by Bill Bryson
CHARGED ATMOSPHERES, OR HOW TO MAKE A LIGHTNING ROD
The principle of such lengthy and lofty pointed metal rods as a defence against lightning rested on a mix of old and recent thinking. Since the early eighteenth century, experimenters had been able to make electric sparks and shocks using friction machines of glass, leather and metal. These were lucrative items in their shows. ‘Lightning is in the hands of nature what electricity is in ours’, the London instrument maker George Adams put it, ‘the wonders we now exhibit at pleasure are little imitations of the great effects which frighten and alarm us’.15 The imitation analogised the stormy atmosphere with glass jars and metal rods inside their well-stocked rooms. According to the Royal Society’s leading electrical experimenter, the apothecary William Watson, ‘we see every day more and more the perfect analogy (to compare great things with small) between the highly electrified glass jar in the experiment and a cloud replete with the matter of thunder’.16
In early 1748 Watson read the Society a letter from an ingenious printer in Philadelphia, second city of the British empire. Quaker networks linking London with the City of Brotherly Love helped news of Benjamin Franklin’s experiments reach the Society. His demonstrations were supposed to show that electrical fire was an unevenly distributed active fluid gathered in atmospheres round bodies: the fluid would flow so as to restore balance, a satisfying thought for a prudent book-keeper, between excess (or positively charged) and deficient (or negatively charged) regions. Sparks and lightning were such restorative flows, if in dramatic form. As often, the Society initially held that what was right in Franklin’s story was already well known and what was wrong must be rejected. Even so, these stories about charged atmospheres were judged prize-winning achievements in electrical philosophy. In 1753 the Society’s new President, the Earl of Macclesfield, otherwise preoccupied with persuading a slightly unwilling nation to accept a foreign Gregorian calendar and thus seemingly lose eleven days of its precious time, awarded the Society’s prestigious Copley Medal to Franklin. ‘True it is’, observed the noble Earl, ‘that several learned Men, both at home and abroad, do not entirely agree with him in all the Conclusions he draws, and the Opinions which he thinks may be deduced from the Experiments he has made.’ However, he remarked, though not yet entirely convincing nor even a Fellow, at least Franklin was ‘a Subject of the Crown of Great Britain’.17 All that changed in the next two decades: following Franklin’s move to Europe, his theory would become Society orthodoxy, he won a Fellowship and helped liberate his nation from British rule.
The colonial medallist’s new invention was the lightning rod, first announced in his Philadelphia almanac the same year as his Royal Society prize. Since he found in his experiments that sharp needles could quietly withdraw electrical fire from the atmosphere of charged objects some inches away, so on a grander scale pointed metal rods well connected to damp earth should let electrical fire flow silently between the Earth and thunder clouds. He offered hope of disarming lightning, just as the mythical Prometheus had stolen fire from Olympus for humanity’s benefit and was thus punished by Zeus. Many Enlightenment sages, including Immanuel Kant, compared Franklin with the fabled Titan. One popular 1770s English writer on farming and weather put it pithily: ‘Dr Benj. Franklin’s soaring genius has realised the fable of Prometheus’ bringing fire down from heaven’.18 The Secretary of the French Royal Academy of Sciences apologised to Franklin in 1773 that ‘I have never had the happiness to meet the modern Prometheus’.19 The poet, philosopher and botanist Erasmus Darwin admired Franklin’s heroism, but guessed Prometheus’ punishment after stealing heavenly fire was really an allegory for a gin-soaked hangover. There were some more seriously dissident voices. An eminent French experimenter, sceptical of the worth of these fashionable rods, warned of the lethal dangers ‘were we to bring into being the Prometheus of the fable’.20 Within a generation the American with his lightning rods would be celebrated as victor over both tyranny and thunderbolts in a single evocative image of ingenuity and independence.
