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.