“You lost a ten in there someplace,” he said, “but I don’t reckon it matters. This is how much powder you think you’d need to make a blast this big, is it?”

“Yes, sir,” Johannes said, standing at such strict attention he was vibrating. “Judging by the radius at which the blast cracked the flagstones, and the distance—”

“Yes, yes. Now, how big a pile would that much powder make?”

Johannes’ eyes crossed as he calculated. “If you just dumped it? It’d be roughly a cone. We can reverse the volume formula—”

“You’re not getting it. Lord knows I’m not surprised. Colonel, how big was the royal box?”

“Maybe ten by ten,” Marcus said.

“And how much space under it?”

“Not much. Less than a foot.”

The Preacher looked at Johannes. “Could you fit that much black powder in there?”

The boy blinked. “Er . . . no, sir. Not even close. But I’m sure my calculations weren’t that far off—”

“What it means,” the Preacher said, “is that we’re not dealing with ordinary black powder. Which you ought to have known from the start, because without a complicated fuse you can’t get a whole pile of powder to go off at once. It’d get sprayed around, you see?” At Johannes’ expression, he sighed. “You don’t see. God help us all.”

“So what happened?” Marcus said. He was starting to feel sorry for Johannes. “Something exploded.”

“You ever hear of flash powder?” the Preacher said, turning away from his hapless student. “Stage magicians use little bits of it sometimes. It’s basically your standard powder but ground up much finer so it burns faster and hotter. Not much good for guns or muskets, ’cause you’ll bust the barrel wide-open. It works for blasting, though, if you can afford to waste it.”

“I’m not sure I follow,” Marcus said.

“Flash powder’s expensive. It’s dangerous to make—the finer you grind powder, the better the chance that something’ll accidentally touch off the lot, you know? And like I said, it’s not good for much. You can usually get the job done with black powder just fine.” The Preacher looked back at the crater. “Unless you need to stick a big bomb in a small space.”

“So that’s what they used here?”

“Has to be. Quite a bit of it, too.” The Preacher shook his head. “I wouldn’t have wanted to be anywhere near it. It’s God’s grace that Her Majesty wasn’t there.”

“I can agree with that,” Marcus muttered. “Okay. Flash powder. Do you have any idea where that might come from?”

“Somewhere close by is the best I can tell you. It doesn’t travel well. Even a little damp will ruin it.”