by Stuart Clark
Hooke squeezed her hand. Something was taking hold of his senses. The world seemed to be twisting around him. Blinking did not help clear his vision. It was similar to the confusion he had suffered after being attacked near the Letter Office, but this time there had been no impact. Nevertheless his mind had deserted him. He could hear Grace’s voice but not make out her words. He could tell that she was agitated but could do nothing to reassure her; his voice had left him. He staggered into something hard – a wall? It was difficult to tell which motions were real and which imaginary. Whatever had gripped his mind had taken complete control.
Now he could hear Grace shouting for help, but he was utterly unable to respond. He concentrated on the solid mass of wall pressing against his back. Having lost all sense of position, he could not be certain whether he was horizontal or vertical.
The night was a tempest of colours, the kind of mess that he had seen Grace make on a painting palette once when she had lost her temper. He watched them swirl around him until gradually things cleared. He was upright, leaning against the wall. Grace was approaching at a run with a gentleman in tow.
Hooke raised his hand to halt them. ‘I feel quite well again, thank you.’ A sense of elation and a strange clarity of thought entered his mind.
‘You’re quite well, sir?’ asked the gentleman.
Hooke nodded. Puzzled, Grace thanked her helper and made to put an arm around his shoulders.
‘There will be no need for that,’ he said mildly, tucking her arm through his.
‘You scared me. Are you sure you’re quite recovered?’
Hooke nodded. ‘Whatever it was has passed.’
They set off.
‘I want to thank you for taking me out tonight.’ A small laugh escaped her. ‘Why did you never marry? You’d have made someone a good husband, you know.’
‘It’s against the terms of my employment at Gresham. Besides, wives are a distraction.’
‘I think I’d have liked marriage, and a family.’
‘Galileo’s daughter Virginia never married. Instead, they remained constant companions.’
She dipped her head to look at him through her eyelashes. ‘Is that my role in this: daughter to your Galileo?’
‘Hardly. She became a nun.’
Grace giggled, and the sound of it charged him with longing.
‘I love you,’ he said, suddenly serious.
She pulled him a little closer and they walked on.
14
Winter fell upon the city. The first bite sent carriages and people slipping across icy puddles. The second blanketed the streets in snow, stifling the sounds and robbing them of smells. The initial covering was pristine, but as a hundred thousand home fires began burning in grates across the capital, so the smoke mingled with the clouds to create a sulphurous cloud, staining the snow to bile-yellow. The heavy cloaks and jackets that people had taken to wearing transformed the population into black ghosts, floating through the muffled city.
The Thames froze gradually, cracking and splitting at the margins until it came to a vitreous halt. Incoming carpenters and stallholders went to work building counters and booths to transform the stilled river into London’s latest, albeit temporary, thoroughfare. The wherries were fitted with skis so that the boatmen could drag their passengers across the ice instead of rowing them through the water. The crowds loved it, picking their way with care around the bull-baiting and the young boys who slid along the frozen surface, all the while trying to ignore the numbing cold that crept upwards.
On this particular evening, Halley was on his way to Garraway’s coffeehouse. He hurried through the tainted snowfall, long cloak rippling. The excitement of the Frost Fair had been eclipsed by the frustrations he had felt with his mathematics today. He had spent the day huddled in his study, shivering against the air that rolled off the window. He had chased numbers across the page, formulating and reformulating but never making any progress. Now he had to exorcise the frustration before it gave him another sleepless night.
Garraway’s coffeehouse was a long hall, full of aromatic warmth and the hubbub of conversation. The well-heeled squeezed on to wooden benches alongside those on the make. Some chatted, always eager for a new piece of information or the chance to turn a profit; others read the broadsheets that littered the place, though they contained little more than propaganda of one sort or another.
Halley placed a penny on the bar, where a woman with rouged lips and a gigantic wig stood among a castle of pots. The size of her wig was matched only by her impressive cleavage. She did not look round, but set down her cloth and indifferently handed over a shallow bowl at the sound of the coin.
