Age of Invention: The Coal Conquest

There was no shortage of trees

You’re reading Age of Invention, my newsletter on the causes of the British Industrial Revolution and the history of innovation, which goes out to over 35,000 people. This is effectively the fourth instalment of this year’s special series on salt. To stay tuned and support the project, subscribe here:

In the last part we looked at how the Dutch took the dirty, solar-evaporated salt of France, Portugal and Spain, known as “bay salt” or black salt, and refined it to a white salt fit for butter, cheese, and preserving herring, which they made by burning their plentiful supplies of peat — the economic underpinning for the seventeenth-century Dutch Golden Age. Soon, however, Dutch peat was to face a new competitor: British coal.

Now, you might think you’re about to hear a very straightforward story. A given cart- or boat-load of even a nice, dry peat yields only about a sixth the heat of the same volume of coal,¹ and only about half the heat by weight.² With that kind of difference in energy density, coal seems like the obvious eventual winner as a source of heat for any industry, not just for refining salt.

But the story turns out to be lot more interesting than that, though we’ll first need to take a very long detour to fully appreciate why. Before we follow the history of salt-making even a single step further, we first need to delve — deeply — into the history of both wood and coal.

Coal Conundrum

It’s long bothered me as to why coal became so important in Britain. It had sat in the ground for millennia, often near the surface. Near Newcastle and Sunderland it was often even strewn out on the beaches.³ Yet coal had largely only been used for some very specific, small-scale uses. It was fired in layers with limestone to produce lime, largely used in mortar for stone and brick buildings. And it had long been popular among blacksmiths, heating iron or steel in a forge before shaping it into weapons or tools.⁴

Although a few places burned coal for heating homes, this was generally only done in places where the coal was an especially pure, hard, and rock-like anthracite, such as in southern Wales and in Lowlands Scotland. Anthracite coal could even be something of a luxury fuel. It was burned in the palaces of the Scottish kings.⁵ But otherwise, the sulphur in the more crumbly and more common coal, like that found near Newcastle, meant that the smoke reeked, reacting with the moisture of people’s eyes to form sulphurous acid, and so making them sting and burn. The very poorest of the poor might resort to it, but the smoke from sulphurous coal fires was heavy and lingering, its soot tarnishing clothes, furnishings, and even skin, whereas a wood fire could be lit in a central open hearth, its smoke simply rising through the rafters and finding its way out through the various crevices and openings of thatched and airy homes. Coal was generally the inferior fuel.

But despite this inferiority, over the course of the late sixteenth century much of the populated eastern coast of England, including the rapidly-expanding city of London, made the switch to burning the stinking, sulphurous, low-grade coal instead of wood.

By far the most common explanation you’ll hear for this dramatic shift, much of which took place over the course of just a few decades c.1570-1600, is that under the pressures of a growing population, with people requiring ever more fuel both for industry and to heat their homes, England saw dramatic deforestation. With firewood in ever shorter supply, its price rose so high as to make coal a more attractive alternative, which despite its problems was at least cheap. This deforestation story is trotted out constantly in books, on museum displays, in conversation, on social media, and often even by experts on coal and iron. I must see or hear it at least once a week, if not more. And there is a mountain of testimonies from contemporaries to back the story up. Again and again, people in the late sixteenth and the seventeenth centuries complained that the woods were disappearing, and that wood fuel prices were on the rise.

And yet the deforestation thesis simply does not work. In fact it makes no sense at all.

Not out of the Woods Yet

This should immediately be obvious from even just a purely theoretical perspective, because wood was almost never exploited for fuel as a one-off resource. It was not like coal or peat or oil, which once dug out of the ground and burned could only be replaced by finding more. It was not a matter of cutting swathes of forest down and burning every branch, stump and root, leaving the land barren and going off in search of more. Our sixteenth-century ancestors were not like Saruman, destroying Fangorn forest for fuel. Instead, acres of forest, and even just the shrubs and trees that made up the hedges separating fields, were carefully maintained to provide a steady yield. The roots of trees were left living and intact, with the wood extracted by cutting away the trunk at the stump, or even just the branches or twigs — a process known as coppicing, and for branches pollarding — so that new trunks or branches would be able to grow back. Although some trees might be left for longer to grow into longer and thicker wood fit for timber, the underwoods were more regularly cropped.⁶

Given forests were treated as a renewable resource, claiming that they were cut down to cause the price of firewood to rise is like claiming that if energy became more expensive today, then we’d use all the water behind a hydroelectric dam and then immediately fill in the reservoir with rubble. Or it’s like claiming that rising food prices would result in farmers harvesting a crop and then immediately concreting over their fields. What actually happens is the precise opposite: when the things people make become more valuable, they tend to expand production, not destroy it. High prices would have prompted the English to rely on forests more, not to cut them down.

