ithfully defend the caravan in case of attack by Bedouin Arabs. On the
other hand, should the garfla sheik forget the present to the sultan, or
neglect to hire guards, those same Tuaregs would be the first to attack
and loot the caravan.

The Bedouin Arab is the chief trial of the caravans. He is always a foe
to them; and although he ostensibly herds camels and horses, his real
occupation is robbery and pillage. For days nomadic Arabs will follow a
caravan, keeping always out of sight. Most likely a band of a dozen or
more mounted on swift horses will survey the caravan from a distance at
which they are not likely to be discovered. Then they make their way
ahead of it to some point where a dune or a gully will conceal them.
Then, just as the end of the caravan drags by, there is a sudden sortie
and a rattling musket fire. And before the guards can gather to the
defence half a dozen camels are cut out of the train, a driver or two is
shot down or pierced with assegais, and both the robbers and their loot
are beyond the reach of the guards.

But perhaps the greatest value of the desert is its effect upon the
climate of Europe. Hot winds blow from the Sahara in all directions; the
northerly winds, crossing the Mediterranean, are not only tempered
thereby, but the desert blasts tempered and filled with moisture finally
reach the southern slopes of Europe, where they convert the nutrition of
the soil into bountiful crops of corn, wine, and oil.

The conquest of the great African desert is already in sight, and the
railway will be its master. The Cape to Cairo line is no longer a vision
of the future; the ends of its two parts are rapidly shortening the
interval that separates them and they are almost in sight of each other.
When the lines that are projected from the Mediterranean coast shall
have traversed the stronghold of the Tuaregs to penetrate the wealth of
the Sudan and the Kongo, the Sahara will have become merely an incident.

CHAPTER XI

POLAR REGIONS--THE CONQUEST OF THE ARCTIC

Excepting the arctic and the antarctic regions, with their
fortifications of eternal ice and snow, intrepid explorers have made
known nearly every part of the world. There Giant Frost guards his
frozen secrets and defies man to wrest them from him. Many a hero has
perished in endeavoring to solve the Sphinx-like riddle of northern
lands and seas. Many a gallant ship has found its grave in northern
ice-clad waters. Yet there ha