Southerly by David Haywood

This is a transcript of an episode of Public Address Science which was originally broadcast on Radio Live, 17th November 2007, 5 pm - 6 pm.

You can listen to the original audio version of the programme by clicking on the 'Play the audio for this post' link at the top of this page or the 'Audio' button at the bottom of this page.

Background:

[Sound of singing at 'The Last Night of the Proms']

Voiceover:

Along with athlete's foot and haemorrhoids, one of the most annoying things you may ever experience is the horrible noise you're hearing right now -- also known as "The Last Night of the Proms". The sound of embarrassing British patriotism is akin to the howling of dogs as far as I'm concerned -- but what makes it even more deeply irritating is the special pride-of-place given to the rather good song that they're murdering as I speak: Jerusalem.

Rather mysteriously, the flag-waving English are clearly of the opinion that Jerusalem is a patriotic hymn -- although even a cursory glance over the lyrics reveals that this is not the case. In fact, it would perhaps be more accurate to describe Jerusalem as an environmental protest song: perhaps the first environmental protest song ever written.

The author of the original poem, William Blake, was railing against the industrialization of the English landscape and populace [1][2]. The dark satanic mills that these sheep-like Englishmen are singing so cheerfully about, aren't in any way metaphorical -- but rather the very real sulphur-belching cotton mills and paper mills that had resulted from the British exploitation of energy from coal.

Background:

[Sound of wind over high-tension power lines]

Voiceover:

In last week's episode, I talked about the way in which the chemical energy from coal was first employed to produce useful work in the context of pumping water from coal mines. In the subsequent decades, an improved version of this engine -- redesigned in 1765 by James Watt [3] -- began to be employed to provide useful work in other industrial situations. For factories, in particular, this was a Godsend. No longer were they dependent on sites with favourable wind and flowing water

to provide energy: factories could now be located for easy transportation of goods via canal or sea, or for proximity to existing populations of potential workers.

Background:

[Sound of spinning machine]

Voiceover:

And the increases in productivity were remarkable. To give but one example: hand-spun cotton in the early 1700s required more than 1,100 hours of labour to produce a single kilogram of yarn -- but, by 1825, it took only three hours of labour to produce the same amount using a machine (only 1/370th of the previous labour cost) [4].

Unfortunately, by modern standards, the conditions for most of the workers in these new factories can only be described as horrific. With a few notable exceptions the hours were long, the working environment was appalling, the pay was minuscule [5], and severe injuries (and even fatalities) were commonplace [6]. Children as young as seven were employed -- working as much as thirteen hours per day [7]. And the sulphurous smoke and pollution produced by these factories fully justified the description of "dark [and] satanic".

Background:

[Sound of steam engine]

Voiceover:

One of the contributory factors to these acrid fumes was the incredibly low efficiency of the early steam engines. Although Watt's engine was major improvement over its predecessors, its efficiency was still only 4.5 per cent [8]. Each joule of useful work that it produced required an input of 22 joules of chemical energy from coal. And this meant that vast amounts of coal had to be burnt in order to provide comparatively modest amounts of useful work.

So why was engine efficiency so low? Well, the short answer is that science hadn't caught up with the advances in engineering. The early engines weren't energy-efficient because -- in a scientific sense -- energy hadn't actually been discovered yet. In

fact, no-one had even realized that work and heat were both manifestations of the same thing. They were even measured in entirely different units: heat in something called British Thermal Units (or BTUs), and mechanical work in units of foot-pound-force.

Background:

[Sound of stirrer in bucket of water]

Voiceover:

It wasn't until the mid-1800s that the equivalence of heat and work was demonstrated by an English scientist called James Prescott Joule [9]. His apparatus is so simple that nowadays it could be duplicated in anyone's backyard shed. It simply consists of a known weight attached to a rope -- which, in turn, is attached (via a pulley system) to a stirrer in an insulated bucket of water. As the weight is dropped, the stirrer rotates, and stirs the water in the bucket.

What Joule was able to show with his experiment was that the work done by the falling weight in stirring the bucket of water didn't just vanish into the aether -- but was actually transformed into thermal energy, which stayed within the insulated bucket and raised the temperature of the water.

Background:

[Sound of steam engine]

Voiceover:

Joule had shown that [in the normal scheme of things] the "ability to do work" (or 'energy' as it's now called) is not actually something that can be created or destroyed -- merely transformed from one form to another. This means, for example, that the chemical energy from coal is not 'used up' when it is burnt in a steam engine, but merely transformed into other forms of energy: a small amount into useful work, but most of it into heat or thermal energy -- either going up the smokestack as hot exhaust gas, or rejected into the cooling water. A portion of the original coal energy is even transformed into

the acoustic energy that our ears detect as sound.

This was such an important scientific revelation that Joule was honoured by having the measurement unit of energy named after him, and his findings were immortalized as the First Law of Thermodynamics [10] (where 'thermo' refers to heat; and 'dynamic' refers to work). It was the final nail in the coffin for machines that claimed to be able to create energy from nowhere (otherwise known as perpetual motion machines of the first kind). And, for the first time, it gave the means for engineers to calculate just how lousy their engines actually were -- as they made the comparison between heat input to a steam engine and the useful work output.

Background:

[Sound of wind over high-tension power lines]

Voiceover:

But here's an interesting question: from Joule's discoveries about energy it would seem perfectly reasonable to conclude -- as some nineteenth century engineers did -- that the maximum achievable efficiency for a coal-powered steam engine should be close to 100 per cent. After all, if heat and work are equivalent forms of energy then (allowing for a few minor losses) nearly all of the heat obtained from burning coal should be able to be converted into useful work in a well-designed engine. Shouldn't it?