‘Thank you, Rose,’ acknowledged Halley in his baritone.
Her head turned immediately. ‘Well, Edmond Halley. Haven’t seen you round here for a while.’
‘I’m a married man now.’
She pulled a face. ‘What can I do for you tonight?’
A smile tugged at his lips as he remembered the old days. ‘What indeed?’ He leaned towards her, lowering his voice. ‘Alas, tonight I am here on a matter of some urgency. I’m looking for Robert Hooke.’
She pointed to the far corner. ‘He’s over there.’
‘Thank you, Rose.’
‘Perhaps later?’ she called, raising an eyebrow.
Halley winked, instantly regretting the gesture. That was how you used to behave, he scolded himself. He stopped to fill his bowl from the black cauldron suspended over the fire, then made for the large gathering near the far corner of the room. Sure enough, Hooke sat at its focus.
Hunched in his seat, his leathery skin illuminated by the ruddy glow of the fire, Hooke was a shaman. His yellowing eyes held a group of men spellbound. Some stared, others nodded, and shoulder to shoulder they hung on his words as if they were an incantation. Tonight, the shaman’s tale was of orbits.
‘Kepler showed us that there is no mystery to the movement of the planets. Each heavenly orb follows an elliptical path around the Sun, each path as individual as the ugly faces I am looking at tonight.’ Hooke swept his eyes around the crowd, relishing the smattering of laughter.
‘Watch!’ He overturned one of the broadsheets and dropped on to it a circle of twine from his hand. He fitted the parted arms of a metal calliper into the twine and, with the other hand, hooked an inked quill into it. Pulling the string taut with the pen, he traced a curve, allowing the tension of the string to guide his hand into an ellipse. He removed the apparatus from the paper and pressed the quill into the point left by one of the calliper’s arms. ‘The Sun sits here, at a focus around which every planet follows an elliptical path of some description.’
‘But why an ellipse?’ called one of the crowd.
Hooke pointed at the man as if pressing a button. ‘That, sir, is the question of the age. Why the ellipse? Kepler found another clue: that a planet moves faster through its orbit when it is closer to the Sun. So whatever power the Sun exerts to move the planets must diminish with distance. But how does this force communicate itself across space?’ Hooke pointed at the man again. ‘Say I wanted to move you, sir. How would I accomplish that feat if I am fixed to this spot and cannot approach you?’
‘I would say it’s impossible, so long as I stay out of your reach.’
Hooke gave the man next to him a forceful shove, spilling the man’s coffee and propelling him into his neighbour, who fell sideways into his neighbour. In a second, the momentum had reached the questioner, who rocked sideways.
‘Mechanics, gentlemen,’ said Hooke in triumph. ‘It’s the key to understanding how forces transmit themselves. They must travel through an intervening medium. For gravity, the medium is a substance not found on Earth: the ether.’
A member of the crowd called out, ‘But what of the comets, Mr Hooke? Do they truly bring evil?’
‘They are most certainly not evil. They’re natural objects, not omens.’
‘But one did appear over the city before the pl
ague,’ said another of the audience.
Hooke sighed. ‘How then shall we measure their wickedness? There is no uniform lag of time between their appearance and calamity. And why did we not see a comet before the Great Fire, was that not terrible enough to warrant an omen? The world is a mechanical place. If the comets truly brought evil, they would do so without exception, just as a wheel always turns when pushed.’
Halley could contain himself no longer. He called out in a disguised voice, ‘I’ve read that comets formed in the Earth’s own airy heights, condensed from the ascending vapours of human sin and wickedness. And that this poisonous stuff then rains back on to us, forming all unpleasant phenomena, such as diseases, sudden death, bad weather . . . Frenchmen.’
Hooke swung his head in search of the heckler.
Halley nonchalantly curled a strand of his long dark hair behind an ear.
The two men eyed each other.
‘You!’ spat Hooke.
‘Have you still not forgiven me for that business with Hevelius?’
