lowed them to miss both asteroid belts.

They started moving toward the planet Terra, reaching their objective in
less than three hours.

The globe beneath them was lit brightly, for they had approached it from
the daylight side. Below them, they could see wide, green plains and
gently rolling mountains, and in a great cleft in one of the mountain
ranges was a shimmering lake of clearest blue.

The air of the planet screamed about them as they dropped down, and the
roar in the loudspeaker grew to a mighty cataract of sound. Morey turned
down the volume.

The sparkling little lake passed beneath them as they shot on,
seventy-five miles above the surface of the planet. When they had first
entered the atmosphere, they had the impression of looking down on a
vast, inverted bowl whose edge rested on a vast, smooth table of deep
violet velvet. But as they dropped and the violet became bluer and
bluer, they experienced the strange optical illusion of "flopping" of
the scene. The bowl seemed to turn itself inside out, and they were
looking down at its inner surface.

They shot over a mountain range, and a vast plain spread out before
them. Here and there, in the far distance, they could see darker spots
caused by buckled geological strata.

Arcot swung the ship around, and they saw the vast horizon swing about
them as their sensation of "down" changed with the acceleration of the
turn. They felt nearly weightless, for they were lifting again in a high
arc.

Arcot was heading back toward the mountains they had passed over. He
dropped the ship again, and the foothills seemed to rise to meet them.

"I'm heading for that lake," Arcot explained. "It seems absolutely
deserted, and there are some things we want to do. I haven't had any
decent exercise for the past two weeks, except for straining under high
gravity. I want to do some swimming, and we need to distill some water
for drink; we need to refill the tanks in case of emergencies. If the
atmosphere contains oxygen, fine; if it doesn't, we can get it out of
the water by electrolysis.

"But I hope that air is good to breathe, because I've been wanting a
swim and a sun bath for a long time!"

XIII

The _Ancient Mariner_ hung high in the air, poised twenty-five miles
above the surface of the little lake. Wade, as chemist, tested the air
while the others readied the distillation and air condensation
apparatus. By the time they had finished, Wade was ready with