Well, no, actually. Joule's discovery shed light on earlier work by a French engineer, Sadi Carnot. Carnot had speculated that there was an upper limit to the efficiency of engines. This theory of his 'Carnot limit' was further developed by Joule, and one of Joule's collaborators, William Thomson (who later became Lord Kelvin) -- as well as the
German mathematician and physicist, Rudolf Clausius [11]. And eventually this became known as the Kelvin-Planck statement of the Second Law of Thermodynamics [12].

Background:

[Sound of running water]

Voiceover:

To understand -- in simplistic terms -- why this Second Law of Thermodynamics means that an engine can never be 100 per cent efficient, you have consider the fact that all heat engines require a working fluid. This is the substance inside the engine which is heated by burning the fuel, and which produces a work output -- usually by 'pushing' on a piston or a turbine. In a steam engine the working fluid is steam and water; in a car engine or a jet engine, the working fluid is air.

As an engine performs the process whereby heat is transformed into work, then the temperature of the working fluid is reduced. And in order for an engine to transform all of the input heat energy into useful work, then the temperature of the working fluid would have to be reduced to the point at which all molecular motion ceases: a temperature of exactly -273.15 degrees Celsius.

Background:

[Sound of wind over high-tension power lines]

Voiceover:

Now there are obvious practical objections to running part of an engine at this sort of temperature. But, even apart from this, the coldest known naturally-occurring temperature is found in interstellar space -- at 'only' -270 degrees Celsius [13] -- still three degrees short of the temperature that the working fluid in an engine would have to reach in order to fully convert heat into work. In fact, there are theoretical reasons to think that such a temperature can never be reached -- a theory, by the way, known as the Third Law of Thermodynamics.

Because we live on a nice warm planet, the minimum temperature that the working fluid in an engine can reach is, well... just above room temperature. In other words, about 300 degrees Celsius above the temperature needed to fully

convert heat into work. Given the high-temperature constraints on engine materials, this means that the maximum efficiency that can be reached for an engine -- even in theory -- is only around 70 per cent.

Background:

[Sound of a steam whistle]

Voiceover:

The discovery of the first and second Laws of Thermodynamics was something of a good news/bad news story for 19th century engineers. The bad news was that their engines were horribly inefficient; the good news was that the inefficiency wasn't quite as bad as it looked because, in practice, the maximum theoretical efficiency of a heat engine is a lot less than 100 per cent.

Background:

[Sound of a diesel engine]

Voiceover:

And, I suppose, the other good news was that the Laws of Thermodynamics gave engineers some very good information about how to improve the efficiency of their engines. In the late 1800s, this culminated in a machine designed by a German engineer called Rudolf Diesel.

Diesel was a university-educated engineer who set out to design an engine according to thermodynamic principles so that it would attain very high efficiency [14]. His early attempts to fuel his engine with coal-dust were failures, but he finally achieved success when he used a relatively new engine fuel called 'oil' [15]. Diesel's invention would eventually supplant the steam engine in most applications, including ships and the machine that revolutionized transportation in the 1800s -- the train.

But more on that next week...

Further information on this episode:

• Read about the Laws of Thermodynamics in Wikipedia.
  
  
Read about the Diesel engine in Wikipedia.

This is a transcript of an episode of Public Address Science which was originally broadcast on Radio Live, 3rd November 2007, 5 pm - 6 pm.

You can listen to the original audio version of the programme by clicking on the 'Play the audio for this post' link at the top of this page or the 'Audio' button at the bottom of this page.

Background:

[Sound of narrow-boat on canal]

Voiceover:

Is there any journey more pleasant than a trip through the English countryside by canal? In my opinion, the canal boat or -- [more] properly -- the narrow-boat, is perhaps the most pleasant form of transportation ever invented.

The design of a narrow-boat is aesthetically-pleasing -- nice bright paintwork with the traditional brass hoops around the chimney. And a narrow-boat travels at just the right speed: any faster and you'd miss the sights; any slower and you'd never get there. You can stand out on deck, and quite literally smell the flowers as they go past. The only conceivable improvement would be some sort of on-board brewery -- so that you'd never have a reason to leave.

In fact, canals and narrow-boating have become so synonymous with pleasure cruises, that it's almost a surprise to recall that canal technology represented nothing less than a revolution in terms of the efficient use of energy for transportation.

Background:

[Sound of wind over high-tension power lines]

Voiceover:

In last week's episode, we saw how the timber famine in England led to the widespread use of coal as fuel. Not only for heating -- but also as a replacement for wood fuel in the manufacture of iron, glass, and bricks.

But hand-in-hand with the growing use of coal came the need for efficient transportation [of coal]. The appalling quality of roads in England (and Europe in general) up until the eighteenth century, meant that inland transportation to bring -- for instance -- coal and iron ore together for smelting was prohibitively expensive [1].

Background:

[Sound of horse and cart]

Voiceover:

In 1750, it took what was described as "innumerable relays" of 22-oxen teams a minimum of two years to transport heavy oak logs for shipbuilding from the

forests of Kent to the Chatham naval yard on the Thames. Yes -- you did hear correctly -- that's two years to carry the logs a distance of about 80 kilometres [2].

Subsequent improvements in road quality greatly increased the efficiency of British roads in terms of both time and energy; but even on the highest-quality Telford roads built from 1750 onwards, a single horse could only haul about two tonnes. That same horse -- when walking on the tow-path of a quiet river -- could pull a boat load of 50 tonnes [2].