‘You sided with a foreigner against me.’
‘I worked with him, used his quadrant. I know his methods. You just dismissed him out of hand.’
‘It’s not the only thing of his you handled, from what I hear.’
Halley looked to the ceiling. Around him, Hooke’s impromptu audience began to drift away. When he looked down again, Hooke was gathering his things.
‘I have to leave,’ said the Gresham Professor.
‘Not yet, your rendezvous with Sir Christopher isn’t until nine o’clock.’
Hooke’s gaze sharpened.
‘I stopped by your rooms,’ explained Halley. ‘Grace informed me that you’re to meet with Sir Christopher in Jonathan’s coffeehouse at nine o’clock.’
Hooke stuffed the loop of twine into his pocket and rose from the table.
‘Let me accompany you,’ said Halley.
‘You’re wasting your time.’ Hooke pushed through the crowded room and disappeared outside.
Halley sighed, then hurried after him. Just ahead of him, Hooke moved in and out of sight in the thronged alleyways.
‘Robert, I must speak to you. Only you can help me.’
Hooke did not stop, but there was interest in his voice. ‘How so?’
‘I wish to talk of gravitation.’
Hooke paused before the coffeehouse entrance and turned to Halley. ‘What about it?’
‘Let’s talk inside, it’s a bitter night.’
‘Pay my entry and you buy yourself some time.’
Halley reached for the door. ‘After you, sir.’
‘Gentlemen, I have been wrestling with a simple but vexing question,’ said Halley once they had squeezed around the table that Wren had been guarding. ‘Night after night I study the Moon. But what keeps it suspended in its orbit? We all agree that something called gravity holds us to the Earth, and makes things fall to the floor. So, if this gravity extends into space, what prevents the Moon from falling on our heads?’
Wren tapped the table with his finger, as if bringing a meeting to order. ‘Gravity must decrease with height. So by the height of the Moon, its grip is so light . . .’
Halley stopped him with a shake of his head. ‘Even if the grip is light, it will still attract the Moon. The closer the Moon gets, the more it will be pulled and the faster it will fall until . . .’ Halley clapped his hands together.
‘Then a balance of two forces, one pulling the Moon down, the other pulling it out into space.’
‘Aristotle’s opposing forces of gravity and levity? That is some old thinking, to be sure,’ said Halley.
‘Are we so modern that we now reject all old ideas out of hand?’ asked Wren.
‘Indeed we do,’ said Halley, ‘unless we can prove them. Besides, that would make the Moon hover rather than orbit. There must be something else at work that makes the Moon travel around the Earth but not fall to it. For the planets orbiting the Sun, too . . .’
Hooke was smiling to himself.
‘Robert?’ asked Wren. ‘Do you have something to say?’
At length, Hooke spoke. ‘I already have the solution. Gravity diminishes with distance in the following way: double the distance of two objects and the gravitational force between them quarters. Triple the distance and gravity falls by one-ninth.’
‘An inverse square law,’ said Halley.
‘Exactly.’
‘But that doesn’t solve the problem of what keeps the Moon in orbit.’
‘There’s another force – but not pulling outwards. It tries to push the Moon along at right angles to the downward pull of gravity. Together, these two forces drive the Moon into its perpetual orbit around the Earth. It’s similar to the way water stays in a bucket if the vessel is swung sufficiently fast above one’s head. Just as the water defies the pull of gravity because of its motion, so too does the Moon.’
Halley searched Hooke’s face for some hint of jest. ‘How do you know this? Did Newton reply to your letters?’
Hooke looked insulted. ‘No, he did not.’
‘Of us all, he has the mathematical acumen to perform the analysis,’ said Wren. ‘From what I hear of his fluxions-and-fluents technique, it would be the perfect mathematical tool to use.’
Hooke stabbed him with a look. ‘How many times must I tell people? Newton has given up on philosophy.’
‘What happened to that little telescope he invented, the one that used mirrors instead of lenses? Didn’t he present it to the Society at the same time he came to talk about colours?’
