432 



DELTA OF THE NILE. 



[Ch. XVIii. 



of the waves ; so that not only are fresh accessions of land 

 checked, but ancient parts of the delta are carried away. 

 By this' canse Canopns and some other towns have been 

 overwhelmed. The marine cnrrent alluded to is caused by 

 the prevalence for nine months of the year of winds from the 

 north-west, but they turn in the opposite direction when- 

 ever, during the remaining months, a wind sets in from the 

 east.' Another reason, however, for the slow advance of the 

 delta for the last two or three thousand years, is the slow 



made 



sequel. 



Nile for the last 1,500 miles 



by a single tributary, great or small ; a geographical pecu- 

 liarity exhibited by no other river in the world. In Nubia, 



thunderstorms 



are 



sometimes formed, some 



them 



tween the first and second cataracts, which wash gravel, 



The winds also blow clouds 



Nile 



of sand into it from the desert where the valley is narrow 



above the first cataract. . 



In passing through so many degrees of latitude exposed 

 to a hot sun and to arid winds blowing from the surround- 

 ing deserts, the river loses much of its water by evapora- 

 tion, especially where it is spread out over the plains during 

 the season of inundation, which lasts about four^ months. 

 The sediment annually left behind on the plain consists of an 

 extremely thin film of matter, most of the mud 

 thrown down on the banks, which here, as in all other great 

 rivers, are higher than the flat region between them and 

 the heights bounding the valley on each side, so that during 

 the flood season the banks are 



emer 



above 



the waters, and forming two long narrow strips of land. 

 The base of the delta is more than 200 miles in length, i 

 we include in it all that part of the coast which intervenes 

 between the ancient extreme eastern and western arms ; va 

 these are blocked up at present, and that part of the coast-toe 

 about 90 miles in length which extends from the Eosetta , to 

 the Damietta branches is the only portion now usually calle 

 the Delta. The diameter of this low tract from south o 







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( 



an 



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