Background:

[Sound of horse and cart]

Voiceover:

Of course, canals for transportation were hardly a British invention -- the Persians dug a shipping canal to join the Red Sea and the Mediterranean in around 500 BC [3] -- and canals were constructed all over Europe. But England (and the British Isles in general) had several features that made transportation canals particularly suitable.

Firstly, the English countryside is rather flat and low-lying in comparison to, say, Switzerland or Austria, thus making canal construction relatively straightforward. Secondly, the appalling English weather means that the waterways almost never run dry -- unlike Spain or Portugal where water shortages are a problem in summer [4][5]. Thirdly, the comparatively mild island climate means that during the winter the waterways seldom freeze as they do in Scandinavia or Russia. And, fourthly, by the 1700s the English timber famine had resulted in a need for the transportation of coal on a very large scale, thus making canal construction a potentially profitable enterprise -- even over the short term.

Background:

[Sound of pick and shovel]

Voiceover:

In 1761, the Duke of Bridgewater (or, rather, his labourers) completed the first British canal, which connected the coal mines on his estate to the city of Manchester.

The remarkable efficiency gains in terms of transport energy meant that the Duke was able to provide the millowners in Manchester with the cheapest coal in England -- while, at the same time, paying back his investment in just a couple of years, and providing an absolutely colossal income for himself thereafter [2].

The potential for such vast profits encouraged further canal construction -- and a remarkable example of the positive feedback loop. It worked like this:

• the gains in transport energy efficiency from canals reduced the price of coal
• which, in turn, reduced the price of manufactured goods
• which, in turn, meant that more goods were sold
• which, in turn, meant that more coal was needed to manufacture more goods
• which, in turn, meant that more canals were needed to ship more coal from more coal mines.

So the very act of building canals created the demand for even more canals -- and, of course, lots and lots more coal.

Background:

[Sound of wind over high-tension power lines]

Voiceover:

The synergy that resulted from the combination of energy (and energy efficiency) from canals and coal was of critical importance. And this is aptly demonstrated by the example of China -- which, as I explained in last week's episode, was far more technologically advanced than any Western European country throughout the medieval period.

Now, of course, in the post-medieval period, European countries such as Britain developed extensive overseas empires -- but, even so, China (a huge country) still had vast wealth: both in terms of natural resources and population. And China had coal, too. But unlike Britain, China's coal was in very remote inland locations from which it could only be transported with great difficulty. Although China had possessed canals for centuries, there was no equivalent to the network of canals that linked British coal mines, British factories, and British population centres [6].

Background:

[Sound of narrow-boat on canal]

Voiceover:

The impact of canals and coal is perhaps best illustrated with a snapshot of the beginning and end of the century between 1750 and 1850. I began last week's episode in the year 1066, when the population of England was around one million people [7]. In the seven hundred-odd years between 1066 and 1750 the population of England grew by around four and a half million. But in a single century of coal and canals following 1750, the English population grew by eleven million people [8].

Background:

[Sound of industrial machinery]

Voiceover:

The productivity gains which paid for this extra population -- and which, I would argue, was a direct consequence of the removal of the energy constraints associated with using wood as a fuel -- totally transformed the British economy. In 1750, England was an agrarian country with the majority of the population directly employed in agriculture. But by the British census of 1851, only a fifth of the workforce were employed in agriculture, forestry, and fishing combined; and nearly half the working population was now employed in industry, manufacturing, and mining [9].

Shortly after 1850, at the height of [relative] British industrial power, this tiny nation produced more than half of the world's iron and steel; about half of the world's coal and cotton goods; and, additionally, it possessed more than a third of the world's merchant navy [10].

Voiceover:

But, of course, using coal as an energy source was not without its issues. You probably don't have to do much more hewing with coal than with wood, but you certainly have to do a lot more digging. And, of course, as you dig deeper -- and as I'm uncomfortably aware of now, as I stand at the bottom a mine shaft -- you have the very real possibility that everything will suddenly fill up with water.

Background:

[Sound of pick and shovel]

Voiceover:

As more coal was required -- and mines got deeper -- then flooding became a major problem. Energy from animals and waterwheels was exploited to operate pumps, but this proved to be extremely expensive. And then, in 1698, an English inventor called Thomas Savery had the brilliant idea to use the energy from coal itself to pump water [11].

This was the moment when everything changed. In the whole of human history, energy from a fossil fuel had never before been used to produce useful work in this sort of industrial context. It's no exaggeration to say that -- in a single stroke -- Savery not only invented the first industrial engine, but also modern civilization.

Background:

[Sound of steam engine]

Voiceover:

From a technical viewpoint, however, Savery went about designing his coal-powered pump in the most backwards way possible. Although it really did work to pump water from coal mines, it had numerous shortcomings -- not least that it's efficiency was only a fraction of a per cent [12].

It took an English blacksmith, Thomas Newcomen, in 1710 to turn Savery's idea inside-out and dramatically improve its thermal efficiency -- to around half a per cent [13]. While this represented an enormous advance over the original Savery pump, it was still nothing to write home about in efficiency terms: every joule of useful work that the pump
provided required 200 joules of chemical energy from coal. Colliery owners complained that they needed a separate coal mine just to keep their Newcomen engines running.

