io8 THE WORLDS LUMBER ROOM. 



Many of the river sands of Ceylon consist of fragments 

 of rubies, sapphires, and garnets, intermixed with others of 

 quartz and mica ; and the bed of the Manickganga in par- 

 ticular is composed to such a large extent of ruby sand that 

 it reminds one of the story of Sindbad - } but, as none of these 

 precious fragments is larger than a mustard seed, the sand 

 is valueless except for polishing and for sawing ivory. 



Among the great accumulations of sand existing at the 

 present day must be mentioned those of the desert of Gobi, 

 lying north of the Himalayas, concerning whose buried cities 

 and marvellous hidden treasures many tales are told. One 

 of these cities, named Pirna, is said by the Chinese to have 

 been suddenly overwhelmed in the sixth century; and an 

 interesting account exists of the flight from another, called 

 Katali or Kank, of a Mahometan priest, who for many suc- 

 cessive Fridays had warned his flock ot the calamity about 

 to fall upon the city. 



In this desolate region the wells are all protected by 

 huts, else they would soon be choked by the ever-shifting 

 sand, which stretches away in the distance like a great sea 

 marked by regular waves; which rise, one behind the other 

 in rows, to the height of ten, twenty, or even one hundred 

 feet, leaving the hard under-lying clay exposed to view be- 

 tween them. 



The advance of the sand takes place chiefly in the 

 spring, when the wind blows constantly from the north ; but 

 even then it is often so gradual that people will go on 

 occupying a tenement, whose court may be filled with sand 

 up to the verandah, from the breaking of the sand-dune 

 over the wall. 



