they then proceed to systematically misrepresent or simply ignore the most important criticisms made by Jelf and me in public, and by King’s and Williams’s group more privately. Slaton and Saraiva instead come out in “unreserved support” for the article. Although Cort’s cousin never went to Portsmouth, their correction is to say that the news of the innovation must surely therefore have been brought to him by the other, completely random ship the author had originally mistaken it for!

Allow me to very briefly address just a single argument – by far the most crucial point that they left unaddressed. Although they openly admit there is no direct evidence, Slaton and Saraiva argue that Bulstrode made a reasonable inference that there was an innovation at Reeder’s Pen. Let’s set aside for a moment that they also say Bulstrode “demonstrates” it, and that the language of the paper has not been updated to show the extent to which this is speculative. The crux is whether she makes a reasonable inference when claiming that grooved rollers were used there to make bar iron from heated bundles of scrap.

If this inference is unreasonable, then the inferences on which the rest of the narrative rests are all completely irrelevant. If there’s no reason to suppose that grooved rollers were used to make bar iron from heated bundles of scrap at Reeder’s Pen, then it doesn’t matter why the ironworks were destroyed, or whether the machinery was taken on board naval ships to Portsmouth, or whether John Cort or some other random ship sailed to Portsmouth or not, or really any of the chain of events by which Henry Cort is supposed to have stolen the innovation. If there was no innovation there to begin with, then there was nothing for Henry Cort to even steal.

The editors, and Bulstrode herself, make the inference based on the following: that grooved sugar-cane rollers were being made at Reeder’s Pen, that the black workers there thought sugar and iron were in some sense related conceptually, that the ironworks was profitable, that it recycled scrap iron, and that the ironworks used rollers – a technology they admit had been used in ironmaking for centuries, though usually with flat rollers.

They seemingly consider this to be sufficient to “conclude” that the workers “who were so familiar with both sugar and iron production overlapped in their approaches to the two operations and passed bundles of scrap metal through grooved rollers”, thus inventing a grooved rolling technique for iron that Cort later patented in 1783.

This is already tenuous at best. But the editors were also made aware of a host of further problems: 

One is that there is actually no mention in the sources of any iron rollers, flat or grooved or otherwise, in use at Reeder’s Pen at all – as Jelf very clearly demonstrated. But Slaton and Saraiva just totally ignore this, repeatedly asserting that the sources show the foundry “used rollers to produce iron goods”. In doing so, they merely reproduce the misinformation we were trying to correct. It’s not like they even contest our reading of the sources or provide new evidence on this point. In fact, they seem to fully accept the accuracy of the source transcriptions that Jelf appended to his paper. After all, they corrected the factual error he’d pointed out about the ship and admit the lack of any mention of grooved iron rollers in use. So they’ve been extraordinarily careless.

Instead of any rollers, King and Williams noted that the evidence relating to Reeder’s Pen is perfectly consistent with it having consisted of a water-powered bellows, chafery and helve hammers, along with an air furnace – old and well-known technology which is all you’d require to process scrap iron.

The editors also ignore the countervailing circumstantial evidence Jelf raised, that at no point did Reeder, the owner of the ironworks, who later even had a patent related to sugar, make any mention whatsoever of any innovations when he was begging the government for restitution for his demolished works. Considering he had every incentive to over-claim for what he had lost, why is there no record of any novelty? If Cort had copied a technology invented by Reeder’s slaves or other workers, you’d think he’d have made a very big deal of this. Again, Slaton and Saraiva simply ignore this point.

So the circumstantial evidence we’re left with is this: there was an ironworks, it was profitable, it probably just used old, well-known iron technology – and we have absolutely no reason to believe otherwise. Oh, and there were sugar rollers.

This is where it gets even more tenuous, and where they misrepresent my arguments. Slaton and Saraiva note, as I had pointed out, that when you roll iron the rollers must be horizontal. They also note that sugar rollers were typically vertical, but that by the late eighteenth century they were sometimes horizontal – which from the way they write it, they make seem like a refutation of an argument, when it is actually explicitly what I said back in July. To very tediously quote myself: “Such [sugar] mills could have the rollers either vertical or horizontal (but they’re almost always shown vertically).” (One of the fun things about substack is that because this blog also gets sent out as an email, about 20,000 people can even go and see the original version, just in case you suspect that I made any edits after the fact. And yes, that exact quotation is there.)

But what they ignored is what is most important – and is precisely what I had said was most important. Sugar rollers and grooved iron rollers of the kind Cort made use of were just fundamentally different. Maybe the source of confusion is in the use of the word “roller”. Sugar rollers were really sugar-cane crushers – their grooves were cut along the length of the rolls, to grip and squeeze. Iron rolling, instead, involves running hot iron bars through the gaps in grooves that run around the circumference of the rolls. Rolling iron through these gaps does not crush, but sort of stretches and smooths the sides and edges of the heated metal – that is what made Cort’s rolling process useful at all, so that the bars it produced became welded without any cracks. 

