Science of Discworld III

by Terry Pratchett

  And so the steam engine bumbled along, never disappearing entirely, but never making any kind of breakthrough. In 1120 the church at Rheims had what looks suspiciously like a steam-powered organ. In 1571 Matthesius described a steam engine in a sermon. In 1519 the French academic Jacob Besson wrote about the production of steam and its mechanical uses. In 1543 the Spaniard Balso de Garay is reputed to have suggested the use of steam to power a ship. Leonardo da Vinci described a steam-gun that could throw a heavy metal ball. In 1606 Florence Rivault, gentleman of the bedchamber to Henry IV, discovered that a metal bombshell would explode if it was filled with water and heated. In 1615, Salomon de Caius, an engineer under Louis XIII, wrote about a machine that used steam to raise water. In 1629 … but you get the idea. It went on like that, with person after person reinventing the steam engine, until 1663.

  In that year Edward Somerset, Marquis of Worcester, not only invented a steam-powered machine for raising water: he got it built, and installed, two years later, at Vauxhall – now part of London, but then just outside it. This was probably the first genuine application of steam power to a serious practical problem. No drawing of the machine exists, but its general form has been inferred from grooves, still surviving, in the walls of Raglan Castle, where it was installed. Worcester planned to form a company to exploit his machine, but failed to raise the cash. His widow in her turn made the same attempt, with the same lack of success. So that’s another necessary ingredient for steam engine time: money.

  In some ways, Worcester was the true creator of the steam engine, but he gets little credit, because he was just a tiny bit ahead of the wave. He does mark a moment at which the whole game changed, however: from this point on, people didn’t just invent steam engines – they used them. By 1683, Sir Samuel Morland was building steam-powered pumps for Louis XIV, and his book of that year reveals a deep familiarity with the properties of steam and the associated mechanisms. The idea of the steam engine had now arrived, along with a few of the things themselves, earning their living by performing useful tasks. But it still wasn’t steam engine time.

  Now, however, the momentum began to grow rapidly, and what gave it a really big push was mining. Mines, for coal or minerals, had been around for millennia, but by the start of the eighteenth century they were becoming so big, and so deep, that they ran into what quickly became the miner’s greatest enemy: water.

  The deeper you try to dig mines, the more likely they are to become flooded, because they are more likely to run into underlying reservoirs of water, or cracks that lead to such reservoirs, or just cracks down which water from above can flow. Traditional methods of removing water were no longer successful, and something radically different was needed. The steam engine filled the gap neatly. Two people, above all, made it possible to build suitable machinery: Dennis Papin and Thomas Savery.

  Papin trained in mathematics under the Jesuits at Blois, and in medicine in Paris, where he settled in 1672. He joined the laboratory of Robert Boyle, who would nowadays be called an experimental physicist. Boyle was working on pneumatics, the behaviour of gases – ‘Boyle’s law’, relating the pressure and volume of a gas at constant temperature, continues to be taught to this day. Papin invented the double air pump and the air gun, and then he invented the Digester. This is best described as a pressure-cooker, which is a saucepan with thick walls and a thick lid, held on securely so that water inside boils to form high-pressure steam. Food contained in the pan cooks very quickly.

  The cookery aspect doesn’t affect our story, but one bit of technology does. To avoid explosions, Papin added a safety valve, a feature replicated in the sixties domestic version, and an important invention because early involvement with steam engines was dangerous at the best of times. The idea probably originated earlier, but Papin gets the credit for using it to control steam pressure. In 1687 he moved to the University of Marburg, where he invented the first mechanical steam engine and the first piston engine. Throughout his career, he carried out innumerable experiments with steam-related apparatus, and introduced many significant pieces of gadgetry.

