Science of Discworld III

isn’t always clear-cut. Did ancient humans discover fire as a phenomenon of nature, or did they invent fire as a technology to keep predators away, light the cave, and cook food? The natural phenomenon surely came first, in the form of brush- or forest fires triggered by lightning, or possibly a droplet of water accidentally acting as a lens to concentrate the Sun’s rays on to a piece of dry grass. 1
    However, that kind of ‘discovery’ doesn’t go anywhere until someone finds a use for it. It was the idea of controlling fire that made the difference, and that seems more of an invention than a discovery. Except … you find out how to control fire by discovering that fires don’t spread (so easily) across bare soil, that they can be spread very easily indeed by picking up a burning stick and dropping it into dry brushwood, or taking it home to the cave …
    The inventive step, if there is such a thing, consists of putting together several independent discoveries so that what emerges has genuine novelty.
    So inventions are often preceded by a series of discoveries. Similarly, discoveries are often preceded by inventions. The discovery of sunspots rested on the invention of the telescope, the discovery of amoebas and Parameciums in pond water rested on the invention of the microscope. In short, invention and discovery are intimately entwined, and it’s probably pointless to try to separate them. Moreover, the significant instances of both are much easier to spot in retrospect than they were at the time they first happened. Hindsight is a wondrous thing, but it does have the virtue of providing an explicit context for working out what did, or did not, matter. Hindsight lets us organise the remarkably messy process of invention/discovery, and tell convincing stories about it.
    The problem is, most of those stories aren’t true.
    As children, many of us learned how the steam engine was invented. The young James Watt, aged about six, was watching a kettle boil, and he noticed that the pressure of the steam could lift the lid. In a classic ‘eureka’ moment, it dawned on him that a really big kettle could lift really heavy bits of metal, and the steam engine was born.
    The original teller of this story was the French mathematician François Arago, author of one of the first biographies of Watt. For all we know, the story may be true, though it is more likely a ‘lie-to-children’, or educational aid, 2 like Newton’s apple. Even if the young Watt was indeed suddenly inspired by a boiling kettle, he was by no means the first person to make the connection between steam and motive power. He wasn’t even the first person to build a working steam engine. His claim to fame rests on something more complex, yet more significant. In Watt’s hands, the steam engine became an effective and reliable tool. He didn’t ‘perfect’ it – many smaller improvements were made after Watt – but he brought it into pretty much its final form.
    Watt wrote in 1774: ‘The fire engine [= steam engine] that I have invented is now going, and answers much better than any other that has yet been made.’ In conjunction with his business partner Matthew Boulton, Watt made himself the household name of the steam engine. And it has done his reputation no harm that, in the words of Thurston: ‘Of the personal history of the earlier inventors and improvers of the steam-engine, very little is ascertained; but that of Watt has become well known.’
    Was Darwin just another Watt? Did he get credit for evolution because he brought it into a polished, effective form? Is he famous because we happen to know so much about his personal history? Darwin was an obsessive record-keeper, he hardly threw away a single scrap of paper. Biographers were able to document his life in exceptional detail. It certainly did his reputation no harm that such a wealth of historical material was available.
    In order to make comparisons, let’s review the history of the steam engine, avoiding lies-to-children as much as we can. Then we’ll look at Darwin’s intellectual predecessors, and see whether a common pattern emerges. How does steam engine time work? What factors lead to a cultural explosion, as an apparently radical idea ‘takes off’ and the world changes for ever? Does the idea change the world, or does a changing world generate the idea?
    Watt completed his first significant steam engine in 1768, and patented it in 1769. It was preceded by various