"We'll get to that," resumed the latter. "Meanwhile I'll stick to Tweel and his people. We spent the better part of three days with them, as you know. I can't give every detail, but I'll summarize the important facts and give our conclusions, which may not be worth an inflated franc. It's hard to judge this dried-up world by earthly standards.

"We took pictures of everything possible; I even tried to photograph that gigantic mural in the library, but unless Tweel's lamp was unusually rich in actinic rays, I don't suppose it'll show. And that's a pity, since it's undoubtedly the most interesting object we've found on Mars, at least from a human viewpoint.

"Tweel was a very courteous host. He took us to all the points of interest — even the new water-works."

Putz's eyes brightened at the word. "Vater-vorks?" he echoed. "For vot?"

"For the canal, naturally. They have to build up a head of water to drive it through; that's obvious." He looked at the captain. "You told me yourself that to drive water from the polar caps of Mars to the equator was equivalent to forcing it up a twenty-mile hill, because Mars is flattened at the poles and bulges at the equator just like the earth."

"That's true," agreed Harrison.

"Well," resumed Jarvis, "this city was one of the relay stations to boost the flow. Their power plant was the only one of the giant buildings that seemed to serve any useful purpose, and that was worth seeing. I wish you'd seen it, Karl; you'll have to make what you can from our pictures. It's a sun-power plant!"

Harrison and Putz stared. "Sun-power!" grunted the captain. "That's primitive!" And the engineer added an emphatic "Ja!" of agreement.

"Not as primitive as all that," corrected Jarvis. "The sunlight focused on a queer cylinder in the center of a big concave mirror, and they drew an electric current from it. The juice worked the pumps."