Why Was There No Roman Industrial Revolution?

I came across an interesting article with the above title by Dr Bret Devereaux who teaches at North Carolina State University. I have abridged it herein. It is an interesting explanation of why the Industrial Revolution started in Great Britain and not elsewhere or at a different time in history such as Roman times.

The Roman empire had many features of a modern industrial society. A large single market covering a significant proportion of the worlds then population. An excellent communication network via their road building skills. And yet it remained an agrarian economy, perhaps an efficient one with areas specialising in specific crops and a large (enslaved) workforce (no differences then!!!!!). Being a particularly complex or efficient agrarian economy doesn’t seem to have been the most important thing for producing the industrial revolution. If it had it almost certainly would have happened earlier and probably not in Europe.

The first key is understanding that the industrial revolution was more than simply an increase in economic production. Instead, the industrial revolution was about accessing entirely new sources of energy for broad use in the economy, thus drastically increasing the amount of power available for human use. The industrial revolution thus represents not merely a change in quantity, but a change in kind from what we might call an ‘organic’ economy to a ‘mineral’ economy.

Unlike farming which developed independently in many places at different times, the industrial revolution happened largely in one place, once and then spread out from there. Fundamentally this is a story about coal, steam engines, textile manufacture and above all the harnessing of a new source of energy in the economy. That’s not the whole story, by any means, but it is an important aspect. Each innovation in the chain required not merely the discovery of the principle, but also the design and an economically viable end use to all line up in order to have impact.

The steam engine is an excellent example of this problem. Early tinkering with the idea of using heat to create steam to power rotary motion – the core function of a steam-engine – go all the way back to Vitruvius (c. 80 BC -15 AD) and Heron of Alexandria (c. 10-70 AD). With the benefit of hindsight we can see they were tinkering with an important principle but the devices they actually produced – the aeolipile – had no practical use – it’s fearsomely fuel inefficient, produces little power and has to be refilled with water (that then has to be heated again from room temperature to enable operation).

So what was needed was not merely the idea of using steam, but also a design which could actually function in a specific use case.

In practice that meant both a design that was far more efficient (though early designs were still wildly inefficient) and a use case that could tolerate the inevitable inadequacies of a version 1.0 device. The first design to actually square this circle was Thomas Newcomen’s atmospheric steam engine (1712). Though a substantial improvement on previous efforts, the Newcomen engine had all sorts of limitations: the power it could produce was limited to atmospheric pressure, the motion it created was jerky rather than smooth and most importantly it was hideously fuel inefficient.

Now that design would be iterated on to produce smoother, more powerful and more efficient engines, but for that iteration to happen someone needs to be using it, meaning there needs to be a use-case for repetitive motion at modest but significant power in an environment where fuel is extremely cheap so that the inefficiency of the engine didn’t make it a worse option than simply having a whole bunch of burly fellows (or draft animals) do the job. As we’ll see, this was a use-case that didn’t really exist in the ancient world and indeed existed almost nowhere but Britain even in the period where it worked.

Fortunately for Newcomen the use case did exist at that moment: pumping water out of coal mines. A mine that runs below the local water-table (as most do) is going to naturally fill with water which has to be pumped out. Traditionally this was done with muscle power, but as mines get deeper the power needed to pump out the water increases; cheaper and more effective pumping mechanisms were thus very desirable for mining. But the incentive here can’t just be any sort of mining, it has to be coal mining because of the inefficiency problem: coal (a fuel you can run the engine on) is of course going to be very cheap and abundant directly above the mine where it is being produced and for the atmospheric engine to make sense as an investment the fuel must be very cheap indeed. It would not have made economic sense to use an atmospheric steam engine over simply adding more muscle if you were mining, say, iron or gold and had to ship the fuel in; transportation costs for bulk goods in the pre-railroad world were high. And trying to run your atmospheric engine off of local timber would only work for a very little while before the trees you needed were quite far away.

But that in turn requires you to have large coal mines, mining lots of coal deep underground. Which in turn demands that your society has some sort of bulk use for coal. But just as the Newcomen Engine needed to out-compete ‘more muscle’ to get a foothold, coal has its own competitor: wood and charcoal. There is scattered evidence for limited use of coal as a fuel from the ancient period in many places in the world, but there needs to be a lot of demand to push mines deep to create the demand for pumping. In this regard, the situation on Great Britain (the island, specifically) was almost ideal: most of Great Britain’s forests seem to have been cleared for agriculture in antiquity; by 1000 only about 15% of England (as a geographic sub-unit of the island) was forested, a figure which continued to decline rapidly in the centuries that followed (down to a low of around 5%). Consequently, wood as a heat fuel was scarce and so beginning in the 16th century, we see a marked shift over to coal as a heating fuel for things like cooking and home heating. Fortunately for the residents of Great Britain there were surface coal seems in abundance making the transition relatively easy; once these were exhausted deep mining followed which at last, by the late 1600s, created the demand for coal-powered pumps, finally answered effectively in 1712 by Newcomen: a demand for engines to power pumps in an environment where fuel efficiency mattered little.

With an end use case in place, these early steam engines continue to be refined to make them more powerful, more fuel efficient and capable of producing smooth rotational motion out of their initially jerky reciprocal motions, culminating in James Watt’s steam engine in 1776. But so far all we’ve done is become very good at pumping out coal mines – that has in turn created steam engines that are now fuel efficient enough to be set up in places that are not coal mines, but we still need something for those engines to do to encourage further development. In particular we need a part of the economy where getting a lot of rotational motion is the major production bottleneck.

Above is a photograph of a late version of Watt’s final steam engine design. Watt made a number of improvements to the Newcomen engine, adding a separate condenser to allow the cylinder itself to remain hot, including a vacuum jacket around it to limit the energy loss and eventually introducing a double-action where the piston was pushed by steam pressure in both directions, enabling a stronger and smoother stroke, along with gearing that allowed the reciprocal motion of the piston to be translated into the rotational motion necessary for most tasks.

You may be thinking that agriculture and milling grain is the answer here but with watermills and windmills, the bottleneck on grain production is farming, not milling. The answer is the other half of the traditional agrarian economy: textiles. The major production bottleneck, consuming 80% or more of the time intensity of textile production (not including fiber production), is spinning the fibers into thread – a process which relies on lots of rotational motion. And indeed, in the 1700s, further improvements in looms (the flying shuttle) had intensified this bottleneck by making weaving progressively more efficient.

Through the Middle Ages, the movement of wool textiles was one of the most important trade systems in Europe. Great Britain was the major center of textile production for much of the world. Wool produced in Scotland and Wales was moved to England where it was turned into thread and then cloth and then sent to the Low Countries to be dyed before using Europe’s river systems to reach consumers all over the world. European imperialism had only intensified this system because British conquests in India had directed massive amounts of cotton into this same system alongside the wool.

But there is another key step necessary here: the steam engine produces rotational motion and the spinning process requires rotational motion but you also need a machine capable of turning lots of rotational motion into real efficiency gains for spinning. Prior to the 1760s, no such machine really existed. Since the Middle Ages you had the spinning wheel, but applying a lot of energy to a spinning wheel isn’t going to help – the spinner is still only managing a single thread. Still the pressure to produce spinning technology that could match the efficiency gains of the flying shuttle was on and in 1765 it resulted in the spinning jenny, developed by James Hargreaves. The spinning jenny allowed a single spinner to manage multiple spools at once using a hand-crank. Unlike the spinning wheel, which could be a household tool (and thus before 1765, most spinning was still literally ‘cottage’ industry, farmed out too many, many spinners each working in their homes), the spinning jenny was primarily suited for commercial production in a centralized location (where the expensive and not at all portable spinning jennies were). The main limit on the design was the power that a human could provide with the hand-crank.

Above is an illustration of a spinning jenny, with a hand crank that can be used to turn multiple spools at once, multiplying the efficiency of the spinner.

And now, at last, the pieces are in place and the revolution in production arrives. There is a machine (the spinning jenny) which needs more power in rotational motion and already encourages the machines to be centralized into a single location; the design is such that in theory one could put an infinite number of spools in a line if you had sufficient rotational energy to spin them all. Realizing this, textile manufacturers first used watermills, but there are only so many places in Great Britain suitable for a watermill and a windmill won’t do – the power needs to be steady and regular. But the developments of increasingly efficient steam engines used in the coal mines now collide with the developments in textiles: a sophisticated steam engine like the Watt engine could provide steady, smooth rotational motion in arbitrary, effectively infinite amounts (just keep adding engines!) to run an equally arbitrary, effectively infinite amount of mechanical spinning jennies, managed now by a workforce a fraction of a size of what would have once been necessary.

Below is a photograph showing how many spinning ‘mules’ could be connected via an overhead shaft to a single large source of rotational motion, like a steam engine, allowing truly massive amounts of thread to be spun at once by a much smaller work force. The work could be dangerous as there were few safety systems in place.

The tremendous economic opportunity this created in turn incentivized the production of better steam engines and the application of those engines to other kinds of production; there is a whole additional story of how the development of the steam engine interacts with the development of new artillery-production methods (both relying on the production of strong, standardized pressure-containing cylinders). All of those end use cases push steam engines to become smaller, more fuel efficient and more powerful, which in turn increases the number of tasks they can be put to. Eventually in the 1800s, these engines get small enough and fuel efficient enough to be able to move their own fuel over water or rails, collapsing the prohibitive transportation costs that defined pre-industrial economies.

