226 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



the watersheds contributing to rivers from which supplies are 

 taken by pumping. The gathering-grounds included in the 

 576,000 acres from which water is collected into catchment 

 reservoirs are generally situated in thinly populated upland 

 districts, but, notwithstanding the sparseness of the population in 

 most of these areas, great difficulty is experienced in satisfying the 

 demands of modern hygienic science with respect to the degree of 

 purity to be maintained. The undesirability of allowing water for 

 domestic consumption to be polluted by human sewage has never 

 been seriously disputed, but as long as impurities were determined 

 and measured only by chemical analyses, the presence of matters 

 detrimental to health could seldom be quite conclusively proved. 

 The science of bacteriology has changed all this, and if the 

 standards of purity now exacted by the medical profession, based 

 upon the determinations of bacteriologists, are to be observed, 

 much more rigorovis methods must be adopted than have hitherto 

 been considered necessary to protect the streams and rivers from 

 contamination by pathogenic organisms. Efflarts made to prevent 

 fouling, by putting into operation the provisions of the Public 

 Health Acts, the Rivers Pollution Act, and the by-laws of con- 

 servators, have proved ineffective, and the results obtained have 

 been unsatisfactory. And in consequence of the inadequacy and 

 failure of these statutory provisions and by-laws, the authorities of 

 many large towns, such as Manchester, Liverpool, and Birming- 

 ham, and of many smaller towns, have been led to the conclusion 

 that the purity of their water-supplies can only be effectually 

 !;«ecured by themselves becoming the owners of the watersheds. 

 Acting on these convictions, they have applied to Parliament for 

 ])Owers to acquire the watersheds by agreement or by compulsion ; 

 and Parliament, having been satisfied as to the soundness and 

 wisdom of the conclusions arrived at, has readily granted the 

 necessary powers. The cases that have come to my own knowledge 

 in which compulsory powers for acquiring watersheds have been 

 obtained, amount to a total of 102,615 acres. It is probable that the 

 precedents set by these towns will be largely followed in the near 

 future, and here the important question arises. How are the areas 

 thus acquired to be utilised 1 It is evident that, in order to reduce 

 to a minimum the risks of polluting the water in a manner likely 

 to produce disease, the first object must be to limit the resident 

 population to the lowest number reasonably practicable. This 

 cannot be accomplished if agricultural operations are allowed to 



