VALLEYS AND GREAT LEVELS OF THE EARTH. 229 



and the measure of the work that remains for you to do ; he comes when you strike your 

 tent in the early morning, and then, for the first hour of the clay, as you move forward on 

 your camel, he stands at your near side, and makes you know that the whole day's toil is 

 before you : then for a while, and for a long while, you see him no more for you are 

 veiled and shrouded, and dare not look upon the greatness of his glory ; but you know 

 Avhere he strikes over head by the touch of his flaming sword. No words are spoken ; but 

 your Arabs moan, your camels sigh, your skin glows, your shoulders ache ; and for sights 

 you see the pattern and web of the silk that veils your eyes, and the glare of the outer 

 light; but conquering Time marches on, and by and by the descending sun has compassed 

 the heaven, and now softly touches your right arm, and throws your lank shadow over 

 the sand, right along on the way to Persia." Beyond the Euphrates to the Tigris, with 

 the exception of slips along the two rivers, the country is a desert of burning sands and 

 sterile gypsum, thickly studded with saline and sulphurous pools ; and farther eastward 

 the zone of deserts may be traced through Persia, Grand Tartary, and the great central 

 plateau of Asia, extending thus in an almost continuous band of varying breadth from 

 the Atlantic Ocean to the wall of China. Analogous phenomena to those of the 

 Sahara the mirage and encroaching sands are displayed through the greater part 

 of this zone, which proceeds in a circle, the arc of which is directed towards the south, 

 through the whole of the ancient world. Especially in some regions of south-western 

 Asia has the dry element sensibly advanced. Once rich and-blooming territories, celebrated 

 by the Persian poets as paradisiacal, the theatre of heroic deeds, the seat of political power 

 and intellectual culture, the site of cities which in size and splendour were second to 

 none in Asia, have been visited by the moveable sand, leaving but few evidences of 

 former grandeur and fertility apparent. At Samarcand and Bokhara, celebrated 

 sovereign cities, from which, in the middle ages, bold and chivalrous princes overspread 

 the East with their flying squadrons, the sands have with difficulty been kept at bay. 

 The river Sihun has been compelled to alter its course, and the mighty Oxus of the 

 ancients, according to historical evidence, has lost its Caspian arm in a struggle with 

 the desert. Setting aside the fertile oases, Humboldt supposes the area of the sandy 

 deserts, leaving out those of central Asia, to be 300,000 square leagues. Those of the 

 Tartarian table-land cannot be less than 100,000 more, and adding 100,000 for similar 

 tracts in Midland and Southern Africa, with some other districts, we have a grand total 

 of half a million of square leagues of such surface in the Old World ; a space equal to the 

 whole extent of Europe. 



The deserts to which the preceding notices refer, are for the most part hot sandy 

 districts, or experience great alternations of heat and cold. Independently of these, 

 there are cold tracts of lowland, chiefly found in the northern regions of Asia. From 

 the declivities of the Ural on the west, to the coast of Kamtschatka on the east, and from 

 the foot of the Altaian Mountains on the south, to the icy margin of the Arctic Ocean 

 on the north, there is a country almost as large as Europe, a melancholy desert, in which, 

 in latitude 67, the growth of trees ceases altogether ; and a little higher up the soil is 

 frozen the whole year through, some few inches of the surface alone being subject to an 

 annual thaw : but at a short distance from the surface, throughout Siberia, a bottom of 

 perpetually frost-bound soil is met with. Gmelin the elder, in his travels, states that 

 shortly after the foundation of the town of Yakutsk, in lat. 62^ north, at the end of the 

 seventeenth century, the soil of that place was found to be frozen at a depth of ninety-one 

 feet, and that the people were compelled to give up the design of sinking a well, a state 

 ment corroborated in our days by the travels of Erman and Humboldt. Until very lately 

 nothing was known respecting the thickness of the frozen surface ; but within these few 

 years a merchant of the name of Schargin, having attempted to sink a well at Yakutsk, was 



