482 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1908. 



springs in the neighborhood of Philse Island at the head of the first 

 cataract, although this legendary source can not have coincided with 

 their experience, since from very early times they were acquainted 

 with its Nubian valley, and therefore knew that the true sources lay 

 to the south of this again. But these southern regions were poor and 

 inhospitable as compared with the fertile flood plain and delta of 

 Egypt, and beyond raiding them for slaves and cattle and levying a 

 tribute upon the inhabitants, the Egyptians interested themselves but 

 little in the upper reaches of the river. 



In the course of the eighteenth century the sources of the Blue. 

 Nile were discovered, and the cause of the annual flood was correctly 

 determined to be the summer rainfall on the table-land of Abyssinia. 

 In the nineteenth century the A\"liite Nile was traced to the lakes of 

 the equatorial plateau, and the geography of its basin was sufficiently 

 elucidated to enable Lombardini, in 18G5, to sketch out the broad lines 

 of the hydrography of the Nile. 



During the last quarter of the nineteenth century the rapid increase 

 of prosperity in Egypt, wdiich was due to the establishment of order 

 in the country and the introduction of administrative reforms, di- 

 rected attention to the lower reaches of the river, while the Mahdist 

 rebellion closed the Sudan to travelers. The irrigation of the country 

 had been organized and developed so that not only were large areas of 

 waste land brought under cultivation, but land which formerly bore 

 but one crop in the year, produced two and even three when the water 

 of the Nile was supplied regularly throughout the year instead of at 

 the time of the inundation only. But at the same time that the 

 demands of the cultivator have been constantly increasing, Egypt has 

 experienced an unusual shortage of water, caused b}'' the long series 

 of exceptionally low floods which have occurred of late years, one 

 alone since that of 189G having been above the average, so that great 

 difficulty has been experienced in furnishing the quantity of water 

 needed for the crops. 



The valuable cotton crop, which is sown in March and April, and 

 which is picked in September and October, needs a regular supply of 

 water in May, June, and July, when the river is at its lowest and the 

 flood has not yet arrived; consequently the irrigation engineers have 

 been compelled to husband the water in every available vv ay that could 

 be devised in order to meet as far as j^ossible the requirements of the 

 early summer months. But a larger supply was urgently needed, and 

 directly Omdurman had been taken and the Mahdist rebellion had 

 been crushed, the investigation of the upper Nile was vigorously 

 pushed forward in order to see how the low-stage supply of the river 

 could best be increased. To these needs we owe the great addition to 

 our knowledge of the regimen of the Nile and its tributaries which 

 has been gained during the last eight years. 



