"Yeah," said Syme, and opened the door. The air in the car whooshed into the near-vacuum outside, and he and Tate stepped out.
The Martian leader looked at them enigmatically, then turned and started off. The other natives closed in on them, and they all bounded along under the weak gravity.
They bounded along for what Syme figured as a good kilometer and a half, and they then reached a branch in the gully and turned down it, going lower all the time. Under the light of their helmet lamps, they could see the walls of the gully—a tunnel, now—getting darker and more solid. Finally, when Syme estimated they were about nine kilometers down, there was even a suggestion of moisture.
The tunnel debouched at last into a large cavern. There was a phosphorescent gleam from fungus along the walls, but Syme couldn't decide how far away the far wall was. He noticed something else, though.
"There's air here," he said to Tate. "I can see dust motes in it." He switched his helmet microphone from radio over to the audio membrane on the outside of the helmet. "Kalis methra," he began haltingly, "seltin guna getal."
"Yes, there is air here," said the Martian leader, startlingly. "Not enough for your use, however, so do not open your helmets."
Syme swore amazedly.
"I thought you said they didn't speak Terrestrial," Tate said. Syme ignored him.
"We had our reasons for not doing so," the Martian said.
"But how—?"