Background:

[Sound of pipe band]

Voiceover:

Perhaps predictably, it was a penny-pinching Scotsman, James Watt, who redeveloped the Newcomen engine into a practical machine -- and increased the efficiency more than five fold [to 2.7 per cent] [13]. Watt's design is recognizably the ancestor to all modern reciprocating steam engines, and by the 1790s more than a thousand of Watt's pumps were in operation in British coal mines [14]. Furthermore, the design was so successful that it began to be used to run flour and corn mills; hoists, cranes, and industrial fans; paper and cotton mills; and the machinery in iron works [15]. The age of industrial steam power had arrived.

Background:

[Sound of steam engine]

Voiceover:

Now all through this series, I've been blithely talking about energy and energy efficiency -- but, in fact, the idea of energy "the ability to do useful work" wasn't actually figured out until the mid-1800s [16][17]. In next week's episode we'll be looking at the great nineteenth century advances in the science of heat and work (or 'thermodynamics') -- and to something that's perhaps the key factor to understanding the way that energy works in the world: the Laws of Thermodynamics.

Further information on this episode:

• Read about Savery's pump in Wikipedia.
  
  
• Read about Newcomen's engine in Wikipedia.
  
  
Read about the Watt steam engine in Wikipedia.

This is a transcript of an episode of Public Address Science which was originally broadcast on Radio Live, 13th October 2007, 5 pm - 6 pm.

You can listen to the original audio version of the programme by clicking on the 'Play the audio for this post' link at the top of this page or the 'Audio' button at the bottom of this page.

Background:

[Sound of swords clashing and medieval soldiers shouting]

Voiceover:

This is what it might have sounded like at Hastings in East Sussex on the 14th of October, 1066 -- the day when the army of the invading William, Duke of Normandy, killed King Harold II and conquered England. In fact, what you hear right now is a modern re-enactment of the Battle of Hastings conducted by under-employed history enthusiasts.

As we all know, events turned out badly for the English on that day in 1066. But William's victory resulted in two very useful historical documents, which provide a fascinating snapshot of energy usage at the mid-point (more-or-less) of the Middle Ages. Firstly, the Bayeux Tapestry, essentially a comic-strip embroidery version of the story of the Norman Conquest. And, secondly, the Domesday book -- the inventory of England conducted by William the Conqueror (as he became known) in order to gauge the value of his conquests for tax purposes.

Background:

[Sound of wind over high-tension power lines]

Voiceover:

In last week's episode, we visited the city of Alexandria in 150 AD -- at that time, the intellectual centre of the ancient world. And in Alexandria we discovered that (although the exploitation of energy had allowed a great civilization to flourish) the enormously inefficient way that, for example, wind energy and animal labour were used, meant that the predominant energy source for performing useful work -- such as milling grain, pumping water from metal mines, or propelling ships against the wind -- was still human labour.

Background:

[Sound of swords clashing and medieval soldiers shouting]

Voiceover:

But a millennium or so later the situation had radically changed. Although, as a country, England was practically the middle of nowhere -- part of a rather obscure former Roman province -- even here the

technology for exploiting energy would put the ancient world to shame.

Background:

[Sound of horse and cart]

Voiceover:

The Bayeux tapestry clearly shows that English horses wore horse-collars at the time of the Norman conquest [1]. For the same amount of food, the medieval horse-collar allowed a horse to pull about four times more than if it were wearing a primitive Roman harness [2] -- and this meant that by the middle of the Middle Ages, even in a technological backwater like England, it made a lot more sense to use horse-power rather than human-power.

Background:

[Sound of water wheel]

Voiceover:

And what about those Roman grain mills, driven by slaves running around in enormous human-sized hamster wheels? Well, shortly after the Norman conquest, the Domesday Book records that there were 5,624 mills in England powered by water wheels [3]. That's at least one water-powered mill for every 180 people in the country [3]. It's conceivable that, just by themselves, these water mills (in comparison to human-powered mills) could have freed-up the labour of perhaps 15,000 men -- about one-and-a-half per cent of the English population at that time.

Background:

[Sound of waves and seabirds]

Voiceover:

And what about developments in wind energy? Windmills and wind-pumps wouldn't become part of the English landscape for another century (although they had been widely used in the Middle East since before 950 AD) [4], but some of the ships visiting the English shores did harness wind energy in an improved way -- using a very different approach to the sea-going vessels in the harbour of Alexandria in 150 AD.

These were the Viking ships -- which, incidentally, King Harold II knew all about, because he'd had the very bad luck to have fought off a Viking invasion fleet just two days before the

Norman invasion fleet arrived at the coast of England in 1066 [5].

Background:

[Sound of wind over high-tension power lines]

Voiceover:

Of course, according to some modern historians, Vikings have been unfairly treated by the history books. It's now claimed that they voyaged not in order to murder and pillage, but to form poetry appreciation societies, and to help people in other countries 'get in touch with their feelings' [6]. Whatever the truth of the matter, the Vikings owed a large portion of their success to their ships, which along with several other important innovations, used a device called a Beitiáss or 'tacking spar' to generate lift from square sails [7], and (in contrast to the vessels of the ancient world) to travel against the wind [8]. This much more effective exploitation of wind energy allowed the Vikings to kick up bobsy-die all around Europe, to settle Iceland and Greenland, and even to reach North America [9].

