The Wall disappeared behind a low step-mesa for a hundred meters and then curved down almost to the Tongue, and Carson’s pony apparently decided he’d gone far enough and stopped, swaying.

“Uh-oh,” I said.

“What is it?” Ev said, dragging his eyes away from the Wall.

“Rest stop. Remember how I told you they’re not dangerous?” I said, watching Carson, who’d gotten down off his pony and was standing clear. “Well, that’s if they don’t fall over with your legs under ’em. Think you can get down off him faster than you got on?”

“Yes,” Ev said, jumping down and away like he expected Speedy to explode.

I tightened the straps on the computer, dismounted, and stepped back. Up ahead, Carson’s pony had stopped swaying, and Carson had gone back up to it and was trying to untie the food packs.

Ev and I walked up and watched him struggle with the line. The pony dumped a pile practically on Carson’s foot and started swaying again.

“Tim-berr,” I said, and Carson jumped back. The pony took a couple of tottering steps forward and fell over, its legs out stiff at its side.

The pack was half under it, and Carson started yanking it out from under the motionless carcass. Bult unfolded himself and stepped decorously off his pony holding his umbrella, and the rest of the ponies went over like dominoes.

Ev went over to Carson and stood looking down on him. “Don’t make any sudden movements,” he said.

Carson stomped past me. “What are you laughing at?” he said.

We had lunch and incurred a few fines, but I didn’t get a chance to talk to Carson alone. Bult stuck like glue to us, talking into his log, and Ev kept asking questions about the Wall.

“So they make the chambers one at a time,” he said, looking across at it. We were on the wrong side of the Wall here, so all you could see were the back walls of the chambers, looking like they’d been plastered and painted a whitish-pink. “How do they build them?”