“There is atmosphere here,” he observed slowly, “but it is exceedingly thin.”

“It is not half as thin as these air helmets promise to become,” Billy snorted, “and I think I can explain it. The astronomers on the earth cannot see deep into these craters. They see only the tops of the mountains, and the atmosphere has done the same as it does on the earth—sought the lower levels, being pressed down from above and gathering density in the holes and caves.”

“That being the case right here we separate from Toplinsky,” Epworth decided quickly. “If we wait he will put a watch over the ship, and cut off our escape.”

“You say that Toplinsky has been shooting liquid air, oxygen, nitrogen and hydrogen up here?”

Joan put the question to Michael as if she had just heard this, and Epworth looked at her in surprise.

“Of course,” Epworth answered, taking the words out of Michael’s mouth. “That has been gone over half a dozen times.”

“True, but a new idea has just struck me. Perhaps the liquid air and all the other ingredients that make air, which Toplinsky shot up here, made good breathing air when the explosions occurred and that enough have been unloaded from the earth to create a small air circle at this point.”

“Such atmosphere would be held down at this point by the pressure from above,” Epworth agreed, “and remain in natural form.”

“If my theory proves true,” Joan continued, “we can breathe only when we are near the lake.”

“Be that as it may, we will go out and see how we get along but be sure to hold on to your air helmets.”