So even supposing you did have specifically horizontal sugar rollers there – and there’s no evidence to suggest even that, other than wishing it were true – then it’s really a matter of simple physics. Pass a heated bundle of scrap iron through a rolling sugar-cane crusher, rather than something that will stretch and smooth the sides and edges of the heated metal, and you are almost certainly just going to break the machine. The idea that sugar crushers were used to invent anything even remotely similar to Cort’s rolling process is thus simply implausible – it doesn’t matter if the black workers at Reeder’s Pen conceived of sugar and iron as conceptually related in any way. It just wouldn’t get you to that technology.

Incredibly, even in misrepresenting my arguments Slaton and Saraiva manage to make a sloppy error, even if it’s not a significant one. In their pretended “gotcha” to point out that horizontal sugar-cane crushers had been in use in the Caribbean by the 1780s, their proof is that “the first patent for horizontally positioned grooved rollers for processing sugar cane was granted to George Smeaton in 1754”, for which they give three citations. Except that they can only have actually checked the first of these: had they bothered to double-check this information, which would have taken all but five minutes of googling, they’d have noticed that it’s actually the famous engineer John Smeaton, not a George, and that he had no patent of this kind. They’d have noticed that this was probably a garbled reference to when John Smeaton in 1754 made drawings for a Mr Grey of Jamaica of a breast-shot waterwheel to power a three-roll horizontal sugar-cane crusher. They’d have noticed that Smeaton never went to Jamaica, that these drawings are marked “not executed” – that is, not actually made – and that mills on this model began to be produced in numbers only after 1794, though a few had seemingly been in use in French-ruled Haiti.

Anyway. We so rarely get the privilege of finding a smoking gun. Usually, the best we have to deal with consists of the kinds of snippets here and there of circumstantial evidence, informed by our wider, contextual knowledge. Writing about history is a puzzle where we lack a great number of the pieces. But what we have here is not just the lack of a smoking gun. There isn’t a body, and there isn’t even any blood. There hasn’t been report of a loud bang, or really anything at all. There’s just a quiet, empty street to which someone has turned up before suddenly rushing to the other side of town and arresting a random person – Henry Cort.

To my amazement, in a true testament to the power of public history, a great many people had apparently carefully read Bulstrode’s paper, my critique, and even Jelf’s paper. Before I’d even had a chance to begin writing up any of this, the public actually noticed some of these glaring omissions and began to raise them in response to the editorial. (Here’s just one example, albeit behind a paywall, on a newsletter by a non-historian that is about seven times the size of mine.) When everything is conducted in the open, where the arguments can be read by everyone, the public becomes like the all-seeing eye of a deity – there is simply nowhere to hide, and they are not to be treated like fools. When I make mistakes, they do the same to me.

Now, many of the people who noticed the editorial’s omissions will, I’m sure, be among those who want the paper to be wrong. But even suppose you had ninety-nine people attacking you with pure, unhinged, loathsome bile, if there were even just a single reasonable person who came to you with a compelling, evidence-based critique, then you’d still have to take that one voice seriously. If I say something ludicrous like “steel and iron are always the same” and ninety-nine people merely call me an idiot without elaborating, I can’t just dismiss Richard Williams when he pops up terrifyingly in my inbox with dozens of carefully reasoned pages explaining how they’re actually rather different.

To add insult to injury, Slaton and Saraiva impugned the motives and credentials of all the paper’s critics, seemingly associating any criticism with the horrid online abuse that a paper so widely publicised inevitably attracted on social media. In the case of Jelf, they even say they were “unable to ascertain” his academic or institutional affiliations, despite the fact he had emailed them directly to submit his paper. So they actually corresponded with him but then simply never bothered to ask, deploying their position of authority to sow doubt. (To my disbelief, though to his great amusement, I’ve even seen it speculated online that I invented Oliver Jelf. I’m not entirely sure why I’d need to invent a pseudonym with such an implausible-sounding backstory, having already put my name to a critique of the paper. Why on earth would I myself actively reduce the authority of a critique that I believe to be sound?)

But what most outraged many members of the public was the way the editors concluded, despite having repeatedly admitted that there was no direct evidence for the article’s claims. I will quote the last paragraph in full: 

We by no means hold that ‘fiction’ is a meaningless category – dishonesty and fabrication in academic scholarship are ethically unacceptable. But we do believe that what counts as accountability to our historical subjects, our readers and our own communities is not singular or to be dictated prior to engaging in historical study. If we are to confront the anti-Blackness of EuroAmerican intellectual traditions, as those have been explicated over the last century by DuBois, Fanon, and scholars of the subsequent generations we must grasp that what is experienced by dominant actors in EuroAmerican cultures as ‘empiricism’ is deeply conditioned by the predicating logics of colonialism and racial capitalism. To do otherwise is to reinstate older forms of profoundly selective historicism that support white domination.

Overall, there is not a single worse strategy that the editors could have chosen if they wanted to protect the paper from further, hostile criticism. Not only did the conclusion immediately lead to charges that they were putting politics above evidence, but it also provoked headlines and outraged reactions in the press. 

