VENTILATION OF SEWERS AND DRAINS. 161 
air of one mile of nine inch sewer and two hundred and fifty house 
drains would be changed every twenty minutes. 
The foregoing is a description of the shaft and what the inventor 
claims to do with it. The trial will be an important one in con- 
nection with sewer ventilation ; the results will no doubt be made 
public on completion. 
The object to be aimed at in dealing with the question of sewer 
ventilation is motion, not only for the sewage but for the air, 
there should not be any resting place for either, and in the works 
carried out in connection with the sewerage system of the City and 
Suburbs this object is kept in view, foul gases should not be 
permitted to form, if the true principles of ventilation are 
observed, this would not take place. The introduction of currents 
of fresh air oxydizes the sewer air, prevents the fungoid growth | 
on walls of sewers and tends to reduce the humidity of the air in 
the same. 
The models shewn indicate the various forms of cowls &c. in use. 
A great improvement has been made, because the revolving ones. 
although very effective are liable to and do get out of order, and 
in sucha condition would be useless. The fixed induct does better 
work than the others and has not their disadvantages. 
The death rate of the City and Suburbs compares very favorably 
with that of other cities of the world ; I see no reason why a still 
further reduction should not take place when the older system 
of house drainage is eradicated, this however can only be a work 
of time. The work of reconstruction is increasing yearly,. old 
habitations are disappearing and are being replaced by large 
spacious warehouses and other buildings, which contributes very- 
much to the improvement of the health of the city. 
K—July 6, 1892. | 
“3 
= 
_ 
