CHAP. XI. DYKES. 107 



probably owing, in some degree, to the numerous 

 channels in that direction, and to the effect of the 

 currents wliich pass over it as the water covers the 

 land : though they are not sufficient to account 

 for the great difference between the height of the 

 bank and the land near the edge of the desert, 

 which is often 12 or 15 feet, as may be seen from 

 the respective heights of the dykes at those two 

 points. 



These elevated roads, the sole mode of com- 

 munication by land from one village to another, 

 during the inundation, commence on a level with 

 the bank of the river, and, as they extend to 

 the interior, become so much higher than the 

 fields, that room is afforded for the construction of 

 arches to enable the water to pass through them ; 

 though, generally speaking, bridges are only built 

 on those parts, where ancient or modern canals 

 have lowered the levels sufficiently to admit of 

 them. The general appearance of the dykes may 

 be illustrated by a section*, in which A is the 

 surface of the Nile during the inundation ; B, the 

 level of the low Nile ; C, the bank ; D D, the raised 

 dyke ; E, the beds of canals over which bridges 

 are built in the dyke; F, the Hdger, or slope of the 

 desert, extending from the junction of the irrigated 

 land at H to the limestone mountains G. 



This section is given as if the dyke were in one 

 straight line East or West from the river ; but they 

 follow a tortuous course, visiting the various towns 

 on their way, and serving as roads, as well as an 



* Plate 18. No. 1. 



