Then the railways came to the American West, just as they are coming to North Africa to-day, and the desert was awakened from its lethargy of centuries by the shriek of the locomotive. The first railroads to be constructed were designed primarily as highways between the Atlantic and the Pacific seaboards, with hardly a thought of revenue from the desert itself. But hard on the heels of the railway-builders followed the miners and the cattlemen, so that to-day the iron highway across the desert is bordered by prosperous cities and villages, by mines and oil-derricks and ranches and white farm-houses with green blinds, this one-time arid region, which the wiseheads of thirty years ago pronounced worthless, now yielding a wealth twice as much per capita as that of any other portion of the United States. What has already been accomplished in the American desert, French brains, French energy, and French machinery are fast accomplishing in the Sahara. Thanks to the recent invention, by a non-commissioned officer of France's African forces, of a six-wheeled motor-sledge driven by a light but powerful aeroplane engine, the problem of rapid communication in these desert regions, which have hitherto been impassable to any kind of animal or mechanical traction, has been solved. As the new vehicle has proved itself capable of maintaining a speed over sand dunes of twenty miles an hour, it promises to be of invaluable assistance to the French in their work of opening up the waste places. Not only have French expeditions explored and charted the whole of the unknown regions, but they have thoroughly investigated the commercial possibilities of the immense territories which have recently come under their control. These investigations have shown that the Sahara is very far from being the sandy plain, flat as a billiard-table, which the pictures and descriptions in our school geographies led us to believe, and which the reports of those superficial travellers who had only journeyed into the desert as far as Biskra, in Algeria, or Ghadames, in Tripolitania, confirmed, but is, on the contrary, of a remarkably varied surface, here rising into plateaus like those of Tibesti and Ahaggar, there crossed by chains of large and fertile oases, and again broken into mountain ranges, with peaks eight thousand feet high, greater than the Alleghanies and very nearly as great as the Sierra Nevadas.