Why no Roman industrial revolution?

In my last post I repeated Marx’s phrase the the hand mill gave you the feudal lord the steam mill the industrial capitalist. One reader objected that this overstated the role of technology and that steam power was already known to the Romans. I concede that Marx over simplified. There were thousands of water mills in England recorded in the Domesday book. So ownership of water mills was a key part of the power of the feudal lords. A better phrase would have been that the water mill brings you the feudal lord the steam mill the industrial capitalist. But to return to the original question.

The ancient Romans already had a working steam turbine in Hero’s aeolipile. Why were they not able to turn this to use in industry, pumping water or turning millstones?

Why no industrial revolution in antiquity?

There are well known arguments about the social relations of slavery impeding the development of labour saving technology, but is this enough of an explanation?

We know that the ancients harnessed the power of water for grinding corn and other industrial uses, so they were not completely indifferent to artificial sources of power.

Could they not have used steam turbines instead of water wheels to grind corn?

There are the obvious objections that the Mediterranean basin has no coal deposits to fuel steam engines. But in due course they had conquered Northern Gaul and Britannia where they were able to extract coal. Could they have set up and industrial economy in these areas?


Figure 1: Hero’s turbine, or aeolipile reproduced from [1].

I think not. There are inherent technical limitations to the usefulness of Hero’s device, basically its low torque and inefficiency. Steam turbines are now the preferred prime mover – in use in fossil and nuclear power stations across the world, but their superiority has depended on the ability to produce high pressure steam and high rotational velocity. The actual technology that started the industrial revolution – the Watt steam engine had the virtues that it could develop very high torques at low velocity using very low steam pressures.

In order to get a functioning fossil fuel economy you had to have a prime mover and a way of providing fuel for it. The main fuel available was coal which was obtained from mines prone to flooding. The Watt engine was originally developed for pumping out mines, an application which required a lot of force but tolerated a relatively slow engine. The torque T supplied by a Hero style turbine is given by the rule

T = p × 2a × r

whee p is the steam pressure, a the area of each exhaust nozzle and r the radius of the turbine.

The torque provided by a Watt beam engine was given by a similar rule

T = p × a × l

where p is now the pressure difference between the boiler and the condenser, a the area of the cylinder and l is the beam length.

The early Watt engines were huge, with beam lengths of over 3 meters compared to the few centimeters for the length of hero turbines. This is a factor of 100 difference. In terms of diameter of bore a practical Hero turbine would not have exceeded 1 cm against half a meter for a Watt engine. This is a factor of about 2500 greater area for the Watt machine. Let us assume both operate at the same steam pressure, since the technology of boiler construction was initially the limiting factor. That means that the torque of an early Watt engine was about a quarter of a million times greater than an aeolipile.

Could you build an aeolipile that generated comparable torque?

Well yes if you had arms a couple of meters long on the turbine and nozzles a half a meter in diameter, then the torque would be comparable. But the nozzles of the aeolipile are open to the air, so a nozzle half a meter across would use up an entirely impractical quantity of steam.


Figure 2: Laval’s first turbine used to power a cream centrifuge in 1884. It used a simple modification of Hero’s turbine in concept, but relied on precision engineering and high pressure steam.

An aeolipile is only practical as a power generating device if the revolutions per second are very high. A small torque multiplied by a very high number of revs per second can generate a useful amount of power.

The aeolipile had to go through a series of of steps before it could be converted, in the 1880s into practical turbines by Laval and Parson. The first practical use of of a reaction turbine was for Laval’s cream separator. This required very rapid rotation, around 1000rpm, to centrifugally separate cream from milk, so a high speed device was desirable. Laval’s first prototype was based on the aeolipile but heavily geared down using friction gear to get it down to 1000rpm. His second prototype switched to the impulse principle – directing a jet of high pressure steam against a rotating set of turbine blades.

Rotation speeds were very high the 300hp turbine in Table 1 had a peripheral velocity of 366M/s or 1317Kmph – supersonic velocity.

Table 1: The performance of production Laval turbines of the late 19th century. Data from [1]

Horse Power Radius Revs per min of turbine Revs per min of geared output

5 5cm 30,000 3,000

30 11cm 20,000 2,000

300 35cm 10,000 750


Figure 3: Laval’s second turbine 1886 switched to the impulse principle and went into practical production.

Between the start of steam power and the first practical use of a reaction turbine over 100 years elapsed, during which many engineers came up with suggestions for turbines. But it was not until the 1880s that Parson and Laval designs actual got into use. They depended on having high pressure steam, precision engineering and high strength steels to work. None of these were available to the Romans. They did not have the blast furnaces and forges necessary to make the wrought iron for boilers, far less the Bessemer converters to produce the steel for turbine blades. Steam turbines only became practical as a source of power once industrial society was in full swing.

Well even if turbines were not practical, what stopped the Romans building something like one of Watt’s engines?


Figure 4: The demonstration of atmospheric pressure by Guericke who pumped the air out between two copper hemispheres and demonstrated that even two teams of horses could not pull them appart. This experiment was a key to the development of atmospheric engines like those of Watt.

Basically a lack of scientific knowledge. The Watt engine depended for its power stroke on atmospheric pressure. Steam was supplied at near atmospheric pressure, and then condensed to create a vacuum. That depended in turn on two key prior concepts – the discovery of atmospheric pressure by Torricelli, and the concept of heat as a quantity to be conserved developed by Watt’s supervisor at Glasgow Prof. Black.

Technologies have an order of dependence to them that can not be arbitrarily skipped over. Without the knowledge and skills associated with a particular stage of technology, you can not simply go on to develop the next.


[1]   Alexander Jude. The Theory of the Steam Turbine. Griffin and Company, 1910.



  1. The question of why there was no Roman industrial Revolution is I believe a false one. Certainly the predominance of slave labour as an explanation is a red herring. As soon as one examines the reasons for the Industrial Revolution in Britain, one can readily appreciate that there could not have been one in Ancient Rome, and not only for the reasons that Paul elucidates.

    The earliest reference to the production of coal in the British Isles, I believe, is 1291, when the Lord of Pittencrieff grants to the Abbot and monks of Dunfermline Abbey the right to dig for coal on his land ”provided they do not presume to sell it and only for their own use.”

    In the 16th century the later Pope Pius II on visiting Scotland noted that Fife was almost denuded of wood and that poor people were happy to receive ‘a black stone’ as alms at the church doors. In the same century the export of coal from Scotland was at one time prohibited, due to fears of its excessive consumption.

    Yet, though coal and iron were available so early, it was not till 1759 that the great Carron Ironworks were established, using for the first time in Scotland pit coal to smelt iron. By the beginning of the 19th century these were the biggest ironworks in Europe, employing more than 2000 men.

    A number of factors came together to allow of this: plentiful local coal and iron ore, the site on the river Carron for water supply, the ability to import timber by sea, the possible purchase of technology and skilled labour from England, a ready supply of local wage labourers, and sufficient accumulation of capital to fund it all (one of the capitalists for example was a rich merchant who had made his fortune in foreign trade), and a rising demand and consequently high price for good quality iron.

    We see then that a complex of factors, economic, social and geological, explain Britain as the home of the Industrial Revolution, and these are absent in Ancient Rome. Marx explains it very well in Vol I of Capital. What then does he mean by ”the hand mill gives you the feudal lord, the steam mill the industrial capitalist”? Bourgeois critics cite this passage as an example of Marx’s ‘technological determinism.’ I rather suspect that Marx was writing in French but thinking in German. Take the German phrase ‘Morgen gibt es in Berlin Regen.’ This means that tomorrow in Berlin you will find it is raining. So I think Marx’s meaning is that where you find the predominance of the hand-mill you will find the feudal system, where that of the steam engine the capitalist system. In no way does he mean that the steam engine causes or gives rise to the capitalist mode of production. The means of production determine the relations of production, but the relations of production determine the means of production. That is I believe the point of departure in understanding why the invention of the steam engine could not become a means of production for the ancients, i. e. it was not appropriate to the the level of their economic development: determinatio est negatio.


  2. This is a very good argument. My only objection is the assertion that the Romans lacked the scientific knowledge to build a steam engine like Watt’s. We simply do not know that to be the case. So, much ancient knowledge has been lost it is impossible to properly gauge just what they knew. Even if Hero’s steam engine was not practical for industrial applications. It does point to there being a great deal of scientific curiosity in Alexandria. I also wonder what impact patenting has had on the development of technology. To my knowledge there was no system of patenting in the ancient world. Does patenting help or hinder technological development? Does the lack of patenting incentivise secrecy? Did the legal framework of patenting play a role in Watts development of the steam engine? Was it this lack of legal framework that really stopped the Romans for having an industrial revolution? They lacked the legal tools to make it happen.


  3. ”Was it this lack of legal framework that really stopped the Romans for having an industrial revolution?” Jay asks. No, I rather think it was more a lack of double-entry bookkeeping.

    As for the scientific knowledge, Paul is correct. Even if the ancients appreciated the principles of steam power, they lacked the metallurgical knowledge to construct one like Watt’s.


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