HILLS NORTH OF ADEN. 25 



made near the river course^ in the vicinity of which the supply of water 

 is probably greatest^ on account of the underground flow of the stream. 



One disadvantage of such deep wells would be, that if through 

 pumping, the level of the water in them stood considerably lower than 

 the normal water-level of the locality, the existing village wells of the 

 neighbourhood would undoubtedly be laid dry. 



In suggesting one or more such wells, I would not be understood 

 as advocating them, as superior to the schemes already proposed for the 

 supply of Aden. I merely point out that the town can be supplied in 

 this manner, and that it is a means worthy of consideration, leaving 

 the relative merits of the different proposals to future and more detailed 

 investigation. 



From Majhafa, I marched nearly due north to the foot of the hills, 



but on account of the disturbed state of the 

 Hills north of Aden. 



country, 1 was unable to enter them. The sum- 

 mits of the main range (Jibal Shiap) which are marked on Dr. Carter^s 

 sketch map of the south-east coast of Arabia as 6,000 feet high, are fully 

 10 miles beyond the most southern outliers, the intervening space being 

 occupied by detached hills, and wastes of blown sand. The section in 

 the outermost range of hills is as shewn in the sketch given on Plate B. 

 The limestone is not less than 600 or 700 feet thick, and may be much 

 more, as time did not permit me to visit the beds a. It is of a light 

 grey color,* in beds of moderate thickness, an occasional band of flaggy 



* The following are two analyses of this limestone by Mr. A. Tween, from which it will 



be seen that the rock is nearly pure carbonate of lime. For hydraulic purposes, lime made 



from it would require mixture with some material, like the pumiceous tufa of Aden, which 



is now used for the purpose mixed with burned coral. No. 1 is a light grey rock j No. 2 



one of a darker shade. 



No. 1. No. 2, 



Loss on ignition ... ... ... ... ... ... '8 ... 2' 



Insoluble ... ... ... ... ... ... ... "4 ... 2-95 



Besidue— Carbonate of lime, with iraces only of magnesia, 



alumina, iron and phosphoric acid ... ... ... 98'8 ... 95'05 



100 ... 100 

 No. 2 contains most magnesia and iron, but less than 0*3 per cent, of either. 



D ( 281 ) 