  Steam engine time was hotting up. Savery, who also trained in mathematics, brought it to the boil. In 1698 he patented the first steam-powered pump that was actually used to clear mines of unwanted water – in this case, the deep mines of Cornwall. He sent a working model to the Royal Society, and later showed a model ‘fire engine’, as the machines were then confusingly called, to William III. The King granted him a patent:

  A grant to Thomas Savery of the sole exercise of a new invention by him invented, for raising of water, and occasioning motion to all sorts of mill works, by the important force of fire, which will be of great use in draining mines, serving towns with water, and for the working of all sorts of mills, when they have not the benefit of water nor constant winds; to hold for 14 years; with usual clauses.

  Steam engine time was close at hand. What clinched it was that Savery was a born businessman. He didn’t wait for the world to beat a path to his door: he advertised. He gave lectures at the Royal Society, some of which were published in its journals. He circulated a prospectus among mine-owners and managers. And the selling point, naturally, was profit. If you can open up deeper levels of your mine, you can extract more minerals and make more money out of the same mine and the same bit of land.

  Two more major steps were needed before what Thurston calls the ‘modern’ steam engine – that of 125 years ago – became firmly established. The first was to move from specialised, single-purpose machines, to multi-purpose ones. The second was to improve the engine’s efficiency.

  The move to multi-purpose steam engines was made by Thomas Newcomen, a blacksmith by trade, who introduced a radical new kind of engine, the ‘atmospheric steam engine’. Previous engines had effectively combined a steam-driven piston and a pump in the same apparatus. Newcomen separated the components, and threw in a separate boiler and a condenser to boot. The piston moves up and down like a ‘nodding donkey’, driving a rod, which can be attached to … anything you like. Another engineer who must be mentioned here was John Smeaton, who scaled Newcomen’s design up to much larger size.

  Now, finally, we come to James Watt. Whatever credit he deserves, it is clear that he stood on the shoulders of a number of giants. Even if he had been capable of inventing the steam engine on his own, the plain fact is that he didn’t. His grandfather was a mathematician – there seem to be a lot of mathematicians in the history of the steam engine – and Watt inherited his abilities. He carried out lots of experiments, and he made quantitative measurements, a relatively new idea. He worked out how heat travelled through the materials of the engine, and how much coal it took to boil a given amount of water. And he realised that the key to an efficient steam engine was to control unnecessary heat loss. The worst loss occurred in the cylinder that powered the piston, which kept changing temperature. Watt realised that the cylinder should always be kept at the same temperature as the steam that entered it – but how could that be done? The answer, when he finally chanced upon it, was simple and elegant:

  I had gone to take a walk on a fine Sabbath afternoon. I had entered the Green by the gate at the foot of Charlotte Street, and had passed the old washing-house. I was thinking upon the engine at the time, and had gone as far as the herd’s house, when the idea came into my mind that, as steam was an elastic body, it would rush into a vacuum, and, if a communication were made between the cylinder and an exhausted vessel, it would rush into it, and might be condensed there without cooling the cylinder … I had not walked farther than the Golf-house, when the whole thing was arranged in my mind.

  Such an easy thing to come up with – don’t cool the steam in the cylinder, cool it somewhere else. Yet it improved the machine’s efficiency so much that within a few years the only steam engines that anyone even thought of installing were those of Watt and his financial partner Boulton. Boulton-and-Watt engines cornered the market. No really significant improvements were subsequently made
to their design. Or, to be more accurate, later ‘improvements’ supplanted the steam engine with engines of a very different design, driven by coal and oil. The steam engine had evolved to the pinnacle of its existence, and what displaced it was, in effect, a new species of engine altogether.

  In retrospect, steam engine time arrived around the period of Savery, when the ability to make practical machines coincided with a genuine need for them in an industry that could afford to pay for them and would make more profits as a result. Add to that a sound business mind, to notice the situation and exploit it, and a sense for publicity to raise money from investors and get the idea off the ground, and the steam engine went like a … train.

  Ironically, before most people realised that steam engine time had arrived, it had gone, again, and in the end there was only one winner. The rest of the competition fell by the wayside. And that is why Watt gets so much credit, and why, ultimately, he deserves it. But he also deserves credit for his systematic quantitative experiments, his focus on the theory behind the steam engine, and his development of the concept – not as its inventor.

