84 Memoir on the Aden Reservoirs, [no. 3, new series, 



ly similar to, but on a much smaller scale than, the great dam of 

 M&reb. 



The rocks within it have been coated with chunam to prevent 

 leakage, above it is another large but natural tank which retains 

 water during the greater part of the year, this was formerly inac- 

 cessible, but steps have now been cut, and hand rails and iron stan- 

 chions inserted in the rock, to facilitate communication with it. 



No. 2 is situated lower down the valley, on the west or left side, 

 and at some distance from No. 1 , the intermediate space being oc- 

 cupied by the Tawela well ; formerly no communication existed be- 

 tween them, but a broad paved aqueduct has now been constructed 

 to answer the double purpose of preserving the water which may 

 overflow from No. 1, and the drainage of the intermediate rocks. 



No. 3 is immediately adjoining No. 2 and connected with it by 

 means of a sluice near the top of the wall. 



No. 4 is connected with No. 3 in the same manner, and its over- 

 flow is conducted into a large aqueduct thirteen feet in breadth, 

 which runs down the centre of the valley, round the Bir Khalad 

 into No. 8J. 



No. 5 is situated on the east or right hand side of the valley, 

 near No. 1, and opposite No. 3, it is extremely fantastic in con- 

 struction, and has two deep wells in the centre, one of which is 

 thirty-five feet in depth. 



No. 6 is connected with the preceding by means of a slit in the 

 rock which conveys the water into it. 



No. 7 a tank of very similar construction, the overflow of which 

 is carried by a branch aqueduct across the valley, into the main 

 aqueduct, in which is situated the small tank No. 8|. 



No. 8J is, as above said, a small tank in the main aqueduct, 

 built for the purpose of preventing the soil and stones washed down 

 by the rain from falling into, and injuring the large one beyond it 

 (No. 8) : here the overflow of all the other tanks above it, meet so 

 that no water descending from the hills can by any possibility es- 

 cape, it jnust all flow into the main channel, at some point of its 

 course. 



No. 8 is a large reservoir through which the main aqueduct 



