1886.] NEW YORK ACADEMY OF SCIENCES. 45 



opportunity for the dissolved organic matters to oxidize, and to 

 be carried by subsidence along with the suspended mineral mat- 

 ters to the bottom. 



3d. Effectual filtration. And it should be noted that, when 

 the act of 1851 required the London companies to filter the 

 water, under very heavy penalties, the water referred to was that 

 taken from the Thames above Teddington lock, which water the 

 Commission had previously found to be "perfectly wholesome, 

 palatable and agreeable." Still more striking instances of the esti- 

 mate put upon filtration, as a process indispensable to the excel- 

 lence of city water supply, were frequently brought under my 

 personal observation, and some I shall mention later. 



4tii. The preservation of the water, after it has been filtered, 

 in covered storage reservoirs. 



The good effects of the act of 1851 speedily became apparent. 

 The water companies expended 3,500,000 pounds, with the re- 

 sult, according to the examinations of Prof. Hoff'man and Mr. 

 Blyth made in 1856, of bringing about "a very positive and con- 

 sideral)le diminution in the amount of organic matter. This, 

 though doubtless due chiefly to the removal of the intake above 

 the tideway of the Thames, was also attributed in great degree 

 to the considerable improvement which had taken place in the 

 collection, filtration, and general management of the supply of 

 water." 



But, fortunately, the public was not satisfied. In pursuance 

 of the recommendations of the Royal Commission of 1865, on 

 the pollution of rivers, the admission of sewage or any other 

 offensive or injurious matter into the Thames, or into any tribu- 

 tary, stream, or water course within three miles of its junction 

 with the Thames, was declared illegal, with heavy penalties. In 

 1866, 5,596 lives were destroyed in London by cholera, and al- 

 though this visitation was subsequently attributed to the polluted 

 water of the Ravensbourne and the foul unfiltered water from 

 the reservoirs at Old Ford on the river Lee, yet it so alarmed 

 the community that the Commission of 1866 was appointed to 

 make a far more extended inquiry than ever before, and to ascer- 

 tain what supply of unpolluted and wholesome water could be 

 obtained, by collecting and storing water in the high grounds of 

 England and Wales, either by the aid of natural lakes or by artifi- 

 cial reservoirs, at asuflicient elevation for the supply of London 

 and the principal towns of England. Now it is a well-known fact 

 that the recommendations of the very distinguished engineers 

 came to naught, so far as London was concerned, though they 

 are at present bearing fruit in connection with Manchester and 

 Liverpool. 



It is well worth our while to inquire why such was the case. 



