COTTON IN EGYPT AND THE SUDAN. 17 



saturation. In Alexandria the humidity of the air is mostly 70 per 

 cent, and 80 per cent., and the maximum 97 per cent., and for 

 example, only one day in 1911, in April, had 35 per cent., one day 

 in January 40 per cent., and in the whole of the year only 35 days had 

 less than 60 per cent. In the south of Egypt the atmosphere is 

 remarkably dry, and on account of this dryness cotton in Upper 

 Egypt is, no doubt, unfavourably affected. Assuan shows on an 

 average throughout the year only 35 per cent. 



A consequence of the small rainfall and of the clearness of the 

 sky during the day is that in Egypt the cotton plants are exposed to 

 a great amount of sun, which is very favourable to their growth in 

 the early stages, but in Upper Egypt the plants seem to suffer some- 

 what from too much light. 



The fluctuation of the air-pressure is trifling. 



IRRIGATION AND LAND RECLAMATION. 



As has already been said, agriculture in Egypt depends upon 

 irrigation, entirely independent from the limited atmosphere precipita- 

 tion of rain, and this system has made it possible to grow in a 

 desert climate valuable agricultural products, belonging to the warm 

 and cool regions, side by side. Only on the north coast between 

 Alexandria and Tripoli is the rainfall sufficient for the Bedouins to 

 produce a barley crop. 



Thousands of years ago Egyptian agriculture was already 

 assisted through the yearly floods, which enabled the arable soil by 

 means of the red silt deposits that the Nile brought down during 

 the flood-time to grow produce. The distribution of the precious 

 water was made through a complicated system of artificially con- 

 structed basins and channels. Reclamation of desert land through 

 regular watering and cultivation of resisting plants was also under- 

 taken in those times, just as at present, although modern science 

 has latterly brought many improvements about in the carrying out 

 of this work. 



The yearly floods of the Nile are an important factor to everyone 

 in Egypt ; these are brought about by the tropical rains in the dis- 

 trict of the great Central African Lakes and of the Abyssinian High- 

 lands. The floods commence at Assuan at the end of June, in Cairo 

 at the beginning of July, and after a rapid rise they reach their 

 highest point in October. The subsequent decrease is very slow, 

 the river only reaches its lowest level again in April, May, or in- the 

 first days of June. From Roseires on the Blue Nile near to the 

 Abyssinian frontier, the flood usually takes seven weeks before it 

 reaches Cairo, namely, from Roseires to Khartoum 14 days, to 

 Assuan 22 days, and from there to Cairo 12 days. The daily speed 

 of the Nile current, when it is at low level, is 67 km., but at flood 

 times it reaches twice that speed. The Nileometer shows on an 

 average of many years the lowest watermark to be at the beginning 

 of June, the highest at the beginning of September. The difference 

 between the highest and the lowest level is 15 metres at Assuan, 

 8^ at Thebes, and 1\ at Cairo. Before the construction of the 

 large dam assured a water supply, drought and famine were the 

 result when the flood had been at any time only 1 metre less than 

 the normal 8 metres, whilst the additional rising of 50 cm. above' the 



