ould, if barometers commonly grew in the desert, where, however, in the
present condition of science, they are rarely found. It is this dryness
of the air, and this alone, that makes a desert; all the rest, like the
camels, the sphinx, the skeleton, and the pyramid, is only thrown in to
complete the picture.

Now the first question that occurs to the inquiring mind--which is but a
graceful periphrasis for the present writer--when it comes to examine in
detail the peculiarities of deserts is just this: Why are there places
on the earth's surface on which rain never falls? What makes it so
uncommonly dry in Sahara when it's so unpleasantly wet and so
unnecessarily foggy in this realm of England? And the obvious answer is,
of course, that deserts exist only in those parts of the world where the
run of mountain ranges, prevalent winds, and ocean currents conspire to
render the average rainfall as small as possible. But, strangely enough,
there is a large irregular belt of the great eastern continent where
these peculiar conditions occur in an almost unbroken line for thousands
of miles together, from the west coast of Africa to the borders of
China: and it is in this belt that all the best known deserts of the
world are actually situated. In one place it is the Atlas and the Kong
mountains (now don't pretend, as David Copperfield's aunt would have
said, you don't know the Kong mountains); at another place it is the
Arabian coast range, Lebanon, and the Beluchi hills; at a third, it is
the Himalayas and the Chinese heights that intercept and precipitate all
the moisture from the clouds. But, from whatever variety of local causes
it may arise, the fact still remains the same, that all the great
deserts run in this long, almost unbroken series, beginning with the
greater and the smaller Sahara, continuing in the Libyan and Egyptian
desert, spreading on through the larger part of Arabia, reappearing to
the north as the Syrian desert, and to the east as the desert of
Rajputana (the Great Indian Desert of the Anglo-Indian mind), while
further east again the long line terminates in the desert of Gobi on the
Chinese frontier.

In other parts of the world, deserts are less frequent. The peculiar
combination of circumstances which goes to produce them does not
elsewhere occur over any vast area, on so large a scale. Still, there is
one region in western America where the necessary conditions are found
to perfection. The high snow-cl