Background:

[Sound of waves and seabirds]

Voiceover:

But the Viking efforts at settlement were peanuts compared to that of the Austronesian voyagers. The Austronesians and their descendents (including, among others, the Polynesians) eventually settled an area that stretched seven-and-a-half thousand kilometres from Hawaii in the North to New Zealand in the South; and eighteen-and-a-half thousand kilometres from Madagascar in the West to Easter Island in the East. And, of course, like the Vikings (but much earlier), their civilization had only become possible by the exploitation of wind energy via the lift-type sail. In fact, descendents of the Austronesians (particularly the Polynesians) quite sensibly always attempted to make their discovery voyages in an upwind direction, thus allowing themselves a safe and rapid homeward journey with the wind [10].

Background:

[Sound of swords clashing and medieval soldiers shouting]

Voiceover:

It's strange to think that 700

years after the Norman conquest, the English-born descendents of the Vikings and the Normans would become so good at harnessing wind energy that they would voyage half-way round the world, and eventually come into contact with the descendents of the Austronesians -- a direct (but trivial) consequence of which is that this radio programme from New Zealand is broadcast in the English language.

But in 1066 it would have seemed absolutely inconceivable that the tiny country of England would go on to "rule the waves" of the world, and become the dominant power in the largest empire in human history. Surprisingly, however, a closer examination of this green and pleasant land reveals a number of plausible reasons why England (and later, Great Britain) had all the right ingredients to make such an outcome possible.

Background:

[Sound of wind over high-tension power lines]

Voiceover:

Obviously, an absolutely essential factor is that England had energy resources in the form of timber fuels, animal labour, flowing water, and wind. And they also had the technology to efficiently exploit these energy resources -- technology either inherited from the Romans, or borrowed from the (at that time) more advanced civilizations in Asia: in particular, China. Furthermore, England had numerous useful raw materials to transform with their energy resources, for example, metal ores such as iron and copper.

England also had the right environmental and political drivers. As Europe's only significant island nation they had the incentive to become experts at exploiting wind energy for seafare. They also existed in a state of competition and almost constant warfare with other European nations, which encouraged them to expand the borders of their empire. After all, if England didn't exploit an opportunity to conquer a weak foreign power, then they could be pretty sure that one of their

European enemies would certainly do so -- in order to augment their own economic and military might.

And, of crucial importance, England (and Western Europe in general) had the vast American continents almost on their doorstep -- or, at any rate, much closer than, for example, the Americas were to other major civilizations such as China.

Finally, the English (and, again, Western Europe in general) had luck. Their language was written with an alphabet that could be efficiently reproduced on a printing press, thus allowing for the rapid dissemination of new information and ideas [11]. And their close contact with agricultural animals for transport energy and food had given them an arsenal of unhealthy germs that would prove absolutely deadly to civilizations in the Americas, Australia, and Oceania [12].

Background:

[Sound of waves and seabirds]

Voiceover:

English mariners would reach North America in 1497 [13]. And shortly afterwards, King Henry VIII -- a descendent of William the Conqueror -- would form a professional English navy [14]. By the end of the 1600s, this navy had become the largest and most formidable in the world [15]; a state of affairs that would last (in the form of the Royal Navy) right up until the early years of the twentieth century [16].

Of course, English (and later British) naval ascendancy wasn't only a matter of efficiency in harnessing wind energy. The English also needed the energy resources and know-how to cost-effectively manufacture auxiliary items (such as metal fittings) for their battle fleets and merchant navy: in particular, to manufacture machines that would make devastating use of a Chinese invention that (when burnt) released energy at a tremendous rate -- gunpowder.

Background:

[Sound of wind over high-tension power lines]

Voiceover:

The material wealth and resources that resulted from their colonies on the American

continents provided the springboard for Britain to eventually seize huge tracts of Africa, Asia, Oceania, and the entire Australian continent [13]. At the apex of its glory, Britain ruled over a quarter of the world's population and land area [17], and had become so vast that -- famously -- the sun never set on its empire.

Background:

[Sound of fire burning]

Voiceover:

But, in order to achieve all this, England had to overcome an important obstacle: the energy bottleneck of its wood resources. The expansion of ship-building in the 1500s -- and the fuel needed for the accompanying manufacture of iron, steel, copper, lead, glass, and gunpowder -- resulted in a 'timber famine' throughout England [18]. These new industries consumed energy on a scale that had never been seen before: Sussex and Kent alone were home to around 7,000 smelters [18]. By the second half of the 1500s the timber famine had became so severe that parliament even passed legislation in an attempt to curb the use of timber as fuel [18].

In the same way that the harnessing of fire led to agriculture and eventually to energy from animal labour, the path to English supremacy in harnessing wind energy for transportation also led to the exploitation of an entirely new energy source. This is perhaps best described in the words of Edmund Howes, writing in 1631:

... there is so great scarcity of wood throughout the whole kingdom that not only the City of London, all haven towns and in very many parts within the land, the inhabitants in general are constrained to make their fires of sea-coal or pit coal, even in the chambers of honourable personages -- and through necessity which is the mother of all arts, they have in late years devised the making of iron,

the making of all sorts of glass, and the burning of bricks with sea-coal and pit-coal [rather than wood] [19].

Background:

[Sound of pick and shovel]

Voiceover:

The English timber famine and the consequent uptake of coal was the first step in the exploitation of a new energy source that would utterly transform the entire world. But more on that next week, when we go down -- into the pits.

Further information on this episode:

• Read about the history of England in Wikipedia.
  
  
• Read about the Vikings in Wikipedia.
  
  
Read about the Austronesians in Wikipedia.

This is a transcript of an episode of Public Address Science which was originally broadcast on Radio Live, 29th September 2007, 5 pm - 6 pm.

You can listen to the original audio version of the programme by clicking on the 'Play the audio for this post' link at the top of this page or the 'Audio' button at the bottom of this page.

