“Only three?”

“It could have been one.”

“Impossible. One could not be in all three places at once.”

Bell said, “He wouldn’t have to be. The yacht and the steamboat both burned coal in sizable furnaces. A knowledgeable saboteur could have hidden dynamite and detonators fashioned to look like large chunks of coal in their bunkers.”

“But what would persuade the fireman—who was bound to die in the explosion—to shovel it into the furnace at just the right moment?”

Isaac Bell said, “I went aboard two of the steamboats that were clearing the channel. I took a good look at their boilers and I talked to their firemen.”

Joseph Van Dorn sat back in his chair and smiled. “Did you? What did you learn?”

“The coal is shifted in wheelbarrows from bunker to bunker, closer and closer to the furnace, in a logical manner. And the steamboats burn it at a consistent rate, depending on the speed they’re making and the current.”

“To calculate the timing, your provocateur must know all about steamboats, perhaps been employed on them.”

“No, sir. I figured it out, and I’m only a detective.”

Van Dorn looked out his window, cogitated in silence, then mused, “He sounds like quite an operator . . . Quite an operator . . . Provided he exists . . . But ‘fashioning’ dynamite and detonators to look like coal could be rather more difficult than you suggest.”

“Wally Kisley reckons that the runaway mine train was sabotaged with a so-called hollow or shaped charge. May I ask are you aware—”

“I know what a shaped charge is, thank you. Though, admittedly, the average farmer dynamiting stumps does not.”

“Nor the average coal miner dynamiting the seam,” said Bell.

“You are postulating a fellow with an extraordinary skill with explosives. I know what a shaped charge is, but I would likely blow my head off trying to fashion one. Particularly disguised as coal that would fool an experienced fireman. Extraordinary knowledge.”

“I’ve got Wish Clarke tracking down Laurence Rosania.”

“Rosania?” Van Dorn stroked his red whiskers. “Morally, I would put nothing past Rosania of course. But why would a successful safecracker with his refined tastes stoop to blowing up coal mines and steamboats? It wouldn’t be worth his trouble or the risk. He’s made a splendid career of not getting caught. Yet.”

“I’m betting that Rosania can point us toward other experts in what must be a small field of inquiry. And I’ve asked Grady Forrer to research who among the military are experimenting with hollow charges, other than the fellows at the Torpedo Station.”

Van Dorn asked, “What’s your next move?” and Isaac Bell realized with a swell of pride that the Boss was treating him more like a fellow detective than a new man on the job.

“My next move is to find out who bought a controlling interest in Black Jack Gleason’s coal mines and coking plants within a week of his death.”