44 TRANSACTIONS OF THE [NOV. 29, 



upper surface, so that the luliole cleaning operation necessary was 

 to scrape this surface off to a slight thickness, and, when it 

 had become too much diminished, to put on fresh sand. 



In accordance with these suggestions, the first hirge filter, 

 which had an area of one acre, was put into use by the Chelsea 

 Co. in 1829.* It worked well, so well indeed that it led to the 

 well-nigh universal practice of filtration in England. Our 

 failure to do the same in this country shows that in this re- 

 spect we are behind the age. 



But about the time of this first use of filters in England, the 

 disturbing ideas of modern sanitary science took their rise; 

 that unspeakable abomination, the domestic cesspool attached 

 to a city house, began to be abolished; drainage and sewerage 

 works were established, and the amount of impurities carried to 

 and fro under London Bridge was increased enormously. 



This agitation kept on growing until, in the year 1S34, the 

 engineer, Mr. Telford, recommended that the Thames should be 

 abandoned. This was not done, but in 1851 a Royal Commis- 

 sion, consisting of Profs. Graham, Miller, and Hoffman, recom- 

 mended that while the supply should still be drawn from the 

 Thames, the points of intake should be removed above the influ- 

 ence of tidal flow (i. e., above Teddington lock). They made 

 other recommendations which were incorporated into an Act 

 passed in 1852, regulating the water supply of the metropolis. 

 In this act the two clauses of greatest significance to us are, 

 first : That every storage reservoir within five miles of St. Paul's 

 should be covered ; and, secondly, That all water supplies for 

 domestic use should he effectually filtered, imless it is pumped 

 from wells direct into covered reservoirs. 



A mere statement of the law which was passed after a quarter 

 of a century of discussion by the most eminent engineers, chem- 

 ists, and law-makers of England, is a more emphatic testimony 

 to the fundamental importance of the provisions therein con- 

 tained than any argument I am able to make. 



This law led to certain results throughout England, which I 

 trust will become universal. These are: 



1st. The education of public opinion to such a point as to de- 

 mand sources of city water supply, actually and visibly free from 

 pollution. The wealthiest communities, like Glasgow, Man- 

 chester, and Liverpool, have deemed it a wise investment of 

 great sums of money to obtain sources absolutely free from sus- 

 picion and reproach. 



2d. The construction of large, and in some cases vast, reser- 

 voirs with the object, not merely of safety, but also of allowing 



* Royal ComiB. Water Supply, 1868. 