When London’s medieval population peaked — first in the 1290s before a devastating famine, and again in the 1340s on the eve of the Black Death — prices of wood fuel began to rise out of all proportion to other goods. But London had plenty of nearby woodland — wood is extremely bulky compared to its value, so trees typically had to be grown as close as possible to the city, or else along the banks of the Thames running through it, or along the nearby coasts. With the rising price of fuel, however, the city did not even have to look much farther afield for its wood, and nearby coastal counties even continued to export firewood across the Channel to the Low Countries (present-day Belgium and the Netherlands) and to the northern coast of France.⁷ A few industries did try to shift to coal, with lime-makers and blacksmiths substituting it for wood more than before, and with brewers and dyers seemingly giving it a try. But the stinking smoke rapidly resulted in the brewers and dyers being banned from using it, and there was certainly no shift to coal being burnt in people’s homes.⁸

As for conditions on the eve of coal’s rapid rise in the late sixteenth century, they were actually even less intense. Following the Black Death, London’s population took centuries to recover, and by 1550 was still below its estimated medieval peak. Having once had over 70-80,000 souls, by 1550 it had only recovered to about 50,000. And the woodlands fuelling London were clearly still intact. Foreign visitors in the 1550s, who mostly stayed close to the city, described the English countryside as “all enclosed with hedges, oaks, and many other sorts of trees, so that in travelling you seem to be in one continued wood”, and remarked that the country had “an abundance of firewood”.⁹ Even in the 1570s, when London’s population had likely begun to finally push past its medieval peak, the city seems to have drawn its wood from a much smaller radius than before. Whereas in the crunch of the 1300s it seemingly needed to draw firewood from as far as 17 miles away over land, in the 1570s even a London MP, with every interest in exaggerating the city’s demands, complained that it only sometimes had to source wood from as far away as just 12 miles.¹⁰

And not far along the coast from the city were also the huge woodlands of the Weald, which stretched across the southeastern counties of Sussex, Surrey and Kent, and which did not even send much of their wood to London at all. Firewood from the Weald was not only exported to the Low Countries and the northern coast of France, but those exports more than tripled between 1490 and the early 1530s, from some 1.5 million billets per year to over 4.7 million. That level was still being reached in 1550, when not interrupted by on-and-off war with France, but by then the Weald was also meeting yet another new demand, for making iron.¹¹

Ironmaking was extremely wood-hungry. In the 1550s Weald, making just a single ton of “pig” or cast iron, fit only for cannon or cooking pots, required almost 4 tons of charcoal, which in turn required roughly another 28 tons or so of seasoned wood. England in the early sixteenth century had imported the vast majority of its iron from Spain, but between 1530 and 1550 Wealden pig iron production increased eightfold. The expansion would have demanded, on a very conservative estimate, the sustained annual output of at least 50,000 acres of woodland — an area over sixty times the size of New York’s Central Park. Yet even this hugely understates the true scale of the expansion, as pig iron needed to be refined into bar or wrought iron in order to be fit for most uses, which required twice as much charcoal again — or in other words, a total of 86 tons of seasoned wood had to be first baked and then burned, just to make one ton of bar iron from the ore. And all this was just the beginning. By the 1590s the output of the Wealden ironworks had more than tripled again, for pig iron alone (though the efficiency of charcoal usage had also halved — a story for another time, perhaps).¹²

Given the rapidity of these changes, it will come as no surprise that there were complaints from the locals about how much the ironworks had increased the price of fuel for their homes. No doubt the wood being exported was having a similar effect as well. But the 1540s and 50s were also time of rapid general inflation, because of a dramatic debasement of the currency initiated by Henry VIII to pay for his wars. This not only made imports significantly more expensive, and so likely spurred much of the activity in the Weald to replace increasingly unaffordable iron from Spain, but they also made exports significantly cheaper for buyers abroad — and thus unaffordable for the English themselves.

In 1548-9, in a desperate bid to keep prices down, royal proclamations repeatedly and futilely banned the export of English wheat, malt, oats, barley, butter, cheese, bacon, beef, tallow, hides, and leather, to which the following year were added — like a game of inflation whack-a-mole — rye, peas, beans, bread, biscuits, mutton, veal, lamb, pork, ale, beer, wool, and candles. And of course charcoal and wood.¹³ For us to have records of the Weald exporting large quantities of wood in 1550 then, they must either have been sold through special royal licence, or have all been shipped out before the ban came in force just halfway through the year in May. Presumably a great deal more than recorded was also smuggled out. In 1555, parliament saw the need to put the ban on exporting victuals and wood into law, adding severe penalties. Transgressing merchants would lose their ship and have to pay a fine worth double the value of the contraband goods, while the ship’s mariners would see all their worldly possessions seized, and be imprisoned for at least a year without bail.¹⁴

It’s perhaps no wonder that the Weald’s ironworks continued to expand at such a rapid pace: the export ban would have freed up a great deal of woodland for their use. And ironmaking soon spread to other parts of England too, to where it did not have to compete for fuel with people’s homes. Given iron was significantly more valuable by both weight and volume than wood, it could easily bear the cost of transporting it from further away, and so could be made much further inland, away from the coasts and rivers whose woodlands served cities. In the early seventeenth century, iron ore and pig iron from the southwest of England was sometimes shipped all the way to well-wooded Ireland for smelting or refining into bar.¹⁵ In the early eighteenth century scrap iron from as far away as even the Netherlands was being recycled in the forested valleys of southwestern Scotland.¹⁶

Whenever ironmaking hit the limits of what could be sustainably grown in an area, it simply expanded into the next place where wood was cheap. And there was almost always another place. England, having had to import some three quarters of its iron from Spain in the 1530s, by the 1580s was almost entirely self-sufficient, after which the total amount of iron it produced using charcoal continued to grow, reaching its peak another two hundred years later in the 1750s.¹⁷ Had iron-making not been able to find sustainable supplies of fuel within England, it would have disappeared within just a few years rather than experiencing almost two centuries of expansion.¹⁸

And that’s just iron. The late sixteenth century also saw the rapid rise in England of a charcoal-hungry glass-making industry too. Green glass for small bottles had long been made in some of England’s forests in small quantities, but large quantities of glass for windows had had to be imported from the Low Countries and France. Just as with iron, however, the effect of debasement was to make the imports unaffordable for the English, and so French workers were enticed over in the 1550s and 60s to make window glass in the Weald. Soon afterwards, Venetian-style crystal-clear drinking glasses were being made there too.

