re in smaller units.

The Ahaggar covers roughly an area the size of Pennsylvania, New York,
Virginia and Maryland combined, and supports a population of possibly
twelve thousand, which includes about forty-five hundred Tuareg, four
thousand Negro serf-slaves, and some thirty-five hundred scorned
sedentary Haratin workers. The balance of the population consists of a
handful of Enaden smiths and a small number of Arab shopkeepers in the
largest of the sedentary centers. Europeans and other whites are all
but unknown.

It is the end of the world.

Contrary to Hollywood-inspired belief, the Sahara does not consist
principally of sand dunes, although these, too, are present, and all
but impassable even to camels. Traffic, through the millennia, has
held to the endless stretches of gravelly plains and the rock ribbed
plateaus which cover most of the desert. The great sandy wastes or
ergs cover roughly a fifth of the entire Sahara, and possibly two
thirds of this area consists of the rolling sandy plains dotted
occasionally with dunes. The remaining third, or about one fifteenth
of the total Sahara, is characterized by the dune formations of
popular imagination.

It was through this latter area that Homer Crawford, now with but one
hover-lorry, and accompanied by Isobel Cunningham and Clifford
Jackson, was heading.

For although the spectacular major dune formations of the Great Erg
have defied wheeled vehicles since the era of the Carthaginian
chariots, and even the desert born camel limits his daily travel in
them to but a few miles, the modern hovercraft, atop its air cushion
jets, finds them of only passing difficulty to traverse. And the
hovercraft leaves no trail.

Cliff Jackson scowled out at the identical scenery. Identical for more
than two hundred miles. For twice that distance, they had seen no
other life. No animal, no bird, not a sprig of cactus. This was the
Great Erg.

He muttered, "This country is so dry even the morning dew is
dehydrated."

Isobel laughed--she, too, had never experienced this country before.
"Why, Cliff, you made a funny!"

They were sitting three across in the front seat, with Homer Crawford
at the wheel, and now all three were dressed in the costume of the Kel
Rela tribe of the Ahaggar Tuareg confederation. In the back of the
lorry were the jerry-cans of water and the supplies that meant the
difference between life and mummification from sun and heat.

Cliff turned suddenly t