ACROSS AFRICA BY AIR AND RAIL distance, while the two others did not succeed in getting across the desert wastes of the Sudan.

In the airplane of our imagination, let us take the trip they made. We may be sure of excitement, for even under favourable conditions we are starting out on one of the most dangerous air journeys known to the world. But let us first look at a map and pick out our route. It is a jagged line, extending from north to south, the length of the continent. It is marked with dots and triangles, each showing a place where we may land. As we look at the map it seems quite simple and easy, but actual experi¬ ence proves its great difficulties.

We shall leave Cairo at dawn and follow the Nile to Khartum. This is a flight of one thousand miles, but landing places have been prepared along the entire route at intervals of two hundred miles. We shall stop at one of these long before noon and spend several hours to avoid the heat of the day, when gusts of hot air, rising from the sun-baked desert, make it dangerous to fly at low altitudes. At the start of our flight we shall rise a mile or more to avoid these treacherous currents, which frequently take the form of “air spouts,” often visible on account of the dust and sand they have sucked up with them. Such cur¬ rents have force enough to toss our plane about like a leaf in the wind. With these great gusts of hot air spouting upward are cold currents rushing downward. These are even more dangerous, as they are always invisible. Con¬ sequently, we shall fly high, to avoid a “bumpy” passage, as our pilot calls it, and in landing must be careful lest we get caught in an air pocket.

From Khartum we start on the second, longest, and most dangerous leg of the journey. This covers a distance 161