82 NOTICES OF THE MEETINGS [May 28, 
would enter by the wmdows of the same house, it may be unnecesary 
to enter into any inquiry as to the condition of the air heretofore 
spoken of as fresh and pure. ‘‘ Fresh” and ‘‘ pure”’ applied to air 
must be taken to mean the freshest and purest immediately obtainable, 
and that will be the same whether it be drawn in through a grated 
hole in a wall, or by a glazed opening close by it in the same wall. 
But it is a fair subject for inquiry whether,—speaking in London to 
Londoners,— the air about our houses in London is as pure,—or as 
free from impurity,— as it might be. 
The out-door ventilation of large towns may be taken to be more 
complete above the tops of the houses and of their chimneys than it 
is or, perhaps, can be among and about the houses ; — the processes 
of Nature are there not only unchecked, but are in fact aided by the 
heat thrown up by the chimneys into the upper air, and impurities 
which can be passed off by chimney flues, will be more certainly 
and more effectually removed and changed by Nature’s chemistry, 
than if they are kept down to fester under foot and to exhale in 
our streets and about our doors and windows. 
At this time every endeavour is made to provide for removing from 
our dwellings all excrementitious matter, and all soluble refuse, by 
drains into sewers, and so by the sewers to some outfall for discharge. 
The drain necessarily falls towards the sewer, and the sewer again 
to its outfall, and the sullage or soil drainage being rendered liquid 
thus passes in the usual course. But the usages and the neces- 
sities of civilized life cause a large proportion of the liquid refuse 
from dwelling-houses to pass off in a heated state, or to be 
followed by hot water arising from culinary processes, and from 
washing in all its varieties. The heat so entering the drains causes 
the evolution of fetid and noxious gases from the matters which go 
with, or have gone before, the hot water; and with these gases 
house-drains almost always, and sewers commonly, stand charged. 
They are light fluids and do not go down with the heavy liquid 
matters from which they have been evolved, but they seek ta rise, 
and constantly do rise in almost every house through imperfections 
or derangements of the flaps and traps which are intended to keep 
them down, but which only, when they do act, compel some of the 
foul air to enter the sewers, and there to seek outlet to the upper 
air which they find by the gulley gratings in the streets. 
It can hardly be said perhaps that too much attention has been 
given of late to the scour of sewers by water; but it is most certain 
that too little attention has been given to the considerations last 
stated, for nothing has been done to relieve the drains and sewers 
of their worst offence. The evolution of foul and noxious gases in 
the drains is certainly not prevented by scouring the sewers. In 
the mean time the poison exists underfoot, and exudes at every 
pregnable point within and about our houses, and it rises at every 
grating in our streets, though the senses may become dull to them 
by constant suffering. 
