"Sorry!" Linh said brightly. "So clumsy!"
"No more today," Wendell said quietly, a minute later, leaning over the gap between the booths with his hat held down on his head. "Wind like this, nobody floats. Not Valentin, not your grandma. Breathe with the wind means know when to sit down."
But June didn't sit down.
She stood behind the counter the rest of the afternoon squeezing lemons and thinking, and that night after the storm had blown through and the concourse was steaming under the lights, she got Wendell's toolbox and the black notebook and sat cross-legged on the sawdust under the counter with a flashlight in her teeth.
The problem, she figured, was that the line was too long. Seven feet, from Wendell's pole to her hand. A seven-foot line in the wind was a guitar string. And the cup itself was the problem too. The waxed paper was so light it would catch any breath of air, like a sail.
You couldn't make the wind stop. You could make the cup heavier, but then the thread would break. You could make the thread thicker, but then people would see it.
Or.
She was thinking of her father, actually, of the time he'd shown her how the governor worked on the old John Deere, two little weights on arms that spun out wider the faster the engine ran, and how that kept it steady. Steady wasn't about strength. It was about where you put the weight.
At one in the morning she woke up Linh, who was asleep on the sugar sacks, and showed her. She'd taken one of the trick cups and pressed a single copper penny, flat, into the very bottom, under a disk cut from another cup so nobody would see it. Then she'd punched the two pinholes a little higher, right up against the rim, almost at the lip.
"It hangs lower now," June said, holding it up on a short length of thread. She blew on it, hard. The cup swung, and settled, and swung less, and settled. "See? The weight's further below the line. It's like a pendulum. It wants to hang straight. It doesn't spin anymore. And the penny's only two and a half grams. The thread can take it."
Linh blew on it too. Then she took the cup and blew on it from underneath, and from the side.
"Your center of mass is lower than your pivot," she said, impressed. "That's real stability."
"I don't know what any of that means," June said. "I just figured it out."