Background:

[Sound of military drums and crowd chanting: "Caesar, Caesar, Caesar..."]
[Sound of wind over high-tension power lines]

Voiceover:

150 AD was a good year for the Roman Empire. In fact, arguably, things would never be better. The empire encircled the Mediterranean and stretched into Northern Europe as far as Britain. It touched the western edges of the European and African continents in what are now the countries of Portugal and Morocco, and it reached eastward into Asia as far as Azerbaijan. In the south it stretched into Africa to embrace the Red Sea and modern-day Sudan [1].

The Roman emperor in 150 AD bore the snappy name of Caesar Titus Aelius Hadrianus Antoninus Augustus Pius -- a man who Roman historians later described as the fourth of the five good Roman emperors -- and who (only two years previously) had presided over the celebrations for Rome's 900th anniversary [2].

Background:

[Sound of crowd chanting: "Caesar, Caesar, Caesar..."]

Voiceover:

And, unquestionably, one of the greatest jewels of the Roman Empire in its heyday -- and, certainly, its intellectual centre [3] -- was the city of Alexandria in what is now the country of Egypt.

Background:

[Sound of fire burning]

Voiceover:

In last week's episode, I talked about humankind's exploitation of the energy in plant biomass (via the process of burning), and how this enabled stone-age humans to make two paradigm shifts in development: firstly, to rise to the top of the food chain and spread out across the globe; and, secondly, to develop agriculture and harness additional energy in the form of animal labour. In the subsequent three-and-a-half thousand or so years between the first widespread use of animal labour, and the birth of the Roman Empire, the repercussions of energy from fire and animals unleashed a cascade of new

technologies. And the best place in the ancient world to learn all about these new technologies was the city of Alexandria in the Roman Empire.

Background:

[Sound of wind over high-tension power lines]

Voiceover:

The Mouseion in Alexandria [variously spelt Museion or Musaeum; from which we get the modern word 'museum'] was the empire's most famous scholarly institute [4]. It included the famous Library of Alexandria [5] -- and although this had probably been partially destroyed by 150 AD [6], it was still a vast repository of knowledge. Scholars at the Mouseion both archived and conducted research into history, literature, philosophy, science, and all forms of engineering.

Background:

[Egyptian street sounds]

Voiceover:

And if we were to walk out onto the streets of Alexandria as it was in 150 AD, we would see a city which -- from a technological perspective -- would appear (initially, at any rate) to be little different from a modern city of, say, three hundred years ago.

Alexandria is a clearly a city from the Age of Metals. The energy from fire has enabled the production of copper, bronze, wrought iron, and steel [7] -- and these materials are widely used in day-to-day living.

There are public baths with hot water, and even central heating [8]. Energy from animal labour is exploited to haul carts and wagons around the city. And in the harbour, sea-going vessels propelled by wind energy bob up-and-down in the waves.

Background:

[Sound of wind over high-tension power lines]

Voiceover:

And all of this has arisen from humankind's ability to exploit non-food forms of energy. Of course, there are clearly other factors involved as well. For example, metals can't exist without the appropriate ores being available, and agriculture can't exist without animal or plant species suitable for domestication. But, beyond that,

the single physical limiting factor is energy, and the technology to exploit it.

The cities of the Roman Empire, and the agricultural lands that supported them, and the Roman military forces, and the scale of the empire's trade and commerce on land and sea, simply would not have been possible -- and couldn't even have come into being -- without the exploitation of energy from fire, animal labour, and wind.

Background:

[Sound of horse and cart]

Voiceover:

Having noted the apparently advanced level of Roman technology, it therefore comes as a surprise when we take a closer look at the way they used their energy resources. For example, although they have greatly increased the load-carrying efficiency of horses by use of the wheel and axle (and the famous Roman roads), the harness system on Roman horses looks rather odd -- hardly more sophisticated than a dog-collar.

In fact, the Roman harness was extremely unsophisticated, and also extremely inefficient. It turns out that a horse with a late-medieval harness could haul about 15 times that of a human -- but a horse with a primitive Roman harness could only haul about four times that of a human [9]. And since a horse eats about four times as much as a human [9] then -- interestingly -- horse-power with an inefficient Roman harness only becomes sensible for applications that require speed rather than pure hauling ability.

Background:

[Egyptian street sounds]

Voiceover:

And that means that in the Roman Empire, human labour would very often be employed in situations where -- a thousand or so years later -- horses would have been used. Farms in the Roman period required a virtual army of labourers, many of whom would be simply lifting and carrying. The energy to run the construction cranes on Roman building

sites was derived from humans turning windlasses. And even the grain mills and water pumps were often powered by people running around inside machines that resembled enormous human-sized hamster wheels [10].

Background:

[Sound of waves and seabirds]

Voiceover:

And what about those Roman sailing ships bobbing about in the harbour? They're certainly a triumph of craftsmanship -- but a closer look at the sails reveals another surprise. The design is dramatically different from that which would be used in Europe a millennia later. The Roman ships used drag-type sails, which can only provide tractive force in the same direction as the wind [11]. If the captain wishes to sail against the wind, his only option is to lower the sails, and order his team of rowers to get to work.

So, although Alexandria in 150 AD initially appears to be technologically similar to cities of only two or three hundred years ago -- in its use of fire, animal labour, and wind energy -- in turns out that the major source of energy for useful work in the Roman Empire was, in fact, animal labour from other humans. In other words: slavery.

