numerous situations involving large crowds. We can speak of the flow of information in a crowd much as we might speak of the flow of information in a pond. Suppose a lad throws a stone into the air. It lands at point A, and the dynamics of incompressible fluids dictate that the gravity waves spread out in a circular manner from the point of impact.
“Knowing as I do the equations that govern these dynamics, I could tell you when the first ripples from that stone would strike the shore. Now, here is where things get interesting. I could also solve the inverse problem. That is to say, if I came along some time after the lad threw his stone and merely observed the wavelets washing at my feet at some time, T, I could tell you very well where that stone hit the water even though I never saw it with my own eyes. I can make time move backward, if you will.”
He stepped aside and nodded at Lydia, who wrote an equation on the board. Alexander gave the numbers a cursory glance but couldn’t keep his eyes from the graceful movement of Lydia’s arm as she wrote, the studious concentration on her lovely features.
Warmth and pride filled Alexander’s chest. He loved watching her mind work, knowing the complexity of the wheels and gears turning behind her blue eyes. Knowing that every other man in the room must be astonished by her brilliance.
Lydia turned to face the audience again.
“Therefore, we assert, gentlemen,” she said, “that it is the same with the riot. A crowd is very much like a pond, a dense aggregation of particles that transmit information by colliding with one another.”
“And we can solve the inverse problem as well,” Dr. Sigley continued, pointing at the equation. “Though I was not there, I can state unequivocally that if Lord Northwood was indeed where you say he was at the time stipulated—and there are numerous credible witnesses who can corroborate this very thing, as I’m certain the inspectors can verify—then the laws of motion preclude his having initiated the disturbance that propagated through the medium at the nominal rate of fifty feet per minute—”
“What the devil is he on about, Miss Kellaway?” Hadley interrupted.
“My lord,” Lydia said. “The very basic conclusion of Dr. Sigley’s calculations is that Lord Northwood was not the slightest bit at fault for causing the riot. He was here.” She smacked her pointer against the gallery on the map. “And the flow-density calculations, which you are all welcome to observe more closely, indicate the riot started here.”
Another strike at the entrance of the hall emphasized her point. The audience was silent for a moment before a rumble began—questions, a couple of shouts, people standing to peer at the evidence.
“I’ll be damned,” Sebastian muttered.
Hadley stared at the map, then down at the papers Lord Perry had given him. The police inspectors approached the council table, lowering their heads to speak with the members.
A great deal of discussion and gesturing ensued, with Sir George Cooke approaching the mathematicians to point out items on the papers. Another council member began a discussion with Lord Perry, while the police inspectors scratched their heads and a couple of the other council members merely appeared bewildered. Union representatives from the crowd approached the dais to confer with the mathematicians and council members.
Lydia stood to one side, speaking with several men, her expression serious and confident. Alexander waited until she was alone for a moment before he stepped in front of her.
She lifted her gaze, her eyelashes like dark feathers against her white skin. Desire and… more simmered in her expression. He wanted to touch her. He wanted to kiss her. His fingers curled into his palms as he fought the urge.
“Why?” he asked.
She blinked, her gaze slipping to his throat. Her shoulders lifted in a shrug, though the casual gesture contradicted the multitude of emotions in her eyes.
“The calculations work,” she said.
“That’s not an answer.”
“It’s the only one I can give you.”
“Beg your pardon, Miss Kellaway?” Lord Perry touched Lydia’s arm to garner her attention and cast a faintly hostile glare at Alexander. “Your opinion on the ratio equation, if you please?”
Alexander stepped back and returned to his seat, not taking his eyes off Lydia as she moved to the board and commenced a discussion with two other men.
After a good half hour of buzzing and commotion, Hadley waved his arms about again. “Order! Everyone be seated, please. We’ve come to a