726 THE ECONOMIC CONQUEST OF AFRICA BY THE RAILROADS. 



This military line is interesting for many reasons. It has two 

 branches, one through the Nubian desert and the other extending 

 into the province of Dongola. Although laid with extreme repidity, 

 the average expenditure per mile did not exceed $15,200. Of course 

 there were practically no great feats of engineering involved. At 

 one place there is a straight level stretch of 45 miles. The declivities 

 average less than 0.008 m. and, excepting the Atbara bridge, some 

 1,200 feet long, there was no particular difficulty of construction. 



But the hasty manner in which the road was built entails constant 

 repair and necessitates a series of supplementary Avorks, v,^hich will 

 increase somewhat the initial cost per mile. 



Fig 3.— Egyptian system. 



The roads south of Wady Haifa already furnish very useful data 

 concerning railway operations in a desert country. On them it is 

 possible to make observation on the rapid wearing away of the rails 

 by the sand and the destruction of the cross-ties by neuptera. "Water 

 trains are found necessary, since in the whole stretch of 237 miles 

 between Wady Haifa and Abou-Hamed water could be reached but 

 twice — then by boring, in one case 858 feet and in the other 975 feet. 



At the point last named, although the summer heat is excessive, 

 there is a roundhouse for locomotives, with a shop for small repairs. 

 The main shops at Wady Haifa and Shendi have the very difficult 