  Certainly not for watching a kettle as a kid.

  The history of the introduction of the Boulton-and-Watt steam engine is essentially an evolutionary one: the fittest design survived, the less fit were superseded and vanished from the historical record. Which brings us to Darwin, and natural selection. The Victorian era was ‘steam engine time’ for evolution; Darwin was just one of many people who recognised the mutability of species. Does he deserve the credit he gets? Was he, like Watt, the person who brought the theory to its culmination? Or did he play a more innovative role?

  In the introduction to Origin, Darwin mentions several of his predecessors. So he certainly wasn’t trying to take credit for the ideas of others. Unless you subscribe to the rather Machiavellian school of thought that giving credit to others is just a sneaky way of damning them with faint praise. One predecessor that he does not mention is perhaps the most interesting of all – his own grandfather, Erasmus Darwin. Perhaps Charles felt that Erasmus was a bit too nutty to mention, especially being a relative.

  Erasmus knew James Watt, and may have helped him to promote his steam engine. They were both members of the Lunar Society, an organisation of Birmingham technocrats. Another was Josiah Wedgwood, Darwin’s uncle Jos’s grandfather and founder of the famous ceramics company. The ‘Lunaticks’ met once a month at the time of the full moon – not for pagan or mystic reasons, or because they were all werewolves, but because that way they could see their way easily as they rode home after a few drinks and a good meal.

  Erasmus, a physician, could also turn a nifty hand to machinery, and he invented a new steering mechanism for carriages, a horizontal windmill to grind Josiah’s pigments, and a machine that could speak the Lord’s Prayer and the Ten Commandments. When the 1791 riots against ‘philosophers’ (scientists) and for ‘Church and King’ put paid to the Lunar Society, Erasmus was just putting the finishing touches to a book. Its tide was Zoonomia, and it was about evolution.

  Not, however, by Charles’s mechanism of natural selection. Erasmus didn’t really describe a mechanism. He just said that organisms could change. All plant and animal life, Erasmus thought, derived from living ‘filaments’. They had to be able to change, otherwise they’d still be filaments. Aware of Lyell’s Deep Time, Erasmus argued that:

  In the great length of time, since the earth began to exist, perhaps millions of ages before the commencement of the history of mankind, would it be too bold to imagine, that all warm-blooded animals have arisen from one living filament, which the first great cause endowed with animality, with the power of acquiring new parts, attended by new propensities, directed by irritations, sensations, volitions, and associations; and thus possessing the faculty of continuing to improve by its own inherent activity, and of delivering down those improvements by generation to its posterity, world without end!

  If this sounds Lamarckian, that’s because it was. Jean-Baptiste Lamarck believed that creatures could inherit characteristics acquired by their ancestors – that if, say, a blacksmith acquired huge muscular arms by virtue of working for years at his forge, then his children would inherit similar arms, without having to do all that hard work. Insofar as Erasmus envisaged a mechanism for heredity, it was much like Lamarck’s. That did not prevent him having some important insights, not all of them original. In particular, he saw humans as superior descendants of animals, not as a separate form of creation. His grandson felt the same, which is why he called his later book on human evolution The Descent of Man. All very proper and scientific. But Ridcully is right. ‘Ascent’ would have been better public relations.

  Charles certainly read Zoonomia, during the holidays after his first year at Edinburgh University. He even wrote the word on the opening page of his ‘B Notebook’, the origin of Origin. So his grandfather’s views must have influenced him, but probably only by affirming the possibility of species change.3 The big difference was that from the very beginning, Charles was looking for a mechanism. He didn’t want to point out that species could change – he wanted to know how they changed. And it is this that distinguishes him from nearly all of the competition.

  The most serious competitor we have mentioned already: Wallace. Darwin acknowledges their joint discovery in the second paragraph of the introduction to Origin. But Darwin wrote an influential and controversial book, whereas Wallace wrote one short paper in a technical journal. Darwin took the theory much further, assembled much more evidence, and paid more attention to possible objections.

  He prefaced Origin with ‘An Historical Sketch’ of views of the origin of species, and in particular their mutability. A footnote mentions a remarkable statement in Aristode, who asked why the various parts of the body fit together, so that, for example, the upper and lower teeth meet tidily, instead of grinding against each other. The ancient Greek philosopher anticipated natural selection:

  Wheresoever, therefore, all things together (that is all the parts of one whole) happened like as if they were made for the sake of something, these were preserved, having been appropriately constituted by an internal spontaneity; and whatsoever things were not thus constituted, perished, and still perish.

  In other words: if by chance, or some unspecified process the components carried out some useful function, they would appear in later generations, but if they didn’t, the creature that possessed them would not survive.

  Aristotle would have made short shrift of Paley.

  Next, Darwin tackles Lamarck, whose views date from 1801. Lamarck contended that species could descend from other species, mostly because close study shows endless tiny graduations and varieties within a species, so the boundaries between distinct species is much fuzzier than we usually think. But Darwin notes two flaws. One is the belief that acquired characteristics can be inherited – Darwin cites the giraffe’s long neck as an example. The other is that Lamarck believed in ‘progress’ – a one-way ascent to higher and higher forms of organisation.

  A long series of minor figures follows. Among them is one noteworthy but obscure fellow, Patrick Matthew. In 1831, he published a book about naval timber, in which the principle of natural selection was stated in an appendix. Naturalists failed to read the book, until Matthew drew attention to his anticipation of Darwin’s central idea in the Gardener’s Chronicle in 1860.

  Now Darwin introduces a better-known forerunner, the Vestiges of the Natural History of Creation. This book was published anonymously in 1844 by Robert Chambers; it is clear that he was also its author. The medical schools of Edinburgh were awash with the realisation that entirely different animals have remarkably similar anatomies, suggesting a common origin and therefore the mutability of species. For example, the same basic arrangement of bones occurs in the human hand, the paw of a dog, the wing of a bird, and the fin of a whale. If each were a separate creation, God must have been running out of ideas.

  Chambers was a socialite – he pla
yed golf – and he decided to make the scientific vision of life on Earth available to the common man. A born journalist, Chambers outlined not just the history of life, but that of the entire cosmos. And he filled the book with sly digs at ‘those dogs of the clergy’. The book was an overnight sensation, and each successive edition slowly removed various blunders that had made the first edition easy to attack on scientific grounds. The vilified clergy thanked their God that the author had not begun with one of the later editions.

  Darwin, who respected the Church, had to refer to Vestiges, but he also had to distance himself from it. In any case, he found it woefully incomplete. In his ‘Historical Sketch’, Darwin quoted from the tenth ‘and much improved’ edition, objecting that the anonymous author of Vestiges cannot account for the way organisms are adapted to their environments or lifestyles. He takes up the same point in his introduction, suggesting that the anonymous author would presumably say that:

  After a certain number of unknown generations, some bird had given birth to a woodpecker, and some plant to the misseltoe [sic], and that these had been produced perfect as we now see them; but this assumption seems to me to be no explanation, for it leaves the case of the coadaptations of organic beings to each other and to their physical conditions of life, untouched and unexplained.

  More heavyweights follow, interspersed with lesser figures. The first heavyweight is Richard Owen, who was convinced that species could change, adding that to a zoologist the word ‘creation’ means ‘a process he knows not what’. The next is Wallace. Darwin reviews his interactions with both, at some length. He also mentions Herbert Spencer, who considered the breeding of domesticated varieties of animals as evidence that species could change in the wild, without human intervention. Spencer later became a major populariser of Darwin’s theories. He introduced the memorable phrase ‘survival of the fittest’, which unfortunately has caused more harm than good to the Darwinian cause, by promoting a rather simple-minded version of the theory.