April—June, 1857.] Memoir on the Aden Reservoirs. 35 



flows ; it was very much destroyed, one wall having been forced in, 

 either from the pressure of water from without, after the tanks and 

 aqueducts above it became ruins, or by the water finding its way in- 

 side the masonry and sapping its foundations. It has however 

 been repaired, and I am sanguine that it will prove water-tight. 



Thus far only the series is complete, beyond, the main aqueduct 

 has not been finished, though it is in course of construction, and 

 the other tanks, which are finished, have not been united. 



One of the most remarkable is No. 11, which is a double tank 

 situated below a deep rift in the hill, down which a great volume of 

 water flows, but as if to make sure of its being filled, the drainage 

 of the hill side behind it, is conveyed into it by an aqueduct lead- 

 ing through a small hole in the rock, not larger than a man's head. 

 The entrance to this tank was originally domed, and contained an 

 inscription which has been removed, the dome has been restored. 



The other tanks which have been restored, require no notice. 



Appendix B is a statement of all the remaining reservoirs which 

 have been discovered, some of them are cleared out and nearly com- 

 pleted, others are in course of restoration, the rest have not been 

 commenced : of these immeasurably the finest is that marked I. It 

 is nearly a cylinder of one hundred and forty-eight feet in diameter 

 but the depth has not yet been ascertained, about twenty-four feet 

 have been cleared out, but the bottom has not been reached : into 

 this reservoir, the overflow of all the tanks from No. 1 to 10, in table 

 A and from A to H in Table B and probably several others, will meet. 



It may be imagined that in so arid a spot as Aden, so many tanks 

 are useless and can never be filled, but I have known many falls of 

 rain during my residence here, which would have filled them all, 

 and many more had they existed. 



I regret that I am unable to delay the printing of this memoir, 

 until a plentiful fall of rain, which may be expected about this sea- 

 son, shall have tested their value. 



But whether they all prove water-tight or no, it is hardly possible 

 to over estimate the value of these reservoirs in a place like Aden, 

 which with a population of 25,000 souls, has a daily supply of sweet 

 water not exceeding 15,000 gallons. 