Background:

[Sound of military drums]

Voiceover:

First and foremost, Rome was always a military power. The Roman Republic existed in a state of continuous warfare and conquest [12]. Military victories resulted in the transfer of enormous material resources into Rome [13] -- and none was more important than slaves. Slaves (and other spoils of war) enabled the Romans both to consolidate their conquests, and also to embark on further expansion [12].

Vast numbers of slaves were used on the Roman agricultural estates. Slaves performed essential work in the factories of the Roman cities. Hordes of slaves rowers allowed Roman ships to travel against the wind. And slaves provided

the labour in the Roman metal-mining industry.

Background:

[Sound of wind over high-tension power lines]

Voiceover:

Historians estimate that in the first century of the empire, Rome consumed between one hundred thousand and half-a-million slaves every single year [14][15]. The slaves used for hard agricultural labour and as rowers in Roman ships had a life-expectancy of perhaps only a few years -- and those in the mines only a few months. Slaves were, quite simply, an energy resource to be exploited. Nevertheless, despite the high mortality rate, such was the quantity of slave imports that they comprised between 30 and 40 per cent of the population in the empire's Italian provinces -- an enormous proportion [14].

Background:

[Egyptian street sounds]

Voiceover:

Now the year 150 AD is particularly interesting in terms of slavery. Nine hundred years of continuous Roman growth and expansion has reached its peak under the Emperor Trajan in 116 AD [16]. In the subsequent decades, the supply of new slaves began to slow. Breeding programmes, piracy, poverty slavery, and child abandonment within the empire proved insufficient to make up the shortfall of new slaves -- and, around 150 AD, the demand for slaves began to exceed supply, and labour shortages began to seriously affect the empire [15].

Which provides an interesting lesson: what happens to a civilization when its main energy source begins to run out? At the very least, economic and political instability. But this need not be a mortal blow: for example, in the case of Rome, technological development in terms of a more efficient horse-harness or lift-type sails on Roman ships could, perhaps, have greatly reduced the empire's energy consumption for agriculture and transport.

And, of course, wind-power, waterwheels [17], and possibly even tide-wheels [18] were all known technologies that would have been documented

in the Library of Alexandria. But these required the right sort of rivers, the right sort of tidal location, or a reliable supply of wind. And besides, from the Roman perspective, slavery was clearly a winning formula -- after all, Rome had prospered for 900 years on the energy of its slaves.

Background:

[Sound of wind over high-tension power lines]

Voiceover:

Clearly, there were many contributory factors in the collapse of the Roman Empire. But I would argue that energy was a critical underlying cause -- often overlooked -- that ties together a number of other important factors. To put it in very simple terms, the importation of energy in the form of slaves allowed Rome to expand beyond an internally sustainable size. When the energy imports stopped -- then civilization collapsed back to its sustainable limits. The western empire fragmented into smaller regions, and the less energy-dependent east (which was more densely populated; had easier trade routes into Arabia, China, and India [19]; and was historically less dependent on slavery [15]) became the Byzantine empire.

Background:

[Sound of waves and seabirds]

Voiceover:

One of the themes of this series is that the exploitation of energy has allowed civilization to arise -- but the Roman empire may well provide a cautionary example that the reverse can also happen when energy resources are lost.

Next week, on a more cheerful note, we step forward in history to an obscure former part of the Roman Empire -- and onto the high seas...

Further information on this episode:

• Read about the Roman Republic in Wikipedia.
  
  
• Read about the Roman Empire in Wikipedia.
  
  
Read about the The Mouseion in Wikipedia.


• Read about the The Library of Alexandria in Wikipedia.
  
  
Read about Slavery in Wikipedia.

This is a transcript of an episode of Public Address Science which was originally broadcast on Radio Live, 8th September 2007, 5 pm - 6 pm.

You can listen to the original audio version of the programme by clicking on the 'Play the audio for this post' link at the top of this page or the 'Audio' button at the bottom of this page.

Background:

[Short sound sample from 2001: A Space Odyssey]

Voiceover:

In the somewhat overwrought opening sequence of the film 2001: A Space Odyssey, our primitive ancestors are depicted as making a leap in development when they receive enlightenment from what appears to be an enormous singing block of Lego.

In fact, the reality of our ancestors' first paradigm shift in cultural development -- with the discovery of fire -- was almost equally as dramatic. Last week, I talked about humankind's ability to harness non-food forms of energy; the scale of which distinguishes us from all other animal species. And fire is where it all started. For the first time, a species was making use of the solar energy stored by plants not via the process of eating them, but by burning them: thus releasing the stored energy at a much higher rate than would otherwise be possible.

Now the conventional view of history is that as civilization has slowly developed, so new forms of energy have been harnessed. But over the next few episodes, I'm going to argue that that point-of-view is exactly the wrong way around. What I'm going to propose is that the harnessing of new forms of energy (or the exploitation of old forms in dramatically more efficient ways) has allowed humankind to make paradigm leaps in development -- and it is only after these leaps in development have taken place, that new forms of civilization have been able to grow and flourish.

Background:

[Sound of fire burning]

Voiceover:

And the very first of these paradigm leaps occurred when ancient hominids exploited the energy in plant material by burning it. The date of fire's first use is somewhat disputed by anthropologists, but a reasonable mid-point figure of the various theories would be around five hundred thousand years

ago (although there's evidence that it could be as early as one-and-a-half million years ago)[1][2][3].

What isn't disputed, however, is fire's enormous impact. The thermal energy (or heat) released by the combustion of plant biomass not only enabled early hominids to ward off predators -- but also enabled them to hunt game much more effectively, by using fire to flush animals out of forest areas, and into places where they could easily be slaughtered [4].

