It finally occurred to him to look at Isaac to see how the arch-Alchemist reacted to this glimpse of the Art writ large. Daniel saw in Isaac’s face neither fascination nor disgust but a kind of pensive bewilderment: the look he got when he was drawing connexions in his mind that were beyond Daniel’s powers. But he looked suddenly at Daniel and remarked, “Clarke’s house.”

Which was a reference to a thing he had taken Daniel to see fifty years earlier, on a visit to Grantham, Lincolnshire: an apothecary’s house where Isaac had boarded as a schoolboy. Clarke had dabbled in Alchemy and had filled a side yard of the house with wreckage of his experiments. It was much smaller than what they had just seen, but to young Isaac must have seemed as large, and as glamourous with hazards, and as seething with mystery. In the half-century since, all things Alchemical had become familiar to Isaac; but what he had just seen must have jolted him with the same emotions he had known as a boy making illicit forays into Mr. Clarke’s laboratory.

For Daniel’s part, he wanted to loathe what Jack had made of this good old farm, and to be outraged, and to hate Jack all the more for it. But none of these feelings came to him. They would never come, because Daniel had already seen in Devon the works of Mr. Thomas Newcomen, which were like a harbinger of this thing. Or perhaps the Engine for Raising Water by Fire, and Jack’s phosphorus-mill, were both harbingers of something else, which he could scarce picture in his mind-and scarcely wished to. He had once said to Mr. Threader, in a very self-righteous way, that England did not need Slaves, if she could learn to make Engines, and that Engines, being clever, were a more English sort of thing than toiling Negroes; but now he was beginning to think that he ought to be more careful of what he wished for. The first phosphorus laboratory ever made-that of the Alchemist Heinrich Brand-had been so clever that it had inspired Leibniz to write a poem about it. But Daniel could see from the look on Leibniz’s face that he’d be writing no poems about this place, unless it was a supplementary Canto of Dante’s Inferno.

They debarked from the carriage, for the horses would on no account draw any nearer to the noisome Works. They knew that the dog was tethered, for they had nearly run over it, and they knew that no humans would be about, because who could or would sleep atop such a hell-mouth? So Newton, Leibniz, and Waterhouse strode rather than crept toward the Factory, and when they heard hoofbeats coming up behind, none of them paid it much mind, knowing that it was the young Mohawk who had been detailed to keep an eye out for them.

The last breaths of the fog had at last blown off from this hilltop, though the low places among the downs were still gloomed under fat gray rivers. One could see ten miles from this place-and anyone save a Natural Philosopher would turn his back to the ugly scene in the center to enjoy the prospect. But these men, who thought nothing of dissecting a beautiful corpse to examine a necrotic ulcer, had eyes only for the phosphorus-works.

The compound was ringed by an old hedgerow that had been viciously trimmed back by its new tenants, and cut down to the height of a man’s mid-section. Newton, Leibniz, and Waterhouse passed through a gap where it was pierced by a little side-track, and the Mohawk, who was angling in from another direction, jumped it easily on his mount, wheeled round, and trotted toward them. Waterhouse, well knowing his place, assumed the tedious duty of talking to the rider so that the great ones’ observations would not be disturbed. “Never mind what orders you have been given,” said Daniel, “this place is the objective of the day-it is why we have all come here.”

“Shall I go and summon others?”

“I do not think it necessary-they’ll find us anon.”

“I meant, sir, in case we should meet with resistance.”

“There will be none,” said Daniel, “except for that!” And he pointed toward the dog, who was sprinting for them.

It turned out that this animal’s tether was very long indeed, so that it could range over the entire hilltop, provided it did not commit the classic error of getting the rope wound around anything-and it was one of those dogs who was clever enough to avoid that. Having (or so it imagined) chased off the carriage of Newton, Leibniz, et al., it had found employment on the opposite side of the compound, barking at some untoward noises. But now it was coming for them, angling in on their larboard quarter. It faltered as it perceived a choice between going for Newton and Leibniz-who were several paces ahead-or Daniel and the mounted Mohawk. Wisely, it chose the former. Newton and Leibniz, so different in matters of high philosophy, were absolutely the same when it came to being chased across a farm-yard by a huge ravening mastiff. They cheated to the right, and got up against the hedgerow, prepared to clamber over it if they had to-but this was a last resort, at their age. Then they hustled forward, hoping to get out of the tether’s fatal radius. But that tether simply kept uncoiling-just when it looked as if it were about to jerk taut, fresh miles of it would appear, as if by some conjuror’s trick. Newton almost tripped over something, and Leibniz bent down and picked it up: it was a long wooden paddle, chymically gnawed and stained, its handle snapped off at one end, but still a fathom long. For they had drawn nigh the boiler where such implements were used to stir and test the thickening coction. Leibniz waved this find around, sending a message that the dog collected instantly; it broke off the frontal assault and shifted fluidly into a feinting-and-lunging style of flank-attack. Daniel caught up with the others about now, and, passing behind Leibniz’s defense, went to haul Isaac Newton up off the ground. Meanwhile the Mohawk had ridden up behind the dog and was shouting to draw its attack: a plan his mount well understood and little favored, so that this rider must devote all his powers to managing the mental states of the dog on one hand and the horse on the other.

Isaac was down, not because he had tripped, but because he had gotten interested in something. He held out his hand. A reddish nodule lay in the middle of his palm. “Behold,” he announced, “Jack has learnt the art of making red phosphorus. It is scattered all about.”

“That would be the source of ignition for the Infernal Devices, then,” said Leibniz over his shoulder. He was still en garde with the paddle, protecting the other two, who were crouched behind him at the base of the hedgerow. But this was less and less necessary, as the Mohawk now had the dog’s undivided attention. The horse kept rearing so that it might bring down its hooves on the mastiff’s head.

The rider had his pistol out.

“Hold your fire, sir,” said Daniel, who long ago had grown sick of seeing dogs killed in the name of Natural Philosophy. He stood up, and pulled Newton to his feet. Something in that word fire was troubling him.

“Hold your fire!” cried Leibniz, who had glanced down to see red phosphorus all over the ground. But the Mohawk heard them not. The dog’s tether had come round to touch the horse’s hind legs, and made it panic. The cavalryman leveled his gun at the dog. Leibniz whirled about, turning his back on what was about to happen. Seeing the others a few paces away, side by side, he spun the paddle round to make it horizontal, and held it before him at chest height. Then he hurled himself forward. The implement caught Daniel just below the collar-bone and forced him back until the stiff old vegetation of the murdered hedgerow chopped him just below the buttocks. His last clear impression was of a bolt of fire jerking out of the muzzle of the pistol. Then the sky spun round him-a Ptolemaic illusion, of course, as in truth he was executing a backward somersault over the hedgerow. He-and Newton beside him-tumbled all the way over on the other side, and ended up sprawled face down in the lee of the hedge. The backs of his calves were being broiled by a sea of white flame that had reached over the wall like sunrise.