Dale crouched down next to the puddle and looked at it for a long time. The asphalt was still warm from the morning. Sally stood behind him. "It dries from the outside," Dale said. "That's the rule. The outside goes first. Then it works inward. Like a clock." Sally looked at the puddle. "The middle is always last," Dale said. "The middle is protected." He stood up. "That's just how puddles work," he said.

They watched it for a while. The middle dried first. Dale crouched back down and looked at it from a different angle. "This one's going the other way," he said. "That happens with certain puddles." "Which puddles," Sally said. "Shaded ones," Dale said. The puddle was in full sun. "Well," Dale said. "Shaded ones and sunny ones with a particular kind of asphalt." Sally looked at the asphalt. "What kind," she said. Dale looked at the asphalt for a moment. "Smooth asphalt," he said. "You can tell by the color." Sally looked at the color. "What color is it supposed to be," she said. "This color," Dale said. "Basically."

The puddle was almost gone now. It had dried from the middle outward, leaving a thin dark ring at the edge. Dale looked at the ring. "There it is," he said. Sally looked at the ring. "The outside's still wet," she said. "That's the shadow ring," Dale said. "The shadow ring always stays a little longer. Because of the angle of the sun." Sally looked up at the sun. It was directly overhead. "There's always an angle," Dale said. "Even when it doesn't look like it."

The last of the shadow ring dried up. Dale stood. He took a step back without meaning to and his heel came down in a small wet patch he hadn't seen behind him. He looked down at it. "Secondary ring," he said. "Good puddle," he said. He walked away. Sally looked at where the puddle had been. Then she looked at the wet heel print Dale had left walking away from it. Then she followed him.

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