oi Memoir on the Aden Reservoirs, [no. new series^ 
ly similar to, but on a much smaller scale than, the great dam of 
Mareb. 
The rocks within it hare 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 h^and 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. Sin 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. 8|. 
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. 8J. 
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 must all flow into the main channel, at some point of its 
course. 
No. 8 is a large reservoir through which the main aqueduct 
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