What makes glass even more interesting than iron, however, is that its breakability meant it could not be made too far away from the cities in which it would be sold, and so had to compete directly with people’s homes for its fuel. Yet by the 1570s crystal glass was even being made even within London itself. Despite charcoal supplies being by far the largest cost of production, over the course of the late sixteenth century the price of glass in England remained stable, making it increasingly common and affordable while the price of pretty much everything else rose.¹⁹

What we have then is not evidence of a mid-sixteenth-century shortage of wood for fuel, and certainly not of those demands causing deforestation. It is instead evidence of truly unprecedented demands being generally and sustainably met.

And despite these unprecedented demands, the intensity with which under-woods were exploited for fuel seems to have actually decreased. During the medieval population peaks, the woods and hedges that supplied London had been squeezed for more fuel by simply cropping the trunks and branches more often, cutting them away every six or seven years rather than waiting for them to grow into larger poles or logs. After the Black Death killed off half the population, the cropping cycle could again lengthen to about eleven. But under-woods in the mid-sixteenth century were being cropped on average only twelve or so years — about twice as long a cycle as before the Black Death — which by the nineteenth century had lengthened still further to fourteen or fifteen.²⁰

The lengthening of the cropping cycle can imply a number of things, and we’ll get to them all. But one possibility is that in order to meet unprecedented demands, more firewood was being collected at the expense of the other major use of trees: for timber.

Preserving the Planks

To be used as timber for tools, carts, furniture, ploughs, buildings, and ships, trees need to be allowed to grow a very long time. Whereas coppices could be cut for fuel after just a handful of years, a typical elm would not be ready to be used as timber in a ship for at least a few decades, and an oak for a century. Growing timber could often be a multi-generational affair, and it was typically only preserved by those with a permanent interest in the land on which it grew — the families of the nobility and gentry who owned it. (Even these aristocrats, however, were often be tempted to fell a tree early to meet their own expenses rather than allowing it to grow to maturity to benefit their children or even grandchildren. They could be especially tempted when times were tough, or when fuel was in high demand.) Given timber had a much greater value per volume than firewood, it could also bear the cost of being transported from much further inland, or even imported from Norway or the Baltic. Indeed, sourcing timber from further afield allowed the trees planted closer to London to concentrate on producing fuel — something that made the coppices even more efficient, too, because the taller timber trees would no longer put the twiggy underwood exploited for fuel in the shade.²¹

Yet timber was, increasingly, a material of war. In the 1540s, in preparation for an invasion of France, Henry VIII oversaw the biggest build-up of the royal navy that England had ever seen. For a few years at least, timber must have been in higher demand than at any time before. But given their slow-growing nature, domestic supplies could not immediately be expanded to meet demand. Other than buying timber from abroad, and so potentially placing England at the mercy of other countries, domestic supplies would at best have a decades-long lag, and may not have responded by expanding at all, unless people believed that the demand for timber would still be much higher in a few decades’ time. And so in 1543 Parliament began the first of many moves to create a strategic timber reserve, requiring that for every acre of coppice exploited for fuel, at least twelve trees were to be left standing to grow into timber, on pain of a fine.²²

The Weald was exempted, perhaps because iron was just as important for national defence, but Parliament soon began to worry about how to balance the rival demands. In 1559 it forbade the felling for ironmaking of any oak, beech or ash tree that was already a square foot at the base (just under 930cm squared). Underwood could still of course be used, which ironmakers had every incentive to grow. And the restriction only applied to within fourteen miles of any major river or the coast, again exempting the Weald, so that any timber further inland — apart from that already protected by the 1543 statute — would still be fair game.²³

By 1572, however, Parliament was again discussing whether it needed to introduce even more protections for timber — the first time we have some record of the actual debate. The proposal was to stop the iron industry from using any wood at all within twenty miles of London, but it was hotly opposed by members of Parliament with constituencies in the Weald. One pointed out that there were Wealden woods within that range that had never supplied wood to London at all. Another argued that there was no major scarcity of wood to justify such a major restriction on how the owners of woodland used their own property. And another noted that given the aim of the proposal was to preserve timber, which was already protected by the 1559 law, it was puzzling as to why they should restrict ironworks from felling underwood too.

Against them, however, the MPs for London and its surroundings explicitly noted that if more ironworks were allowed to increase the demand for fuel, then they would of course prevent trees from being allowed to grow into timber: “It has been said [the bill] is no help for preservation of timber, but experience shall show that if coppicewood be consumed, the timber trees must needs be cut down for provision of fuel for the City.” They even complained that London was beginning to lose some of its woodworking trades. The city had apparently, though rather improbably, already lost all its makers of wooden frames for saddles.²⁴ Yet the need cannot have been all that pressing or convincing to their fellow MPs. The bill managed to become law only nine years later in 1581, when it restricted all ironworks from operating within 22 miles of London or the Thames. And again the Weald was exempted, save for a few miles around some nearby port towns.²⁵ Only as late as 1585 was the Weald’s special exemption from the old 1559 regulations removed, and this only brought it in line with the rules being followed by every other iron-making region in the country.²⁶

Iron was not, of course, the only threat to the strategic timber reserve. In 1559, Elizabeth I issued a proclamation to forbid the sale of any English-made ships to foreigners, effectively banning a major form of timber export.²⁷ And in 1605 her successor James I was to issue a proclamation banning the building of any new houses in or around London, on the grounds that timber was in short supply for the navy, and because Londoners had resorted to using cheap beech instead of longer-lasting oak. The only exception he allowed was for buildings whose facades and walls were made entirely of stone or brick, which had the advantage of being less of a fire hazard too.²⁸ By 1615, James — who was also James VI of Scotland, and having succeeded to the English throne liked to style himself the first ruler of a united Great Britain — was hopeful that much like it had been said of the first Roman emperor Augustus that he had found Rome a city of brick and left it a city of marble, so “the first king of Great Britain might be able to say in some proportion, that we had found our city and suburbs of London of sticks, and left them of brick.”²⁹

Worrying about maintaining a large strategic timber reserve, however, is not the same as timber facing an actual shortage. Before James’s proclamation, London had already quadrupled in population over the course of 1550-1600, and was continuing to grow. Yet it still managed to find the timber for building, and even managed to rebuild vast swathes of the city all at once following the Great Fire of 1666 (though this rebuilding did, as you’d expect, cause timber prices to temporarily spike). Both England’s navy and its much larger merchant marine grew considerably at the same time too, with the merchant fleet doubling in tonnage between the 1560s and 1629, and more than doubling again by 1686.³⁰ Yet even despite this extraordinary growth, by the nineteenth century more timber than had been used in the construction of the entire English merchant fleet afloat in 1629 could be consumed for shipbuilding in just some single years.³¹

A lot of England’s timber need was met by importing it from Scandinavia and the Baltic. But the country’s own timber reserves also seem to have held up. Massive ocean-going ships being built in the 1620s were able to source their timber from counties close to London like Essex and Kent, with little apparent effect on prices.³² And those same counties were still producing timber a hundred years on. The Suffolk town of Ipswich, not far up the coast from London, was said to have “plenty of timber and plank” for shipbuilding in the 1610s,³³ and was said to have “an inexhaustible storehouse of timber” over a hundred years after that.³⁴ By the 1720s much the same was said of the timber of the Weald, even though the region still produced iron, while the southern coastal county of Hampshire, which supplied the massive demands of the royal shipyards at Portsmouth, was growing timber in such plenty that many of its older oaks had been left to grow too long, past maturity, and could no longer be used.³⁵ And that was not even to mention the timber grown up-river from London in the inland counties of Hertfordshire, Berkshire, and Buckinghamshire. Buckinghamshire in the 1720s was said to be overgrown with beech, used in London for making the wheels of carts and all sorts of furniture.³⁶ Just as with wood fuel, the story of English timber was not one of shortage, but of growing and unprecedented demands being generally met.

Yet despite the lack of any major shortage of either firewood or timber, after 1570 England did experience dramatic deforestation.

Fuel versus Food

Although firewood was needed to heat people’s homes, trees were also fiercely competing for space with crops and grass. Nobody ever destroyed woodland because of the demand for wood or timber, but they did grub up trees by their roots to convert the land beneath them into ploughable fields, vegetable gardens, or pasture. The original 1543 legislation, which preserved a certain amount of timber trees for every acre of coppice, also forbade those coppices from first being grubbed up for pasture or tillage. But it seems not to have had much effect. As one chronicler put it in 1577, “every small occasion in my time is enough to cut down a great wood”³⁷, while in 1607 a forest surveyor judged that within the previous two decades the country’s woodlands had receded by two thirds. Wood was, he said, was now “rather held a hurtful weed than a profitable fruit, and therefore the wasting of it held providence, to the end that corn, a more profitable increase, might be brought in instead of it.”³⁸ In other words, it was increasingly considered mere prudence to deforest an area and sow it with more profitable grain.

By the 1610s, woodland was said to be just a third the value of pasture.³⁹ And by the 1680s, the apothecary John Houghton, a fellow of the Royal Society with a sophisticated understanding of both economics and agriculture, was even arguing that all woodland within twelve miles of any major river — the places where wood had been most essential — actually ought to be grubbed up. Because farmland yielded over three times as much annual income per acre, that added income that could be used to simply buy the timber and fuel from further inland or abroad. And farmland and its products provided a lot more employment than any woodland too.⁴⁰

This is not to say that woodland wasn’t valued at all. A Swedish visitor in the 1740s was actually extremely impressed with the English for never wasting their wood. He noted how they carefully gathered up their sawdust, any shavings from carpentry, and even fallen leaves, all to be left to dry and then used as fuel. Even when he witnessed woodlands being destroyed, he admired how the stumps and roots were never left to waste but chopped up and used. “The people here know”, he admired, “how to place the right value on woodland and to take care of such a precious resource”.⁴¹

But the ancient balance between food and fuel was being drastically changed, and the thing that tipped the scales was the arrival of a much cheaper fuel for people’s homes. What changed was the arrival of coal.

The Land that Coal Made

Wherever coal could go, Britain’s Fangorns gave way to the neat fields and hedgerows of The Shire. As one writer put it in the 1690s, “where wood fuel is … supplanted by that of coals, men are easily tempted to quit the preservation of their woods and convert their ground to tillage in hopes to find more advantage”.⁴² Wherever coal appeared, land that previously had to be devoted to fuel — mostly wood, but also peat-filled marshland and gorse-covered heath — was rapidly converted to agriculture instead.

In fact, Britain’s whole landscape seemed to invert, reversing the pattern that had held for centuries. Whereas coppices had always needed to be close to the major rivers and coasts, or within a few miles overland of London, from the 1570s many of these woods were among the first to go.

This was because coal invaded from the coasts. Because coal was so heavy, it was extremely expensive to transport over long distances by land, but relatively easy by river or sea. Carrying it overland for just 10 miles (or 16 kilometres), cost about the same as transporting it a whopping 250 miles (or 402 kilometres) by ship — twenty-five times as far.⁴³ It even came to be most commonly called “sea coal”, mere “coal” usually meaning charcoal instead.⁴⁴ Other than the places closest to the coal mines themselves, or where there was some other local fuel available like peat or furze, the first areas to experience deforestation were often those where coal could wend its way by water.

In the coal-rich Lowlands Scotland, which by 1500 was already almost devoid of trees,⁴⁵ a foreign visitor in the 1710s wondered at how “Nature has provided coal in several places where it was so much the more necessary for want of wood”.⁴⁶ Yet Nature was apparently generous everywhere else as well. The Isle of Man, off England’s northwestern coast, was by the 1570 described as being devoid of wood — it imported coal from the mines of Cumbria.⁴⁷ On England’s northeastern coast in the 1570s, “great woods have been, but now utterly decayed and no wood at all remains” — this was just up the coast from where Newcastle’s coal was mined.⁴⁸ The land all around Dublin in 1600 was full of rich pasture and farmland while “wanting wood” — it had some local turf, but also imported “coal brought out of England”.⁴⁹ Western Cornwall at about the same time was said to lack trees too — as well as turf, its homes were largely heated “by stone coal, fetched out of Wales”.⁵⁰ And meanwhile in southern Wales itself, one writer described how “those that dwell near the coal, or that may have it carried by water with ease, use most coal fires in their kitchens, and some in their halls”, while also noting — again without making the connection — that its “diverse great corn fields were in times past great forests and woods.”⁵¹ It was, of course, no providential coincidence at all.

The scars of coal’s seaborne invasion were even reflected in the very hedges dividing the fields. A Swedish botanist visiting England in the 1740s noted how closer to London and its river, the Thames, the fields were divided by mere earthen banks and ditches, often covered with grass to maximise pasturage, while smaller gardens were enclosed by brick walls. A little further inland, the banks were increasingly topped by short bushes that provided a little fuel, with the walls giving way to fences of sticks or recycled timber planks. And a few miles inland, where coal was most costly, both bank and fence gave way to thick hedge, often interspersed with taller timber trees.⁵²

This pattern could not have occurred thanks to the demands of a growing population. Extra people needed both food and warmth to survive, and when population peaked before the Black Death, the woodlands near London had been relied upon more than ever rather than being grubbed up. Without coal, the pressure of a growing population would have created a landscape more akin to that described by an English visitor to northern Italy at the start of the seventeenth century, who reported how farmers were forced to “make use of the very furrows between the acres, for as in the acre he sows corn, so in the furrows he plants elm trees, the lopping whereof serve him to burn”.⁵³ In over-populated Italy at the tail end of its Renaissance, the lack of an alternative fuel meant that crops and trees had to be crammed into the same space, which then had to compete with one another for sunshine and nutrients, usually to the detriment of both.

In Britain, by contrast, crops and trees did not have to share space, and so fewer trees were needed at all. The rise of coal was not caused by deforestation. Deforestation was caused by the arrival of cheap coal.

Axes as Allies: Guardians of the Grove

Throughout the late sixteenth and early seventeenth centuries, dozens of petitioners for patents emphasised how their inventions could save the kingdom’s firewood and timber, and help bring down its price. Usually they suggested doing this by replacing the use of charcoal with peat or coal. But, ironically, whenever their inventions were successful they had the opposite effect.

For it soon became obvious that industry’s huge hunger for wood was one of the only things that prevented deforestation in the lands that coal had invaded.⁵⁴ Wood-less, coal-dependent western Cornwall in 1600 clearly could grow trees if it wanted to — it did actually have a few coppices, but only wherever charcoal was needed to smelt the region’s tin.⁵⁵ And by the 1720s one of the few major woods to cling on just southeast of London was mainly supplying a kind of kindling largely used in the upstairs bedrooms of the city’s taverns, presumably because they had not yet all had fireplaces installed for burning coal.⁵⁶

Many trees were also kept around by demand for timber — the woods of Berkshire and Buckinghamshire increasingly specialised away from producing fuel, to instead supply London’s woodworking trades — as well as by demand for fruit. Kent, for example, was famous for its many cherry orchards. And plenty of trees were planted for the gentry’s hunting grounds and parks, or for shade and decoration, much like those that line our city streets today — which we now don’t think about as sources of firewood at all. Perhaps most importantly of all, an untold quantity of oak bark was required for tannin, used to treat animal hides into leather. In the 1670s the inventor Charles Howard, younger brother of the fifth duke of Norfolk, even developed a way to extract tannin from all the other parts of an oak tree, and from other trees as well — a technique that he hoped would “greatly improve the value of under-woods”, providing the demand to help preserve them from agriculture’s advance.⁵⁷

Even iron-making, having once been seen as the enemy of timber, was soon recognised as one of the only things keeping the more accessible woodlands standing. After imported iron from Sweden began putting many English ironworks out of business, by the 1670s commentators were worrying at how their closure was only accelerating deforestation: “for when ironworks were carried on, both wood and [char]coals would yield ready moneys, which encouraged the owners not only to preserve the coppices and woods from destruction, but also to plant and promote more”, whereas now, “for want of ironworks they are destroyed, both wood and timber, root and branch, and that more and more every year”.⁵⁸

And so the same thing happened in industry after industry whenever coal could take wood’s place. Take those woods that had managed to cling on just southeast of London to provide wood for tavern bedrooms. Once the taverns started “to make coal fires in their upper rooms”, one writer observed, “what an alteration it makes in the value of those woods … and how many more of them than usual are yearly stubbed up, and the land made fit for the plough”.⁵⁹

Much the same thing happened when glassmakers made the switch to using coal in the early 1610s. As members of Parliament later put it when investigating the patent for making glass with coal, one of the big problems was that “as it makes wood cheap it makes the coal dearer” — a sure-fire way to accelerate deforestation while raising the price of the only alternative fuel for people’s homes.⁶⁰ Indeed, when the patent was first being applied for in 1610, the objection was raised that “gentlemen well wooded would be hindered in the sale of their woods” — to which the patentees responded by arguing that because they would have a monopoly on the technique, they would actually keep wood prices high by preventing other glassmakers from making the switch from wood to coal!⁶¹ (Considering that just a few years later the patentees then persuaded the king to ban the use of wood for making glass entirely, they were clearly willing to make whatever convoluted argument was necessary just to get their way.)

