Equinox

towards the towpath that ran parallel to a tributary of the River Cherwell.

The path down to the river was slippery and Philip took the steps slowly. The rain started up again, and ahead of him he could see the murky grey river. About ten yards away stood a bedraggled-looking group — two uniforms, Monroe with his back to the path, and a sergeant holding an umbrella over the head of the DCI. Further off, two CSI guys were walking away towards a house that extended out on stilts into the river. The rain grew heavier and Philip was tempted to run back to the car for his umbrella. But just at that moment Monroe spotted him.

'Mr Bainbridge. Alone today, are we?'

Philip sighed, put his hands in his pockets and risked a brief smile.

'Well, we have a real doozy for you this morning. Better prepare yourself

'What? Worse than last night?'

'Depends how squeamish you are. Woman out jogging found her about seven o'clock. Forensics tell me she's been dead between four and six hours. Follow me. You're going to have to work to find a suitable angle — and watch yourself

Monroe picked his way carefully along the path. Some plastic sheeting had been draped over the branches of a tree on the bank and a single floodlight was shining onto the lapping river under the lowest bough. Just behind Monroe, Philip could see the red stern of a punt. As he took in the full horror of the scene, he felt his stomach lurch.

A young woman was half-sitting, half-lying at one end of the boat. She was dressed in jeans and a T-shirt and was staring at the bank with sightless eyes.

She looked completely drained of blood. Her arms were spread wide and her left hand hung over the side of the punt. Streaks of blood could be seen on the inside of her arms and across her shoulders. Her eyes were open, but what had been their whites were almost completely red: the blood vessels had burst. Over her eyes lay. a slimy film that dulled the colour of her blood. Her throat had been cut and the top of her head had been removed cleanly, expertly, a hemisphere of bone and scalp sliced away. Where her brain had once sat there remained nothing but a red and black bowl. In a few places the dead tissue had been scratched away to reveal startlingly clean white bone.

Inside the woman's head, a highly polished silver coin caught the light: a silver twin to the gold coin that Philip had seen in Detective Chief Inspector Monroe's gloved hand the night before.

Philip turned away and took a couple of deep breaths.

'I'll give you a few minutes,' Monroe muttered, climbing back to the path. 'But I'll need the pictures at the station within the hour.'

Philip wasted no time in setting up his shots. He knew from long experience that this was the only way he could deal with these situations. The more horrible the images that lay before him, the more intently he had to disconnect, to go into a robotic state where he simply did his job and forced himself to become blind to what lay beyond the camera's lens.

He took a series of shots from the prow of the punt: some close-ups using the telephoto attachment and a couple of wide-angle pictures. Then he walked along the bank, and took some shots side-on before crouching close to the stern where the boat had lodged against the bank, and where the most horrific images could be captured, digitised and stored on a chip in his camera — a human life reduced to pixels.

It wasn't until Philip had clambered up the bank, given the two uniforms left at the scene a careless wave and turned the corner into Cave Street that he realised how much his hands were shaking. Reaching the car, he was about to open the boot when a wave of nausea hit him. He vomited into the gutter and watched the bile wash away in the speeding rainwater flowing down the street.

Chapter 8

London: October 1689

Gresham College in the heart of the City was an oasis amidst the squalor and filth of London. Although the buildings were old and crumbling and there had been increasingly vociferous calls to redevelop the site, it possessed a tranquillity and a mesmerising charm that belied its sorry physical state. Its appearance was also remarkably understated for the regular meeting place of some of the greatest minds of this or any other age.

The Royal Society had been founded almost thirty years earlier by Christopher Wren and a few close associates. It had quickly grown, gaining royal approval and with it a name. But in recent years that name had diminished in stature. Part of the problem for this illustrious gathering of men was that they could never settle anywhere for long. Their original home had been here within the faded grandeur of Gresham College, but after the twin tragedies of the terrible plague of 1665 and the Great Fire the following year the college had been requisitioned by the City merchants whose own premises had been destroyed. Then it was transformed into a temporary Exchange while a new financial centre was under construction. The Royal Society, with its books and its experimental apparatus, its sextants and charts, its telescopes and microscopes, had been offered the library of Arundel House by the owner, the Duke of Norfolk. This was located a couple of miles to the west, in a street just off the Strand. Here the Society had continued to meet for a while to discuss the latest scientific ideas and to conduct scientific investigations organised by its Curator of Experiments, Robert Hooke.

While it was ensconced in Arundel House, the society started to publish books, including Hooke's own Micrographia and John Evelyn's Sylva , and, keeping up a tradition begun by the earliest scientific societies in Galileo's Italy, it also published a journal, the Philosophical Transactions , in which there were descriptions of discoveries and reports of lectures and the works of the Society's members. But then, after a few years in Arundel House, they had been obliged to start meeting again at Gresham College, in rooms put aside for the purpose by the influential Hooke, a Fellow of the college.

Although Isaac Newton knew all this, as he entered the main quad of Gresham College at two minutes before six, the darkening western sky drenched in orange, he felt almost no affinity with the Society that he had joined as a young man of twenty-nine, seventeen years earlier. In spite of the fact that the illustrious Fellows had published his Principia Mathematica , a book that had made him the most important scientific figure in the world, during the past decade he had attended the Royal Society no more than a handful of times. He could consider no other member his friend, and he was barely able to extend a degree of trust to just three other figures within the scientific community. The elderly Robert Boyle was one, the young genius Edmund Halley was another, and the third was the man who had persuaded him to leave his cloistered world of Trinity College, Cambridge to visit London this evening: Christopher Wren.

However, the main reason for Newton's conspicuous absence from Society meetings had been the even more conspicuous presence of Robert Hooke. The man had become a bitter enemy almost as soon as they had met and when, in 1676, the Society members had elected Hooke to succeed Henry Oldenburg as Secretary, Newton had offered to resign his own Fellowship. Persuaded to continue by those who saw him as a man too valuable to lose, he had finally capitulated. But he had vowed to attend meetings only when it suited him to do so.

Newton understood that people considered him to be a difficult man. He was undeniably someone who shunned the company of others and he cared nothing for the effect this had on the sensibilities of those around him. He was completely self-contained and proud of it. He needed no one, but people needed him and they would grow to rely upon him increasingly in the future, of that he was sure. It was sentiments such as these that had kept him in his laboratory in Cambridge. The only man in whom he had confided a little was John Wickins, a scholar of theology and his room-mate for more than twenty-five years. But, Newton ruminated as he crossed the quad and passed under an archway to turn left into a stone passageway, even Wickins understood only a fraction of what was going on in Newton's mind and almost nothing about what actually happened in the laboratory so close to his own bedchamber.

As he thought about this, Newton cast his mind back some six months to the morning when he had been forced to change the direction of his investigations. It was the morning when he had learned of the ruby sphere. It was his greatest secret and he could discuss it with no one. For days and nights he had done little else but ponder the meaning of the message left by George Ripley. He had scoured every text in his possession. He had returned to