It seemed to many storytellers that since the rods were obviously rational and effective, any opposition to their use must stem from popular and religious narrow-mindedness. An English traveller in southern Germany was ‘told that the people of Bavaria were at least 300 years behind the rest of Europe in philosophy and useful knowledge’, so they still riskily rang church bells during thunderstorms to ward off threats.21 When fierce storms hit not only Norfolk but also lands across the North Sea in 1781, many Dutch and Flemish bell ringers died. From summer 1781 the city of Arras in northern France was racked by a lawsuit because of citizens’ opposition to a new lightning rod: the rod’s safety was successfully defended by a precise young lawyer with the schoolboy nickname ‘The Barometer’. His real name was Maximilien Robespierre, a man soon to be identified with Terror.22 One East Anglian minister reflected on an old story about members of a congregation marked with the sign of the cross after lightning hit their cathedral and wished ‘the Bishop’s attention had not been so much absorbed in the wonderful’.23 When a reckless Russian experimenter tried the electricity of his woefully arranged rod in a thunderstorm, he was killed. In response to this electric martyrdom, London’s Gentleman’s Magazine commented that ‘we are come at last to touch the celestial fire, which if we make too free with, as it is fabled Prometheus did of old, like him we may be brought too late to repent of our temerity’.24
However fabulous such tales, resistance to these devices was not entirely based on prejudiced ignorance. It is just as wrong to assume that scriptural fundamentalism completely explains why many nineteenth-century commentators challenged Darwin’s model of natural selection. Promethean science is debatable and its standing is never explicable by rough-shod appeals to lack of knowledge and to bigotry. There were reasons to wonder about, as well as wonder at, the modern Prometheus. Franklin’s account was the best the Society’s Fellows knew, but ambiguous and in several ways false. His small-scale experiments suggested to him that rods must be sharply pointed and could silently draw electrical charge from the dangerous atmospheres of thunder clouds. Modern sciences say both claims are untrue. On the vast scale of a lightning strike, the difference between pointed and blunt rods doesn’t matter. There’s evidence that pointed tips can make lightning rods into bad receptors. These rods cannot quietly discharge a cloud and their presence in an electrically charged region can make a strike more likely. But Franklin never abandoned his claims that rods could prevent a strike and had to be sharply pointed, just like those Mr Bobbitt erected at Heckingham in 1777 and which failed to work in 1781. ‘A long pointed rod’, Franklin told the Royal Society in 1772, ‘may prevent some strokes as well as conduct others that fall upon it.’ 25 Throughout the period these compelling but dubious claims were among the Royal Society’s major preoccupations.
When news broke that the Heckingham House of Industry had been equipped with high pointed rods but nevertheless caught fire, one of Franklin’s closest allies told him the Ordnance Board and the King were involved because ‘these events have a tendency to discredit conductors’.26 In ways familiar from more recent episodes of public science, such as the fracas surrounding food safety and BSE, the MMR vaccine, or the environmental effects of genetically modified crops, matters of concern seem to demand sure-fire judgments from trusted experts. So authorities called on the Royal Society for unequivocal decision. It is familiar, too, with sensational reports and rival experts in question, that public debate seems very wayward.
In these respects the Heckingham catastrophe was neither unprecedented nor straightforward. For two decades before 1781 the Society faced many episodes when across southern England houses, churches, powder magazines and other buildings guarded by rods had been struck or damaged by lightning. The Board of Ordnance, the clergy of St Paul’s Cathedral and the monarch all demanded certainty. The Fellows developed a kind of electrical fieldwork, involving visits to the stricken buildings, interviews with workmen, excavation of the
rods’ connections and collection of melted metal despatched to the Society. They trusted gentry ‘well known to many in the Royal Society’.27 The Fellows treated these events as so many ‘great electrical experiments’ then argued that such real-world experiments reinforced Franklin’s story about high points.28 But there were characteristic troubles of interpreting these experiments. If the protection had failed this might be because these rods were wrongly set up, so electrical orthodoxy was safe. But it might be because the orthodoxy was wrong and all such rods fundamentally unsafe. To solve this puzzle, Fellows had to appeal to some prior sense that they alone were masters of the facts.