Furthermore, the judicious burning of vegetation enabled large-scale modification of the local environment. The removal of scrub and forest by fire made it possible to produce the conditions which favoured edible plants for gathering, or to create the types of habitat (and stimulate the secondary growth of vegetation) that would attract game animals for hunting [4].

And not only that, but small controlled 'camp' fires provided light during the night, and -- more importantly -- produced sufficient supplementary heat to enable hominids to spread out from their original habitat in the tropical regions, and migrate vast distances into Northern Europe and Central Asia [5].

Background:

[Sound of potatoes boiling on gas cooker in kitchen]

Voiceover:

And lastly, of course, fire enabled the cooking of foods.

Cooking is something we do so often that we almost forget the many benefits that it provides. For a start, it allows the human digestive system to extract a greater quantity of energy from meat and many edible plants [6]. It also kills food-borne diseases and parasites [7](a fact that's quite reassuring if you're ever invited to dinner at a student flat).

And, of course, cooking makes palatable otherwise inedible plants [7] such as acorns, cassava, karaka berries, and -- one of the foods I'm preparing tonight -- potatoes. Fire even allows the preservation of food through drying and smoking

[8].

Background:

[Sound of wind over high-tension power lines]

Voiceover:

But it's one of the implications of food cooking that's perhaps the most interesting point about the early use of fire. You may not have noticed, but I've been very careful to use the word hominid rather than human. That's because the first beings to harness energy by burning plant material weren't human -- they were of the species Homo erectus [9]. And they were using fire in a controlled manner for at least three hundred thousand years (or possibly much longer) before the arrival of Homo sapiens (modern humans).

Background:

[Sound of chewing]

Voiceover:

Now some anthropologists have speculated that the ability to cook food with fire was especially important. They theorize that cooking acted to de-emphasize the evolutionary importance of chewing, and therefore made the skull strength required to support the massive jaw muscles found on Homo erectus much less necessary. And, in turn, this made it possible for subsequent hominid species (such as humans) to function with larger less-sturdy skulls, which could house correspondingly bigger brains [7].

If this theory is correct, then it could be said that fire didn't just enable early human civilization to develop -- but that the harnessing of fire by earlier hominid species actually made it possible for human beings to come into existence in the first place. And if that isn't a dramatic consequence of energy usage then I don't know what is.

Background:

[Sound of fire burning]

Voiceover:

Now it's a fascinating (and slightly bewildering) fact, that although fire has been used by hominids for perhaps half a million years -- for most of that time, nobody actually knew how to make it. Again, the exact date is uncertain, but a ballpark mid-point of the estimates for when humans first

figured out how to use fire-bows, fire-saws, or flint to produce a flame, is around 10,000 BC [10][11] -- ironically, just in time for the end of the last ice age.

Before then, fire was gathered from naturally occurring events -- predominantly as a result of lightning strikes. Once gathered, the fire had to be kept constantly burning in sheltered locations such as caves, although it could be transported over quite long distances by carrying embers (damped with soil, moss, or leaves) [8] in receptacles such as hollow logs. However this was a risky business, because for early hominids the consequences of fire going out could very easily prove fatal [8].

The ability to make fire (rather than just gather it) was one of the first steps in what some have termed the Neolithic (or new stone age) revolution. The very next step was another dramatic change: the development of agriculture.

Background:

[Sound of a New Zealand farm]

Voiceover:

It's been suggested that hunter-gatherers' manipulation of the landscape through fire to favour their preferred types of plant and game, led naturally onto the concept of domesticating animals and crops. That's something that will probably never be proved one way or the other, but what can be asserted without contradiction is that (with the possible exception of certain riverine habitats) Homo sapiens could only embrace agriculture by the use of fire [12].

Fire created the type of pasture that I'm standing in now -- which is required for grazing animals. It purged the fields of weed seeds and pathogens prior to the planting of crops. It promoted nitrogen-fixing bacteria, and the ash from fire released valuable nutrients into the soil. Until the advent of fossil fuels the energy required to perform these tasks was simply not available from any source other

than the burning of plant biomass.

In fact, the Neolithic style of agriculture with fire -- termed fire-fallow farming [13] and fire-forage herding [14] -- is still being used today. Controlled burn-offs are an annual event on many modern farms in New Zealand and elsewhere in the world [15].

Background:

[Sound of horse hooves on cobbles]

Voiceover:

Agriculture brought a population explosion, and the development of permanent human settlements such as villages, towns, and eventually cities. And, of course, it also led directly to humankind's second great source of energy: animal labour. By 3000 BC pack animals were being widely used in North Africa, Europe, and throughout Asia [16] -- a development which greatly increased both the quantity and range of trade goods. And, shortly after this date, archaeological evidence shows that animal power was being used to pull ploughs and haul wheeled vehicles in what is now modern-day Iraq [16].

Background:

[Sound of a blacksmith working]

Voiceover:

But energy from animals was only possible with agriculture, which, in turn, required energy from fire. The next technology that would arise from the flames (so to speak), would propel humanity right out of the stone age -- and into the age of metals.

But more on that next week, when we visit one of the great cities of the ancient world: Alexandria.

Further information on this episode:

• Read about the Palaeolithic period in Wikipedia.
  
  
• Read about the Neolithic period in Wikipedia.
  
  
Read more about fire in: Pyne, Stephen. J. (2001) Fire : a brief history. British Museum, London.