But the technology could not jump straight to railroads and steam ships because the first steam engines were nowhere near that powerful or efficient: creating steam engines that could drive trains and ships (and thus could move themselves) requires decades of development where existing technology and economic needs created very valuable niches for the technology at each stage. It is particularly remarkable here how much of these conditions are unique to Britain: it has to be coal; coal has to have massive economic demand (to create the demand for pumping water out of coal mines) and then there needs to be massive demand for spinning (so you need a huge textile export industry fuelled both by domestic wool production and the cotton spoils of empire) and a device to manage the conversion of rotational energy into spun thread.

So Why Not in Rome?

Understanding why these processes did not happen in the Roman world is actually quite easy: none of these precursors were in place. The Romans made some use of mineral coal as a heating element or fuel, but it was decidedly secondary to their use of wood and where necessary charcoal. The Romans used rotational energy via watermills to mill grain, but not to spin thread. Even if they had the spinning wheel (and they didn’t; they’re still spinning with drop spindles), the standard Mediterranean period loom was roughly an order of magnitude less efficient than the flying shuttle loom, so the Roman economy couldn’t have handled all of the thread the spinning wheel could produce.

The Romans had put no effort into figuring out how to make efficient pressure-cylinders, because they had absolutely no use for them. By the time Newcomen is designing his steam engine, the kings and parliaments of Europe have been obsessed with who could build the best pressure-cylinder (and then plug it at one end, making a cannon) for three centuries because success in war depended in part on having the best cannon. If you had given the Romans the designs for a Newcomen steam engine, they couldn’t have built it without developing whole new technologies for the purpose.

Technologies are contingent and path dependent. The industrial revolution only happened once in one place, could it have happened somewhere else in a different way with different preconditions; we’ll never really know because our one industrial revolution spread over the whole globe before any other industrial revolutions happened. But we can still note that the required precursors for the one sample we have didn’t exist in the Roman economy.

But then that raises, I think, another question with how we think about economies in the past: if it wasn’t on the cusp of a revolution, what made the Roman economy unusual?

The Nature of the Roman Economy

Broadly speaking human production fits into three major types: non-agrarian hunter-gatherer societies, agrarian and pastoral societies, and finally industrial societies. The first merely harvests what the environment already provides, while agrarian and pastoral societies actively reshape local ecology to make it provide more. Both are ‘organic’ economies in that nearly all of the energy they use is provided by muscle power. Industrial economies derive the majority of the energy they use from sources other than muscle power, eg fossil fuels, nuclear power, solar, etc.

The Roman economy was remarkably productive for an organic economy. The Roman Empire as a result of its conquests created a linguistic, customs and monetary union over the whole Mediterranean, which was kept relatively free of things like pirates and bandits. Each of these changes made markets more reliable and efficient, which in turn could mean that a larger proportion of farmers could specialize their farming output resulting in higher total output. That greater output then enables the economy to support more specialized workers with high productivity making non-agricultural goods which thus become more common and eventually affordable

Second, the interconnectedness the Roman Empire encouraged the spread of innovations in production, both agricultural and non-agricultural, things like watermills for the grinding of grain, new more effective presses for olives, higher quality metal working and so on. These technologies were not revolutionary but evolutionary and often what was changing was not their existence but their distribution: ideas that had been ‘stuck’ in one corner or other of the empire can suddenly spread out over those more interconnected lines of trade.

Finally the relative stability and peace the Roman Empire created within its borders makes it more sensible to invest in things like new mills or presses which need to be used for a while for the small efficiency gains to outweigh the cost of putting them up.

But the key here is that none of these processes inches this system closer to the key sets of conditions that formed the foundation of the industrial revolution. Instead, they are all about wringing efficiencies out the same set of organic energy sources with small admixtures of hydro- (watermills) or wind-power (sailing ships); mostly wringing more production out of the same set of energy inputs rather than adding new energy inputs. It is a more efficient organic economy, but still an organic economy, no closer to being an industrial economy for its efficiency, much like how realizing design efficiencies in an (unmotorized) bicycle does not bring it any closer to being a motorcycle; you are still stuck with the limits of the energy that can be applied by two legs.

As a result, the ingredients for the ‘take-off’ of the industrial revolution (which involves adding more energy to the economy on a per capita basis) aren’t there. In my view the key takeaway here is just how contingent the industrial revolution was: the industrial revolution that occurred required a number of very specific pre-conditions which were really only true in Great Britain in that period. It is not clear to me that there is a plausible and equally viable alternative path from an organic economy to an industrial one that doesn’t initially use coal (much easier to gather in large quantities and process for use than other fossil fuels) and which does not gain traction by transforming textile production which was a huge portion of non-agricultural production in organic economies.

Much of history has been contingent on unpredictable variables. If Spain or Portugal, for instance, rather than Britain, had ended up controlling India, would the flow of cotton have been diverted to places where coal usage was not common, cheap and abundant, thereby separating the early steam-powered mine pumps from the industry they could revolutionize. This question, like so many counter-factuals, is fundamentally unanswerable but useful for illustrating the deeply contingent nature of historical events.