‘It was impractical,’ grumbled Hooke. ‘The mirror tarnished every few months and needed polishing. Now he keeps his mathematics secret. He’s of no help to us. There’s no need for him to start meddling in any of this. Besides, Leibniz is beginning to publish his version of the fluxions, so we don’t need Newton.’
‘The Society needs as many new members as it can get. As it stands, we’re ailing,’ said Wren.
‘We’re a little slow on progress, that’s all,’ said Hooke.
‘There are those close to Charles Rex who openly wonder why he continues to support us. But, if we could discover something – something useful – we might silence our critics,’ said Wren. ‘Or perhaps our little experiment with natural philosophy is over – perhaps we have plumbed it for all it has to offer.’
‘Never! The world is there for us to measure. We have barely begun,’ said Hooke. ‘But we don’t need Newton; I have pressed on alone.’
‘Can you prove that elliptical orbits follow from an inverse square law of gravity?’ asked Halley.
‘Yes. Kepler’s laws proceed from three suppositions.’ Hooke counted them off on his crooked fingers. ‘One, all celestial bodies have an innate ability to attract others. This gravity also prevents such bodies as the Earth from falling to pieces. Two, a body in motion will continue travelling in a straight line until some other power deflects it, whereupon it will describe a circle or an ellipse, or simply a part of a curve before it moves out of range. And three, the attractive power of an object diminishes with distance. The further away something is, the less powerfully it is affected. The decrease – as I have said – is in the inverse proportion to the square of the distance.’
‘But can you back this up with a solid chain of mathematics, as you told me that Bonfire Night you had asked Newton to provide?’
Hooke looked into his steaming drink. ‘Of course.’
‘Then show us,’ said Wren.
‘Yes, show us,’ said Halley. ‘The solution would take us towards the perfection of astronomy.’
Hooke continued to contemplate his drink.
Halley exchanged a glance with Wren, who rolled his eyes.
‘I will give you forty shillings if you show us the proof,’ said Wren.
Hooke blew out a derisive breath. ‘Hardly a prize worthy of winning.’
‘Then think of the prestige,’ said Wren.
‘There are too few capable of
understanding its importance, and even fewer who could make use of such knowledge,’ said Hooke.
‘Maybe so, but what do you gain from withholding it?’ asked Wren.
Hooke looked up. ‘Respect. When others have tried and failed, then they will appreciate its true value.’
‘Then let us set a deadline.’ There was impatience in Wren’s voice. ‘Say, two months from today. If no one has claimed the forty shillings by proving that elliptical orbits follow from an inverse square law of gravity, then you will enlighten us all.’
When Hooke failed to comment, Wren leaned towards Halley and spoke in mockingly conspiratorial tones. ‘If still the solution is not forthcoming, one of us will have to visit Cambridge and plead with Newton to save us.’
Hooke grimaced at Halley’s hearty laugh.
Later, Halley gathered his cloak and rose from the table. ‘Gentlemen, I thank you for your time but I must start for home.’
‘Will you not stay? The hour is only ten. Where is your passion?’ Hooke called after him.
‘There is passion aplenty in me, which is why I must bid you gentlemen good-night and find me a carriage back to Islington and my wife.’
As he neared the door a fresh-faced man with a chin sprouting inch-long blond whiskers blocked his way. The young man’s eyes were unusually large, as if startled, and of the palest blue. He spoke, stumbling over his words. ‘I would speak with you on a delicate but important matter.’
‘Who are you?’ asked Halley.
‘Hugh Speke, a lawyer at Lincoln’s Inn Fields.’
‘Lawyer or student?’
‘In my final year of study.’ Speke’s voice quickened but remained quiet. ‘I wish to speak with your father.’
Halley said nothing.
Speke whispered, ‘It concerns the Earl of Essex.’
‘My father has no link to the Earl of Essex.’
‘He was at the Tower the day the Earl was murdered. He attended the Duke of York.’