Indeed, worries about deforestation were seemingly at their loudest when the glass industry was making the switch. If we look more closely at the complaints at the time, they were actually written about problems with the supply of coal, not of wood — just like how in recent years many countries happily imported natural gas instead of investing in nuclear power, but then their politicians and pundits only lamented the lack of nuclear when Russia’s invasion of Ukraine disrupted the supply of gas. People cared most about wood only when something happened to the fuel that had replaced it. As the 1610s writer Arthur Standish put it, “it is apparent that coal mines do decay too fast in most countries”, especially inland, where having already grubbed up the trees, the sudden lack of coal meant that many of the poorest in those regions now had to resort to burning cow dung as fuel instead. Catastrophe loomed, he warned, if the coal sent by the coast were to run out as well.

Nobody, Standish pointed out, had back in the 1570s been worried about a lack of wood — it was then thought “a thing impossible”, when even “the poorest sort scorned to eat a piece of meat roasted with sea coals”, as many of the rich now did. But with the country having become dependent on coal, “with much more reason may it now be feared that in the like time coals may be more decayed”. Coals, he pointed out, could “never more grow or increase”, whereas wood was at least a sustainable source.⁶² As another author starkly put it, “if coal should fail (as it is too apparent it begins to grow dear and scarce, and in many places there is none to be had) how then should we do for … fuel?”⁶³ Then, just as now, the lack of a particular fuel only became truly stark when the alternative everyone had come to depend on was suddenly in doubt. Even the king backed Standish’s book.⁶⁴

But although the pundits and politicians of the 1610s worried that the coal supply was on the brink of actual exhaustion, the effects of new demand for coal from glass furnaces would have looked pretty similar from the perspective of ordinary people simply trying to buy the fuel to heat their own home. All they would have really seen was the increased price. Indeed, the last time there had been widespread complaints of a fuel shortage in London, in 1603, was not long after the imposition of a tax on all coal shipped by sea — one that was removed, after lots of complaints, only from Ireland, the Isle of Man, the Channel Islands, and western Scotland. Poor Londoners were stuck with having to simply make do, perhaps following the advice of the inventor Hugh Plat, who not only suggested the planting of fast-growing willow trees, but in the meantime had plenty of tips on how to purify the cheapest and stinkiest of coals.⁶⁵

Now, some might wonder why increases to the price of coal, if wood was being simultaneously made cheaper, did not result in people flocking back to burning wood again. After all, growing trees did seem more sustainable, and it’s not like lots of people hadn’t also been sounding the alarm on coal dependence for many years. A forest surveyor in 1607, writing of a county since swallowed up by London’s expansion, cried “who sees not that the general extirpation and stocking up of coppice ground in Middlesex will not breed want to them that shall succeed?” He warned that land, “if all for corn and grass, it were like Midas his wish” — enriching in the short-term, but soon to be lamented as a curse.⁶⁶ But the problem was that coal almost always responded much faster to increased prices than wood ever could.

Not only did the coal never run out — there’s still plenty in the ground, even though the UK closed its last coal-fuelled power plant earlier this week — but whenever one mine failed or demand for coal increased, there turned out to almost always be yet another seam that could be exploited by simply and quickly digging another pit nearby. Planting new trees, by contrast, was a slow and risky business, so that by the time a tree had grown enough to yield any fuel, prices might have fallen back down again. And to make matters worse, newly-sprouted trees had to be fenced off and defended from both wild animals and hungry cattle for years, so that vast tracts of land could not even, in the meantime, provide any income from pasture. Whereas the cost of digging a coal mine was simply the time and money spent on actually digging it, the cost of planting woodland also included the massive loss from no longer using that land for food.

So whenever fuel prices increased, coal pretty much always beat wood to the punch. And whenever fuel prices decreased, only woodland retreated because there was so much more that the land could be used for instead. Coal mines might occasionally cease to be worked from lack of demand, but being otherwise worthless they could be almost instantly re-opened when things recovered, in a way that woodland converted to agricultural land could not. Coal supply was immediately able to advance, whereas woodland at best resisted retreat. Once coal had arrived, it was almost impossible for wood to fight back.

It’s no wonder that people at the time complained of a wood shortage and frequently noted how wood’s prices were on the rise. After all, wherever coal replaced it first as a fuel for people’s homes, and then in blacksmithing, brewing, glass-making, iron-making, and more, what little woodland was left was only kept around for a dwindling number of well-paying industries and for the recreation of the rich. Such a diminished supply was going to be far too expensive for ordinary people with much smaller budgets for fuelling their homes. Yet although prices of wood rose, this was the inevitable consequence, not the cause, of coal’s rise.

The cause of coal’s rise was, instead, that from the 1570s it very suddenly became very cheap, making itself a lot more attractive as a fuel for people’s homes, and encouraging them to adopt it even when they lived hundreds of miles away from the source. And the reason for that sudden change, I’ve discovered, had a great deal to do with salt. More on that next time.

