SEWAGE OF LONDON AND OTHER LARGE TOWNS. I51 
can be removed from ourselves to be placed under the 
noses of our neighbours I know not. Nor can I appreciate 
the wisdom of sacrificing the purity of the air inhaled by 
the inhabitants of Greenwich, Woolwich, Gravesend, &c., 
and the immense floating population,* in the doubtful at- 
tempt to make the air of the metropolis more wholesome. 
Sth. The air confined in the new drains will be a 
serious increase to the already enormous volume of putrid 
gases in the sewers. The government Referees make just 
and forcible remarks upon this evil. They state that “the 
effect of trapping the street gully-drains, without providing 
other ventilation of the sewers, is, that the noxious gases 
generated in the sewers are forced into the houses when 
the flow of sewage increases, the syphon-traps of water- - 
closets and sinks being the points at which the least resis- 
tance is presented to their escape from the sewers. To 
ebviate these evils, the plan has been partially adopted of 
providing in the middle of the street untrapped openings 
into the sewers. These openings must be endured until 
a better mode of ventilation shall be adopted, although 
the foul smells they emit are frequently very great nui- 
sances.”+ In addition to the cause assigned by the Re- 
ferees for the expulsion of the poisonous gases, I will 
mention the changes of atmospheric pressure. The fall 
of the barometer of one inch will of course occasion the 
liberation of one-thirtieth of the entire volume of gas. 
The smell so generally observed to arise in the neighbour- 
hood of drains before rain may probably be referred to 
this cause. It is also worthy of remark, that in winter the 
comparatively warm air of the sewers will have a tendency 
to rise. May not the greater mortality during that part 
of the year be partly attributed to this circumstance ? 
* “Tt is extremely undesirable in a sanitary point of view to cause sewage- 
water to be intermixed with sea-water.” — Messrs. Hawksley, Bidder and 
Bazalgette’s Report, p. 52. 
+ Report of Government Referees, p. 40. 
