* * * * *

So now Jan gripped his clay pipe between his teeth and piloted the
groundcar into the teeth of the Twilight Gale.

Den Hoorn was a comparatively flat desert sweep that ran along the
western side of the Oost Mountains, just over the mountain from
Oostpoort. It was a thin fault area of a planet whose crust was
peculiarly subject to earthquakes, particularly at the beginning and end
of each long day when temperatures of the surface rocks changed. On the
other side of it lay Rathole, a little settlement that eked a precarious
living from the Venerian vegetation. Jan never had seen it.

He had little difficulty driving up and over the mountain, for the Dutch
settlers had carved a rough road through the ravines. But even the
2-1/2-meter wheels of the groundcar had trouble amid the tumbled rocks
of Den Hoorn. The wind hit the car in full strength here and, though the
body of the groundcar was suspended from the axles, there was constant
danger of its being flipped over by a gust if not handled just right.

The three earthshocks that had shaken Den Hoorn since he had been
driving made his task no easier, but he was obviously lucky, at that.
Often he had to detour far from his course to skirt long, deep cracks in
the surface, or steep breaks where the crust had been raised or dropped
several meters by past quakes.

The groundcar zig-zagged slowly westward. The tattered violet-and-indigo
clouds boiled low above it, but the wind was as dry as the breath of an
oven. Despite the heavy cloud cover, the afternoon was as bright as an
Earth-day. The thermometer showed the outside temperature to have
dropped to 40 degrees Centigrade in the west wind, and it was still
going down.

Jan reached the edge of a crack that made further progress seem
impossible. A hundred meters wide, of unknown depth, it stretched out of
sight in both directions. For the first time he entertained serious
doubts that Den Hoorn could be crossed by land.

After a moment's hesitation, he swung the groundcar northward and raced
along the edge of the chasm as fast as the car would negotiate the
terrain. He looked anxiously at his watch. Nearly three hours had passed
since he left Oostpoort. He had seven hours to go and he was still at
least 16 kilometers from Rathole. His pipe was out, but he could not
take his hands from the wheel to refill it.

He had driven at least eight kilometers before he realized that the
crack w