122 NATURAL HISTORY OF 



cause of the destruction of the caravan trade, already on the 

 decline during the Roman empire, and show that the efforts 

 of Russia to revive it are unavailing, because, the course of the 

 Oxus being changed, trade no longer reaches the Caspian by 

 boats; and, moreover, water becoming annually more scarce, 

 the nomad hordes of the desert, gradually deprived of cultiva- 

 tion by the inroads of the sea-sand, and driven eastward by the 

 want of that necessary element, are necessitated to live by 

 rapine where the earth grants no subsistence.* 



Rivers like the Jaxartes, now denominated the Syrderiah, or 

 Syhoun, and the Oxus, since called Jeyhoun and Amou, 

 which, according to the ancients, originally flowed more 

 directly westward to the Caspian, are now turned into the 

 Aral, — a result which changes in the plane of declivity alone 

 could produce, although the fact has been repeatedly ascribed 

 to the labors of a poor, idle, and scanty population, destitute of 

 mechanical skill, and almost of property in the soil. The Jax- 

 artes now reaches Lake Aral through a sedgy bed, filling the 

 north-eastern angle with clusters of islands, successively pro- 

 duced by the deposits bearing the same aquatic plants. The 

 Tanghi-Deriah, said, anciently, to have constituted the Deltic 

 branch of the Jaxartes, which discharged its waters into the 

 Caspian, is reported to have been turned off by the Khokani- 

 ans, who, dreading the Khiva robbers might plant colonies of 

 their own people along the stream, raised a bank to cut off the 

 current. Although great rivers are not to be thus turned from 

 their natural course, the dry bed certainly exists. It is now 

 overgrown with Anabasis ammodendronA 



* See Report to the Acad, des Sciences, Paris, by M. Hommaire Dehel, 

 on the levels of the Caspian and Aral, and on the decrease of the Oxus 

 and Volga. April, 1843. 



t We doubt this being the same as the Janderiah, which forsook its bed 

 so late as 1816. Report of a Memoir by M. A. De KanikofT, to the Geo- 

 graphical Society of London, November, 1844. It is reported by Arab an 

 authors that both rivers remained dry for seven years, about 460, and the 