Yet in the rough and tumble of society gossip and political crisis this trust was hard to win. The Society wasn’t on message. Franklin’s notions of high pointed rods and silent atmospheric discharge were backed by prestigious Fellows such as Watson, Nairne and Cavendish. But there were vocal critics inside the Society. The newspapers gleefully reported the schism. Opposition was led by the fashionable painter and theatre manager Benjamin Wilson, veteran Royal Society Fellow and pugnacious enemy of Franklin’s philosophy and politics, especially of ‘the magical point’.29 Wilson’s coterie had good connections. He was employed both by the Board of Ordnance and by the King, and won support from one of the Royal Society’s Copley medallists, the able chemist Edward Delaval, from senior military officers, noble courtiers and foreign academicians. Wilson’s experiments convinced many others that high pointed conductors were dangerous, for they would invite a lightning stroke and never safely disarm electrical atmospheres. The modern Prometheus was wrong. ‘Sharp points are put there only to invite an enemy which otherwise might not have troubled us.’ 30 Better, so Wilson urged, to build lower blunted rods much closer to threatened roofs and walls. In the midst of these histrionics the Fellows inevitably became the target of vicious satire. There were fraught votes within the Society about whether Wilson’s protests should be aired. One of his friends denounced the ‘factious illiterati’ of the Royal Society.31 According to an aged earl, ‘The Royal Society may if it pleases decide in favour of the pointed conductors, but its decisions cannot oblige me and I hope will not induce any of my friends to adopt them.’ 32
The Society’s system of experiment and trust was in trouble. Wilson and Delaval staged their own site visits after spectacular strikes to get different stories from those obtained by Nairne and Watson. Matters got serious in May 1777. The gunpowder stores run by the Ordnance Board down the Thames at Purfleet were hit by lightning. Rods installed there on the recommendation of a Royal Society committee five years earlier seemed to have failed. In the midst of the American War, British military supplies at Purfleet were no longer safe. Wilson exploited the disaster brilliantly. Supporter of metal points and transatlantic rebels, Franklin was put in the wrong electrically and politically, ‘as bad a man as he is a philosopher’.33 In summer 1777 Wilson set up a vast show to demonstrate the fallacies of his enemies. With royal funds and Ordnance Board gunpowder, he took over the Pantheon, a gorgeous Oxford Street dance hall, and installed a model of the Purfleet arsenal under a huge artificial charged cloud. The theatrical Wilson aimed to prove the dangers of elevated and pointed conductors. Many Londoners, including the royal family, watched the model’s spectacular sparks. Nairne and other Fellows tried to heckle Wilson and designed their own models of lightning and gunpowder to show the errors of his ways. Wilson’s confidants grumbled about Franklin’s ‘junto’, especially ‘setting Nairne to put you in the wrong’. Franklin’s allies launched a politically venomous attack on royal policy and the Pantheon displays: ‘those butchers sent by our infamous Ministry to exterminate the Americans are no more courageous in their hellish profession than our daring philosopher B. Wilson has been in his drum tricks’.34
For many months these tricks were satirised mercilessly in the press.35 The King reportedly ordered pointed rods replaced by lower blunt ones at Ordnance buildings and royal palaces. Some even said the fight forced the resignation of the Royal Society’s President: the Secretary of the French Academy of Sciences certainly thought this is what happened, and the resignation was soon followed by Joseph Banks’ assumption of the presidency.36 This ghastly history explains the high tension around the Heckingham story a couple of years later and the pointed political interest in its details. The Royal Society had bad form in its management of lightning strikes where pointed conductors had failed. As soon as he heard from Norfolk, Wilson again mobilised his extensive networks to make the most of the fact. He ‘began to apprehend there might be an intention to smother the matter and keep it secret from the public’.37
PROMETHEAN SCIENCE, OR HOW TO BE AN EXPERT
