"What are you doing?" Morrison asked.
"I'm making depth-photographs of the terrain," the robot said. "It's rather difficult in this light. Couldn't you wait till morning?"
"No!"
"Well, I'll just have to cope," the robot said.
It moved and stood, moved and stood, each subterranean exposure taking longer than the last as the twilight deepened. If it had had pores, it would have sweated.
"There," said the robot at last, "that takes care of it. Do you have a sample for me to take back?"
"Here it is," Morrison said, hefting the slab of goldenstone and handing it to the surveyor. "Is that all?"
"Absolutely all," the robot said. "Except, of course, that you haven't given me the Deed of Search."