in drilling this well, maybe partly as a whim, and partly to be assured of water for his people in the height of an over-long summer. Since visiting Melen I have travelled far in the Sahara, and know many wells in like God-forsaken places, each of which suggests that it belongs to a bygone age when greater fertility made it possible for the nomads to camp where they willed, which—if we take such wells as significant—was sometimes in localities that they cannot camp in now. [Illustration: TYPICAL TASSILI] Wherefore, in many strange ways, it comes back to one, always, that the Sahara is a decadent land. And that is a steadfast impression, that the traveller is always catching, even when least expected. And, now, to broadly picture the aspect of the country, the Sahara is not, of course, as is often popularly believed, simply a vast track of desert sand. The “floor” of its vast area is made up, principally, of four types of country, which I describe as follows, along with the names by which they are known to the nomads: (1) “_Tenere_” (Tamascheq[6]) =Absolute sandy desert. “_Arummila_” (Arabic) (2) “_Adjadi_” or “_Igidi_” =Regions of permanent sand-dunes, (Tamascheq) sometimes barren, sometimes with scattered vegetation. “_Erg_” (Arabic) (3) “_Tanezrouft_” =Regions where the sand is hard (Tamascheq) and interspersed with plains of pebbles. Sometimes great gravel “_Reg_” (Arabic) plains as barren as sand desert and hence often called _Black Desert_ by the Tuaregs. (4) “_Tassili_” (Tamascheq) =Regions of chiefly horizontal, rough, rocky, much crevassed “_Elkideà_” (Arabic) ground, often of shelf rock, where decomposition is very rapid and outcrops much cracked and broken apart. The ground surface, or plateau surface, is usually as barren as sand desert, but in deep ravines in such country there is often a sparse growth of vegetation. As a whole all those regions are practically horizontal, and, except in the north, are on a level well above the sea. Between longitude 5° and 10°, from south to north, the altitudes of the Saharan plains, above sea-level, are approximately: