18 
POPULAR SCIENCE REVIEW. 
The air of London is dirty and impure enough, but what 
is it as it passes from your window crevices, the key- 
holes of your doors, and the tiles of your house ? Dirtier and 
more impure than ever. If you say it is not impure, you 
are wrong* ; if you know it is impure and talk of the ventila- 
tion of your house, it is cant. 
I know of no means by which a house can be naturally 
ventilated without superintendence, or machinery. The system 
of pumping into public buildings warm pure air, and pumping 
out the impure air is to be commended, as it secures by the 
same machinery both warmth and pure air. Whether any- 
thing of this kind can be done for private houses is at present 
very questionable. In the meantime, houses ought to be 
built so that an ordinarily intelligent person, who understands 
that hot air ascends and goes out at the upper apertures of 
a room, and that cold air comes in from below, can so arrange 
that there is a perpetual flow of air through the room without 
creating cold by draught. This can generally be done in 
rooms where the window sashes come down from the top in 
two sides of a room, or in one side where a door opens at 
the other. But, alas ! how many houses are thus constructed ? 
Not one in a hundred in town or country. When they are 
so constructed, the sashes are not let down from the top. 
The bed-rooms, which have been closed up all night, are in- 
dulged with a small quantity of fresh air by a little opening 
from below. The consequence of all this closing of doors and 
windows is sickness. The children are ill in the nursery, the 
servants are ill in the kitchen, and the master and mistress are 
ill in the drawing-room. The source of this sickness is easily 
understood, if you recollect how large a portion of time the 
inhabitants of houses spend indoors, and it is precisely those 
who take least exercise or go out least that suffer most. 
The same arrangements in houses that secure the influx of 
oxygen from without, and the efflux of the carbonic acid from 
within, also secure the escape of those solid particles which 
are so injurious when contained in any considerable quantity 
in the air. It is a well-known fact, that you may so dilute 
the poison of various fevers, as they escape from the bodies of 
those attacked, that no one shall be injured by it. If you 
place one patient with fever in a large ward, no other patient 
gets the disease, but if you place several fever patients in the 
same room, then every person that enters may catch the 
fever. So it is with the poisons of drains and cesspools. If 
they be well diluted in the open air nobody suffers, but let 
them concentrate themselves in a room and destruction takes 
place. I say safety is secured by ventilation in houses other- 
wise danererous, but no wise man would allow his drains or 