If the high and pointed rods had been badly set up, the Royal Society’s view would be safe. If, however, they’d been competently designed, that view would be in trouble. If the rods were plunged deep enough into damp soil or their bases covered in flood-water, the official view would have expected them to work: their failure would count as a challenge to Royal Society doctrine. So Wilson gathered stories about floods and the rods’ grounding. Royal Society envoys sent to Heckingham would seek to show the rods were not well set up and that this explained their failure. It didn’t help that the Society’s delegates were Banks’ right-hand man the suave physician Charles Blagden and Edward Nairne, Wilson’s old enemy. Wilson sent Banks details of Nairne’s ‘troublesome manner’ at the Pantheon show and support for Franklin’s doctrine. The President boldly answered that Nairne’s ‘veracity is preferred by the public and the Royal Society in general’.38
So the Fellows’ Norfolk fieldwork was initially difficult. Blagden and Nairne did their homework by re-reading reports from Purfleet and recent electrical textbooks. They needed to show the Heckingham lightning rods were badly set up. Mr Bobbitt had allegedly been at fault by letting them reach only a few inches below ground where they led into a drain ‘without being in contact with anything but air’.39 A broken rusty iron pole whose lower end was in contact with nothing but air wasn’t really a lightning rod at all. The strike hit the lead on the stable roof simply because ‘the lightning picked out the best and nearest conductors to the moist earth’.40 The Fellows seized on any story that the drains were dry even during the storm. Blagden and Nairne got the House workmen to put back everything as they recalled it was just before the strike. Three different lightning paths might explain why the rods had not taken the strike, so the Fellows accepted the story of spectacular fireballs, even if the source was a dubious female inmate. Then they toured county gentry for evidence that the electrical defence of the House of Industry was inadequate and their theory of lightning conductors safe. Wilson did the opposite. He contacted Norfolk friends for signs the rods were in a good state, drenched with drain water and well maintained. ‘Have you been able to learn from anyone of good judgment how high the black cloud was at the time it hung over the House? And whether any of the flashes of lightning were seen to make towards the pointed conductor?’ 41 Wilson got Gamble to build a model of the House like the one of Purfleet, then showed it to the King and the Ordnance Board. He reckoned it showed the high pointed lightning rods had failed. If so, Royal Society doctrine had failed too.
The metropolitan outcome of the Heckingham inquiry was managed by Nairne, Blagden and Banks. The report they sent the Ordnance Board in February 1782 showed the imperfections of the Norfolk lightning rods and strengths of the received theory of their behaviour. It was publicised by the Society and copies sent to foreign papers.42 With the status of the Fellows and the select group they interviewed, they could secure agreement in the capital. Back in Norfolk things were less sure. In the 1780s ‘there was more mind afloat in Norwich than is usually found outside the literary circles of the metropolis’.43 The Fellows’ informants were gentlemen with their own views of electricity and lightning. None lined up in an orderly fashion behind Nairne and Blagden. The Heckingham governor Samuel Cooper insisted his House’s rods were well earthed, ‘nothing wonder
ful or even extraordinary’ had happened, and complained to Banks that ‘some of those who spend their time chiefly in making of experiment are too apt to treat those who do not with a dogmatism bordering upon contempt, would the latter venture to deduce by the legitimate principles of logic a plain and obvious conclusion from the experiments of the former’.44 While Cooper questioned London experimenters’ authority, Gamble had his own story of how electricity worked. Along with his model of the House, he made a diagram of lightning discharge. He insisted against Nairne that the rods were perfectly grounded, ‘these pointed rods were the cause of the stroke’s taking place in their vicinity’, and couldn’t accept the Fellows’ notion that the House was struck because the rods were surrounded by insulators. ‘For God’s sake, what should it be connected with so proper to keep the effect of the storm from entering the House!’45 According to Mr Gamble, the Society’s story simply didn’t make sense.
