retrieve my son, as soon as I’m satisfied with what I know, or don’t know, if it comes to it. I fear that Narbondo will effect an explosion in London soon, probably catastrophic.”
“Tuesday, we believe,” Jack said, having returned to them. He handed St. Ives the sheaf of papers they’d taken from de Groot. “Tomorrow, perhaps, or a week hence.”
“Tomorrow, I’d guess, from the eagerness of their work,” St. Ives said as they walked over the dunes. He wondered if, indeed, the day was at hand. If it were, then the two men they’d seen carrying Greek fire along the embankment this morning were only a small part of things. It was singularly impressive that they’d blown up the Fleet Sewer, but it must be a meager display indeed if Mother Laswell’s fears were remotely sensible. Surely, he thought, there was no time for Narbondo to be contriving ornate new skulls for the Customer if in fact he looked forward to opening a door to the afterlife on the morrow. Narbondo already possessed the Aylesford Skull, his open sesame, as it were. Perhaps kidnapping Eddie had everything to do with revenge after all, revenge and profit – the attempt at extorting the heavy ransom from St. Ives, while taking fees from the Customer – playing them both false and luring St. Ives into the Cliffe Marshes into the bargain, thus getting him out of London. Any or all of this might be the case. Or none of it.
He studied de Groot’s papers while awaiting dinner, neither surprised that Moorgate should be the infamous Customer, nor that he was working toward some nefarious political end. Regicide, however? Was the man so far gone in megalomania that he would dare to murder the Queen? Narbondo would seize at the chance to manipulate such a man.
Dinner appeared, arriving in several removes, the garlicky fish cooked in wine and herbs and finished with butter, the lamb ragout redolent with cloves and allspice and cinnamon, and bottles of India Pale Ale brewed by Uncle Gilbert’s particular friend in East Sussex. Tubby and Gilbert mopped up the gravy with chunks of bread, Gilbert reporting on bustards, of which he had seen not a one, although they had recorded thirty-four other species of bird, having shot and eaten three of them. Their hopes were far from dashed, however, for they’d spoken to a man who claimed to have seen a fifty-pound bustard in an open meadow. The man hadn’t been quite sober, perhaps, but liquor didn’t turn a man into a liar by any means, Uncle Gilbert pointed out. The opposite was more often true. There was of course some chance that he had seen a particularly fat lamb…
Gilbert intended to stay through the summer, birding being his great passion, and the encampment having come to seem like a second home. St. Ives only half-listened, and as for the food, he ate but scarcely tasted it, his mind distant. He considered the mysterious Guido Fox, the business of the dust flying along with the martyrs. He thought of Shorter’s palm house, the contraband coal, the phosphorous and gunpowder and lead bullets in Narbondo’s lair in the rookery, the photographic plate with Eddie’s image on it, which he swept out of his mind immediately now.
“What do you know of coal, sir?” he asked Uncle Gilbert, who had fallen silent while helping himself to another slice of fish.
“I know the price of it by the ton,” he said, “and the relative merits of hard and soft varieties, but only when it comes to smelting. My firm manufactures railway iron, you know, near Blackboys. Not my firm any longer, of course, in any real sense of the word. I sold the vast majority of my shares in the spring. I’m a free man now.”
“And a rich man,” Tubby put in.
“Quite right,” Gilbert said. “Buckets of the stuff. Croesus ain’t in it. I enjoy my comforts, Professor.”
“I’m quite enjoying them myself, sir. Dangerous, is it, coal? Flammable, of course; but explosive?”
“Can be. Depends on particle size and how it’s treated.”
“Doyle, you were telling us about your voyage aboard the
“We suffered a coal fire in a storage bunker,” Doyle told them, leaning forward. “We were north of Madeira, coming home. The captain was opposed to flooding the bunker due to the weight of the water, which would make the ship unwieldy, what with the swell running high, so he elected to seal the bunker to reduce oxygen. The fire smoldered hot, though. At night the hull plates glowed red, and the boats were maintained at the ready. We had a cargo of palm oil aboard – highly explosive.”
“There’s a vast amount of dust in a coal bunker, of course,” said Gilbert, shaking his head, “and that’s the problem, isn’t it? If the bunker was opened and the ocean breeze allowed to suspend the dust, it might have gone very bad, sir, very bad indeed, no matter how many boats were readied.”
