BY THE HON. W. F. TAYLOR, M.D., ETC. 31 



for cities a water supply from sparsely inhabited districts, where 

 the chances of pollution by raw sewage are minimised. 



Where no rivers, streams, lakes or gathering groimds for 

 the formation of artificial reservoirs are available, wells become 

 the only source from which a water supply is obtainable. Of 

 the rain descending upon the ground, part percolates through 

 the soil until arrested by impermeable strata. This gives rise to 

 what is termed underground water, and in sinking wells this is 

 the water first met with. Large supplies of good water may be 

 obtained in this way in localities where the impervious strata 

 form a basin, and arrest the flow of the underground water 

 through the porous underlying strata towards the nearest water- 

 course or to the sea. Water obtained from wells contains a 

 greater or less quantity of mineral matter dissolved from the 

 soil through which it has percolated, both from the surface and 

 through porous strata on its way to its outlet in the sea or 

 nearest watercourse. It is obvious, therefore, that well water is 

 very liable to contamination from leaky sewers, cesspits or dung 

 heaps, for although the leakage may not be direct into the well — 

 every precaution having been taken to minimise such an occur- 

 rence — it may take place into the underground water within the 

 area from which the well draws its supply, and thereby serve as 

 a source of danger. The diagram now shown illustrates the 

 manner iia which this contamination may occur. Great varia- 

 tions in the level of this underground water are brought about 

 by wet and dry seasons — in dry seasons the level becomes 

 lower, to be raised again by rainfalls. 



Many instances may be given of the manner in which wells 

 have become contaminated by sewage, and the water used from 

 them has given rise to disease. I will content myself by citing 

 one, which is perhaps among the most recent on record. 



An outbreak of typhoid fever occurred at Worthing, 

 Sussex, in April, 1893. Dr. Thompson, Inspector of the Local 

 Government Board, investigated the cause of the outbreak, and 

 in doing so he had to set aside all known causes of typhoid, such 

 as milk, sewerage, drainage, &c., other than water, but only 

 after a careful study of their possible relationship to the disease. 

 The water supply of Worthing is obtained from three wells, with 

 three headings, two headings serving as connecting tunnels 



