306 



THK WATKU-SflTI.V OK TOWNS IN THIi TKOl'ICS 



Geological 

 conditions 

 point to the 

 possibility 

 of pollution 



" Tliey, liowever, appear to sliow that, apart from the presence of iron and manganese, 

 no serious objection can he raised from a purely clieniical point of view. 



" Should iron and manganese ultimately prove to be present in quantities large enough 

 to create difficulties, these v?ould in no way l)e insurmountable, and the question W'ould be 

 merely one of expense." 



Their recommendations are of special interest. They advised : — 



" 1. The cutting off of tho upper strata in the wells down to a certain depth. 



" 2. The iniproval of the compressed-air plant, so as to guarantee continuous working 

 and avoid contamination of the wells from tlie air-lift. 



" 3. A continuous pumping trial, extending over a period of at least a fortnight, 

 with regular measurements of the output and depression. 



" 4. A series of bacteriological and chemical tests made at suitable intervals throughout 

 the above trials. 



"If these tests give satisfactory results, so that regular pumiiint,' from the wells is 

 begun, the following might be proceeded to ; — 



" 5. A periodical bacteriological control. 



" 6. A regular chemical examination of the well-water with a parallel examination 

 of the Nile. 



" 7. The deepening of Wells Nos. 5 and 6 to about 200 metres. 



" 8. The boring of a new well at a point suggested and taking advantage of this 

 boring in order to obtain accurate information both as regards the various strata and as 

 regards the water carried by these." 



I may say that they were led to believe that the sandstone layers belong to the 

 Nubian sandstone— which is said to reach from Uganda to Assouan, and that they are 

 therefore extensive water-bearing strata fed mainly by seepage water from the Nile. 

 Further chemical examinations have led Dr. Beam and myself to regard this opinion as 

 correct. The deep water is probably derived from the White and not the Blue Nile, 

 and it is likely that it has travelled a long way underground. 



Messrs. Abel and Todd, who were put in possession of information regarding the 

 "Travertine" bed of which we were ignorant, made the interesting discovery that strata 

 of similar material crop out on the banks of the river east and south-east of the town — 

 it is therefore possible that this layer places the wells in direct communication with 

 the river, the porous bed extending some two miles or so from the site of the wells to 

 the river outcrops. This and the presence of the bed of bluish shale, W'hich was found 

 to exist immediately beneath the " Travertine " and to be about 6 metres in depth 

 would, in my opinion, adequately explain the results at first obtained, i.e. the evidence 

 of a mixture of pure deep well-water and of water which, from the English bacteriological 

 standpoint at least, was grossly polluted. Granting these conditions exist, could such 

 water travelling into the wells from the river cause disease under any known conditions? 

 I believe it might. There are native villages above the outcrops, and there is a certain 

 amount of boat and steamer traffic. Given enteric fever, dysentery or cholera, I do not 

 see why specifically contaminated river water might not reach the wells. It is true that 

 in the bed of bluish shale saprophytic organisms might successfully combat the pathogenic, 

 but we know that B. coli communis, at least in some of its forms, is not a very resistant 

 organism, and yet it was present in very small quantities of the water. In the case of 

 Nile water also one must not forget such a disease as dracontiasis, while the recent 

 confirmation of the correctness of the Mills-Eeincke phenomenon is another strong 

 argument in favour of obtaining as pure a water-supply as possible. At any r;',te, as will 