“Tell me specifically about such explosions, if you please,” St. Ives said.
“It’s an elementary business, sir,” Gilbert told him, “although I don’t mean to come it the school teacher.” He drank half a bottle of pale ale then, at a draft, and gasped afterward.
“I’m in need of a school teacher,” St. Ives said. “Tell away.”
“Well, sir. I’ll tell you that five things are required to effect an explosion: a sufficiency of coal dust – less than you’d suppose – the suspension of the dust, along with oxygen, heat, and confinement. In the case of Mr. Doyle’s ship, they were all on hand except the suspension. The coal would burn, low and hot, but without suspension there would be no explosion no matter the temperature. Hence the Captain’s sealing of the bunker against the breeze. It reduced the oxygen, certainly, but the oxygen was far less dangerous than a gust of air.”
“And all coal dust is equally explosive?” St. Ives asked.
“No, sir. Anthracite dust not at all. It’s a matter of what they call the volatile ratio, do you see? Calculating it is a simple business, but suffice it to say that it must be bituminous coal or something softer to create a dust hazard, but only if the particle size is tolerably small.”
“Lignite coal?”
“Quite explosive, especially if it’s dry.”
“The smaller the particle the more explosive, I take it.”
“Just so, for two reasons. The small particles are of course easier to suspend, and the explosion requires less heat, which transfers far more quickly through fine dust.” Gilbert took another hearty swallow of his ale, wiped his mouth with the back of his hand, and set the bottle down.
“It must take a great quantity of dust to set off an explosion of any consequence,” Jack said. “Tubby pointed out to us that Guy Fawkes had hauled a dozen barrels of gunpowder into his basement beneath Parliament. Surely gunpowder is far more explosive than powdered coal?”
“Don’t believe it for a minute, sir,” Gilbert said. “Guy Fawkes was a fool, which is why he was hanged.”
“Not hanged,” Doyle said. “As I recall he leapt from the scaffold and broke his neck.”
“My point is proven in either event,” Gilbert said. “Here’s the thing. If there was enough dust on the floor of this coal bunker so that footprints were clearly visible in it, there was enough dust for an explosion were the dust suddenly suspended, although perhaps not a terribly intense explosion. This is a matter of what the experts refer to as the ‘minimum explosive concentration,’ although it’s not a fine science, sir, especially in a large structure. In a coal bunker it’s much easier to calculate. To a point, the more dust, the greater the blast. Beyond a point, the dust has a smothering effect. If there was coal gas present also, as there often is, the result would be extraordinary.” He thrust a piece of fish into his mouth at this juncture, immediately found a bone, and spat the bone and the piece of fish out into the grass. “Pardon me,” he said, “that ain’t manners. Come, what more do you need to know, Professor? I’m quite enjoying this, you being the student and me the tutor, ha, ha.”
“As for heat…” St. Ives began, thinking of Shorter’s palm house, with the coal oil heaters and lamps.
“For dry, finely corned lignite coal, thoroughly suspended and in sufficient quantity,” Gilbert said, anticipating him, “a mere spark might set it off. Certainly an open flame would bring about an explosion. The danger was very great in Mr. Doyle’s ship, for there was no doubt red-hot dust on the floor. The mere act of suspension would have ignited it, the heat being already present.”
St. Ives stood up and nodded his head, having made up his mind and feeling the day slipping away from him. “Gentlemen,” he said, “I believe I see the way of it now. It’s my belief that Narbondo and Lord Moorgate intend to create an atrocity at tomorrow’s ceremony at the Cathedral of the Oxford Martyrs by pumping it full of suspended coal dust and igniting it, either with Greek fire or by some other source of heat. Hasbro tells me that the Queen will be on hand, along with no end of dignitaries and God knows how many thousands of onlookers. I doubt very much that we can stop it ourselves, and Narbondo’s motivation – you’ll have to take my oath on this – is so very implausible that it would be folly to attempt to persuade the police or the army to act. In order to avoid utter defeat I intend to attempt to rescue my son immediately, and let the devil take the hindmost. Once again, anyone who is with me is welcome. Duty to the Crown, however, would require that you leave for London post haste to attempt to prevent the debacle, if in fact I’m correct.” St. Ives moved immediately to collect the weapons that he and Hasbro
