24 COTTON 



and the elaborate system of irrigation. The rainfall 

 of Egypt is exceedingly small, amounting in average 

 years to only 1-5 inches at Cairo and 7-8 inches at 

 Alexandria. During the whole period of vegetative 

 growth of the cotton plant, little or no rain falls, but 

 the land is fortunately provided with a sufficiency of 

 water by the rise of the Nile and the distribution of 

 its water by means of numerous canals. 



The mean annual temperature in the Delta varies 

 from 69*iF. at Alexandria to 70- 3 F. at Cairo. 

 Further up the river, at Assouan, it reaches 80 F. 

 The extremes of temperature observed at Alexandria 

 are 45* i F. as a minimum and 99* 3 F. as a maximum. 

 At Cairo, as would be expected from its greater 

 distance from the sea, the range is wider, the extremes 

 being 36*5 and IO9'2F. 



The arable soils of Egypt consist almost entirely 

 of alluvial deposits, but, since the conditions pre- 

 vailing at their formation were not always the same, 

 the soil does not everywhere present the same physical 

 properties and chemical composition, and the nature 

 of the deposit varies with the depth. 



In Upper Egypt, the ancient bed of the river con- 

 stitutes what is known as the Nile Valley. The river 

 here, during the annual flood, is diverted, by means 

 of flood-level canals, to fill large basins, where the 

 water deposits the alluvium and is then either dis- 

 charged into a lower-level basin and returned to the 

 Nile or allowed to sink entirely into the soil. By 

 repeated deposits of alluvium the arable land of the 

 Nile Valley has been reclaimed from the desert. 



The Delta, on the other hand, has been won from 

 the sea by the rapid deposition caused by the mingling 

 of the river with the salt water. A difference has 

 consequently arisen in the nature of the soil of the 

 two regions. In the Nile Valley, the deposition of 

 the alluvium has been effected by gravitation alone, 

 and the soil is therefore not so rich in clay as is that 

 of the Delta, where the salt of the sea has caused a 

 more rapid precipitation of the argillaceous matter 

 and has also made the land more saline. 



The typical soil of the Delta is a heavy, black clay 