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

1. Zeeuw, J. W. de. ‘Peat and the Dutch Golden Age: The Historical Meaning of Energy-Attainability’. AAG Bijdragen 21 (1978), pp.3–31.

2. E. A. Wrigley, Continuity, Chance and Change: The Character of the Industrial Revolution in England (Cambridge University Press, 1990), p.59

3. Ruth Goodman, The Domestic Revolution (Michael O’Mara Books, 2020), p.91

4. James A. Galloway, Derek Keene, and Margaret Murphy, ‘Fuelling the City: Production and Distribution of Firewood and Fuel in London’s Region, 1290-1400’, The Economic History Review 49, no. 3 (1996): pp.447–9

5. J. U. Nef, The Rise of the British Coal Industry, Vol. 1 (London: George Routledge and Sons, 1932), p.107, pp.115-8

6. Oliver Rackham, Ancient Woodland: Its History, Vegetation and Uses in England (Edward Arnold, 1980), pp.3-6 is the best and clearest summary I have seen.

7. Galloway et al.

8. John Hatcher, The History of the British Coal Industry: Volume 1: Before 1700: Towards the Age of Coal (Oxford University Press, 1993), p.25

9. Estienne Perlin, “A description of England and Scotland” [1558], in The Antiquarian Repertory, vol.1 (1775), p.231. Perlin must have visited Britain in early 1553, as he mentions the arrival of a new French ambassador, which occurred in April 1553, as well as the wedding of Lady Jane Grey, which occurred in May of that year. Also Danielo Barbaro, ‘Report (May 1551)’ in Calendar of State Papers Relating to English Affairs in the Archives of Venice, Vol 5: 1534-1554 (Her Majesty’s Stationery Office, 1873). And: Paul Warde and Tom Williamson, ‘Fuel Supply and Agriculture in Post-Medieval England’, The Agricultural History Review 62, no. 1 (2014), p.71

10. Galloway et al., p.457 for the estimate of 17.4 miles overland as the outer limit of London’s firewood supply; Proceedings in the Parliaments of Elizabeth I, Vol I: 1558-1581, ed. T.E. Hartley (Leicester University Press, 1981), p.370: specifically, the London MP Rowland Hayward complained of the cost of firewood billets and charcoal having increased in price over the previous 30 years (which would encompass the period of debasement-induced inflation), before noting that “Sometimes the want of wood has driven the City to make provision in such places as they have been driven to carry it 12 miles by land”.

11. Mavis E. Mate, Trade and Economic Developments, 1450-1550: The Experience of Kent, Surrey and Sussex (Boydell Press, 2006), pp.83, 92, 101

12. These statistics are derived from a combination of Peter King, ‘The Production and Consumption of Bar Iron in Early Modern England and Wales’, The Economic History Review 58, no. 1 (1 February 2005), pp.1–33 for the iron production estimates, and G. Hammersley, ‘The Charcoal Iron Industry and Its Fuel, 1540-1750’, The Economic History Review 26, no. 4 (1973), pp.593–613 for the estimates of how much charcoal, wood, and land was required at a given date to produce a given quantity of pig or bar iron.

13. Paul L. Hughes and James F. Larkin, eds., Tudor Royal Proclamations., Vol. I: The Early Tudors (1485-1553) (Yale University Press, 1964), proclamations nos. 304, 310, 318, 319, 345, 357, 361, 365, 366.

14. 1 & 2 Philip & Mary, c.5 (1555)

15. William Brereton, Travels in Holland, the United Provinces, England, Scotland and Ireland 1634-1635, ed. Edward Hawkins (The Chetham Society, 1844), p.147

16. T. C. Smout, ed., ‘Journal of Henry Kalmeter’s Travels in Scotland, 1719-20’, in Scottish Industrial History: A Miscellany, vol. 14, 4 (Scottish History Society, 1978), p.19

17. See King. Note that there was an interruption to this growth in the mid-seventeenth century, for reasons I mention later on.

18. There was a period in the early-to-mid seventeenth century when English ironmaking stagnated, but this was due to the growth of a competitive ironmaking industry in Sweden.

19. D. W. Crossley, ‘The Performance of the Glass Industry in Sixteenth-Century England’, The Economic History Review 25, no. 3 (1972), pp.421–33

20. Galloway et al. On cropping cycles in particular, see pp.454-5: they note how the average cropping of wood in their sample c.1300 was about every seven years, but by 1375-1400 — once population pressures had receded due to the Black Death — the average had increased to every eleven. See also Rackham, pp.140-1. John Worlidge, Systema agriculturæ (1675), p.96 mentions that coppice “of twelve or fifteen years are esteemed fit for the axe. But those of twenty years’ standing are better, and far advance the price. Seventeen years’ growth affords a tolerable fell.”

21. Rackham, pp.151, 153

22. 34-35 Hen 8, c.3 (1543)

23. 1 Eliz 1, c.15 (1559)

24. Proceedings in the Parliaments of Elizabeth I, Vol I: 1558-1581, ed. T.E. Hartley (Leicester University Press, 1981), p.370. The note about no more saddletree makers left seemingly came from Thomas Cure, MP for East Grinstead between London and the Weald. Thomas Norton, the MP for London, made the point about competition between fuel and timber so explicitly.

