president's address SECTION I. 181 



Enfants assisfes, and other hospitals and asj'lums, that arrondisse- 

 ment, Avith a density of population only one-third of that of the 

 IV. arrondissement, in which the Hotel de Ville is situated, has a 

 rate of mortality that is quite as high. 



With regard to drying the air of a town, it is often effected by 

 the work done in laying the ordinary sewers, and shown to be 

 effected by an immediate fall in the death rate from phthisis and 

 diseases encouraged by excess of humidity. Where the land 

 drainage is not so efPected it should be done by special works. 



The questions of the system of sewerage and of sewage disposal 

 can receive no satisfactory specific answers applicable to all places 

 and circumstances. The answers must depend upon so many 

 different conditions and contingencies that those of each place 

 must be important factors in deciding upon the answer to be given 

 for the place. But there are certain requirements that must be 

 fulfilled ill all places. The sewers must be well and economically 

 built, large enough to do their duty, but not too large ; they must 

 be self-cleansing, or have special means of being cleansed ; and 

 they must be well ventilated ; and the sewage must be disposed of 

 without causing a niiisance. The proper fulfilment of all these 

 requirements, especially the last, is often no easy task. Were this 

 the proper arena for such a discussion, and were ihere time at our 

 disposal. I should be inclined to maintain the following theses ; — 



1. With regard to the Sizes of Sewers. — That they should be no 



larger than fully sufficient to carry off in the hour of 

 greatest daily flow the sewage and so much of the rainfall 

 as could not be excluded during that hour, as they would 

 thus secure greater efficiency of action with greater 

 economy of construction, better ventilation with a smaller 

 supply of air, and better flushing with a smaller supply of 

 water. 



2. With rfspect to the Ventilation ></ Servers. — That the best 



mechanical means for effecting it are those making use of 

 the force of the wind as motive power. 



3. With relation to Seivage Disposal. — That our present experi- 



ence shows that where it can be safely discharged without 

 treatment, as, for instance, into the sea, such discharge is 

 the most economical method : that w,here such discharge 

 is impracticable, the purification of the sewage before dis- 

 charge by some chemical agent, such as ferozone, that 

 does not add much to the bulk of the deposited sludge, is 

 the most economical method of disposal. 

 With regard to street construction, the principal object to be 

 attained from a sanitary point of view is to have a surface easily 

 kept clean. From this point of view an asphalted roadway is the 

 best, and a macadamised one, if the road be made at all, the worst, 

 as virtually only offering the choice of having the air polluted by 