None of this was necessary. Even if the editors had not wanted to retract or make sweeping corrections – though I still can’t see why not – they could have found a way to condemn the personal attacks on the author while then publishing one of the carefully assembled critiques that had been sent to them and allowing the author to then reply. Or they could have even gone further, going through the evidence-based critiques point-by-point, offering new sources where they were lacking, and defending or correcting each point. But they simply chose not to.

And that choice meant that they leaned on their authority, deploying the trust that we all have that the process is still working. The author’s department immediately issued a press release saying that she had been “fully vindicated” and that all the fuss on social media and the press had been the result of “a hostile and organised response from a small number of people”. Much, much more seriously, last week the council of the British Society for the History of Science (BSHS) – not just some informal gathering but an officially registered and rather venerable learned society aiming to speak for an entire sub-field – issued a statement flatly condemning Bulstrode’s critics for having “neglected both common courtesy and established academic standards, including principles of peer review … We strongly condemn unwarranted attacks on authoritative and innovative research of any kind”. 

Now, I realise that there was a lot of hatred on social media from those who wanted the article to be wrong. Possibly there were more serious threats and complaints made by the mad, bad and sad as well. But with these kinds of statements they have also impugned the motives and integrity of all critics, no matter the quality of their criticism.

And in so doing they have quite dramatically raised the stakes, and with an extraordinary feat of engineering turned a mere molehill – what should have been a “nothing-to-see-here”, mildly reassuring event of academic self-correction and basic accountability – into a mountain. And a mountain from which there is no easy way down. How can they possibly have expected the people who made detailed, still unanswered criticisms not to respond by merely pointing out what is already so obvious even non-expert members of the public? And if the paper remains demonstrably wrong, where do the editors of History & Technology and the council of the BSHS go from there? This is no longer about whether a paper with an eye-catching argument is wrong or right. They allowed themselves to get sucked into the culture warriors’ silly parlour game and totally lost sight of what really matters, because it’s now about whether the run-of-the-mill procedures for getting academic work corrected or retracted actually work at all. It’s about whether they deserve our trust.

I do not wish to get carried away here and claim that this is proof that the entirety of history is in crisis and we need some kind of radical overhaul. Let’s not throw the baby out with the bathwater. But we do need to be confident that the institutions that produce information and correct any resulting misinformation are working properly. If you care about the history of technology, or the history of the Caribbean, or of slavery, or colonialism, or the history of metallurgy, or even history in general – and they’re all big ifs, but personally I love all history and think it all matters – then much like the public the thing we all have in common is that we want our information to be sound. We will never have it all exactly right, and I’m not saying it will ever be perfect – but I think we all want to be moving in the right direction, stumbling our way towards accuracy and truth, not away from them.

Where do we go from here?

Let’s set aside the details of the particular case. Frankly, I hope I never have to publicly mention it ever again. Third time’s the charm, as they say.

But I hope that there are lessons to draw from this about how to conduct historical debate and truly engage with the public, recognising not just the risks and responsibilities of reaching a wider audience, but the major benefits too.

One thing I noticed a lot in the discussion on social media was the questioning of motives. As I keep mentioning, there are a lot of people out there who for whatever reason, even if you try so hard not to be in any way controversial, will fervently want you to be either right or wrong. So it’s very easy to be tempted into questioning people’s motives, because a lot of people’s motives will indeed stem from politics or ideology, whether that’s obvious or not. 

But the questioning of motives is, quite frankly, poisonous. It automatically closes off any chance of healthy or productive public debate. Thoughtful criticism is still thoughtful criticism, no matter its source. Forget this, and we end up in a situation where we assume that criticism cannot be merited, and hubristically close ourselves off to any challenge. 

Take Oliver Jelf. I’ve never met the guy. For all I know, he could be a raving rightwinger or a loonie lefty. But it doesn’t actually matter – in all the correspondence we’ve had, but especially in the work that he made public, his respect for the evidence has spoken for itself. Nor does it matter if his name is real or if he’s a former masters student or a grumpy old professor emeritus: it’s the arguments and evidence that count. 

We also, I think, need to find ways to make it less embarrassing to correct things. This is not just from a personal point of view, but also from an institutional one. We all know we’re fallible and that we make mistakes all the time. It needs to be easier to admit that, correct the record, and move on. It also needs to be much easier to correct records that have already been published and propagated. This applies to peer-reviewed articles, but potentially all the more so to books.  

And we need to brave the public. There’s a risk that this whole saga will put many historians off of actively publicising their work – that they will come to fear the mad, bad, and sad, and all the online abuse it might bring. But I hope it does not. A closed-off history, hidden away behind paywalls or protected by social barriers, is one that will stultify and decay. The public eye may be unforgiving in some senses, but it also exposes your work to new ideas, unfamiliar expertise, and above all creates discipline — if we let it. 

So I have a few, tentative commandments of good public history, to which there are perhaps more to add:

Thou shalt not impugn the motives of those who ask awkward questions.

Thou shalt make it easier to correct the mistakes you make.

Thou shalt go forth and publicise your work.

What might I have missed? What else could or should we do to improve public debate around history? If there’s one thing you do, please take a moment to call me an idiot using the comment button, and then tell me why. 

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