25. 23 Eliz 1, c.5 (1581)

26. 27 Eliz 1, c.19 (1585)

27. ed. Paul L. Hughes and James F Larkin, Tudor Royal Proclamations, Volume II (Yale University Press, 1964)

28. ed. Paul L. Hughes and James F Larkin, Stuart Royal Proclamations, Volume I: Royal Proclamations of King James I, 1603-1625 (Oxford University Press, 1973), no.51

29. Ibid, no.152

30. Ralph Davis, The Rise of the English Shipping Industry in the Seventeenth and Eighteenth Centuries (Oxford University Press, 2012), p.14

31. Rackham, p.153

32. Thomas Mun, Discourse of Trade (1621), p.30; and Defoe, p.147 for Kent and Essex still being mentioned as major sources of oak timber in the 1720s.

33. Tobias Gentleman, England’s Way to Win Wealth (1614), p.22

34. Daniel Defoe, A Tour Thro’ the Whole Island of Great Britain, Vol I (1724), p.69. He had much the same to say about the Weald, p.54

35. Ibid, p.78

36. Ibid, p.72

37. William Harrison, The firste volume of the chronicles of England, Scotlande, and Ireland (1577), p.91

38. John Norden, The surueyors dialogue (1607), p.214

39. Arthur Standish, The Commons Complaint (1611), p.5, who responded to this fact by arguing that more could be done to raise its value through breeding waterfowl or planting trees on grounds ill-suited to farming]

40. John Houghton, “An essay to prove that if no wood for fuel or timber grew within 12 miles of a navigable river within this kingdom, it would be its great advantage”, in Collection of Letters on Husbandry and Trade, Vol II, no.3, (6 November 1683)

41. ‘Pehr Kalm’, in The Linnaeus Apostles: Global Science and Adventure Vol III, Book I (IK Foundation & Co, 2008), pp.151, 156-7, 169, 181, 190, 208

42. Timothy Nourse, Campania fœlix (1700), p.360. Intriguingly, he made this argument in an essay arguing for coal-burning to be banned from London because of the pollution it caused. I have written “in the 1690s” because this work was only published after his death in 1699.

43. Goodman, p.92

44. The other names for mineral coal were “pit coal” (usually for inland coal mines), “earth coal”, “stone coal” (usually for rock-hard anthracite), or “cannel coal” (coals that could be used as a candle, like those found near Wigan, which burned brightly and were sometimes polished into jet items, but were less effective at giving off heat.)

45. T. C. Smout, History of the Native Woodlands of Scotland 1500-1920 (Edinburgh University Press, 2007), pp.38-40

46. T. C. Smout, ed., ‘Journal of Henry Kalmeter’, p.16. See also Fynes Moryson, An itinerary … containing his ten yeeres travell (1617), p.274, an English visitor in 1600: “the land yields corn and pasture and sea coals … though trees are so rare in those parts, as I remember not to have seen one wood.”

47. Abraham Ortelius, Theatrum orbis terrarum, or Theatre of the Whole World (John Norton, [1570] 1606), in ‘Of the Orkeny Iles, West Iles, Man, &c’

48. Nef, p.150

49. Moryson, p.158

50. Richard Carew, The Survey of Cornwall (1602), p.21

51. George Owen, ‘A History of Pembrokeshire’ [1603], in The Cambrian Register for the Year 1796, Vol II, (1799), pp.103-4

52. Kalm, pp.230, 237, 247, 264, 286, 289, 322, 333, 340

53. Moryson, p.109

54. David Crossley, ‘English Woodlands and the Supply of Fuel for Industry’, Industrial Archaeology Review, 27, no. 1 (May 2005), pp.105–12. There are two other things worth mentioning, which prevented deforestation. One was when the soil was too poor for alternative uses. The other was when the residents near a wood had certain rights over the felling of firewood in certain areas — common rights, though more accurately residents’ privileges, that could only be extinguished by getting them all to agree to renounce them, often at great cost, before the land could be converted to agriculture.

55. Carew, p.21

56. Defoe, pp.12-13

57. Charles Howard, ‘Brief Directions how to Tan Leather, according to the new invention of the Honourable Charles Howard of Norfolk’, Philosophical Transactions of the Royal Society 9, no.105 (20 July 1674), pp.93-6]

58. Richard Haines, The Prevention of Poverty (1674), p.8. Note how even proponents of growing more woodland agreed, e.g. John Worlidge, The second parts of Systema agriculturae (1689), p.62: “The due felling of woods does likewise produce an increase of the same species: witness the constant felling of woods … in Sussex, for the supply of the ironworks there. There gain arising from thence encourages the owners of those woods to propagate and preserve them.” See also the arguments made by Andrew Yarranton, England's improvement by sea and land, Vol I (1677), pp.59-61

59. Defoe pp.12-13

60. Maija Jansson ed. Proceedings in Parliament 1614 (House of Commons), Memoirs of the American Philosophical Society Vol 172 (1988), p.138

61. Eleanor Smith Godfrey, The Development of English Glassmaking, 1560-1640 (University of North Carolina Press, 1975), pp.60-1

62. Standish 1611, p.6; p.2 on the resort to burning cow dung; see also the 1613 edition of Standish, pp.34-5, and its conclusion on p.36 that “to the end that sea coals shall decay, good take-heed come not too late”

63. Rooke Churche, An Old Thrift Newly Revived (1612), in the dedication to the Earl of Northampton

64. James I/VI seems to have taken this issue quite seriously. In 1609 he also banned the export of Scottish coal on the grounds that it might run out. Replying to his Scottish ministers, who had sent him some objections, he asked “what the case of that country will be when it is once spent … for howsoever you would now be prodigal of it, yet hardly hereafter could you endure the want thereof”.

65. Hugh Plat, A New, Cheap and Delicate Fire of Cole-Balles (1603); and Nef, Vol 2, p.220. A few years later an exemption was, however, secured specifically for the London poor.

66. Norden, p.217