316 



THE WATEK-Sb'l'I'LV OK TOWNS IN THE TltOl'lCS 



WKLL No. 7 

 Tompemture of water varied between 30-1 and 30- 7° C. usually was 30-4° C. 



Dale 



Strata cut off Average colony 



by I count 



cement per 1 c.c. 



+ 

 + 

 + 

 + 

 + 

 + 

 + 

 + 

 + 

 + 

 + 



+ 



9 

 .0 



9 

 ? 



7 



7-4 



7o 



9 

 5 



2-4 



3 



J>. coti 

 ' Flaginac " 



Chromogcnic 

 sugar-fermenting 

 j bacillus 



Note. — III all, some 250 separate coiuit.s and 63 qualitative examiaations were made up to this date 

 (April 23, 1909). 



Appendix 



From April, 1909, to the end of 1910, the following counts have been conducted and 

 the following results obtained : — 



Well No. 1. 4 counts. Average colony count = 7'5 per 1 c.c. 

 Well Nu. 6. 34 counts (2 false and discarded). 



Average colony count = 5 per 1 c.c. 

 Well No. 7. 30 counts (5 false and discarded). 



Average colony count = 7 per 1 c.c. 



A false count means one where there was evidently contamination from the pipe-line, 

 causing a marked but transitory increase in the number of colonies. 



It will be seen that the counts from the three are much the same, as was indeed to 



be expected, and that the water, from the point of view of the number of micro-organisms 



present in it, is of exceptionally good quality, answering to that usually derived from true 



deep wells. 



Notes on Distkibution 



Methods of distribution are, in the main, engineering questions, and in the case of the 

 Khartoum water-supply I only propose to consider the method employed in so far as it 

 has a hygienic bearing. 



The system adopted, and carried through without any reference to those responsible 

 for the public health, is that known as the "Dead-end." From the sanitary standpoint 

 the disadvantages of this system are that the water is liable to remain stagnant for 

 indefinite periods in the " dead-ends " of the pipes with the result that it deteriorates 

 in quality. These disadvantages are increased when, as in the case under discussion, the 

 water contains an excess of iron, for its stagnation favours the development of the 

 crenothrix fungus as well as of any deleterious or objectionable organisms wliich may 

 happen to be present. Although the chromogeuic, lactose-fermenting bacillus mentioned 



