In the last chapter we were reading about Egypt, and we said that on
the West of Egypt lay the Great Desert. Now a desert is a place where
for some reason no food will grow. In some deserts the soil is too
bad; in some the ground is covered with salt; in others, like the
Sahara, there are no rivers. In some places in the Sahara there is
water coming up through a crack in the rocks. This water is called a
"spring," and wherever one is found, trees and grass and food will
grow. Such a place is called an "oasis." In the big oases there are
villages and towns. But the sun is so hot that before the water from
the spring has flowed very far it is dried up, and beyond that nothing
will grow. So when we think of the Sahara we have to try and picture
to ourselves a very big country, full of hills and valleys, but with
no rivers or lakes. It is a journey of many months to cross the
Sahara, and day after day there is nothing to see but sand--sand, not
flat, but in ridges of hills like great waves of the sea. When people
are travelling across this desert, they get very tired of looking at
nothing but sand all day. Then, at last, as the sun sets, they reach
an oasis where there is water and bananas and date-trees, and perhaps
houses and people. Sometimes great winds blow in the desert and bring
a sandstorm. Then the sand beats hard against everything. If
travellers meet a sandstorm, they have to throw themselves face
downwards on the ground to keep the sand out of their eyes and mouth.
Very often people who live in the desert have bad eyes, and many are
blind because of the sandstorms.

2. How the Desert Came

Long, long ago, the Sahara was not quite so dry as it is now. There
were rivers then, which have dried up since. When there was water,
food would grow, and people could keep sheep and cattle. In those