401 
VENTILATION AND VENTILATORS. 
By THE EDITOR. 
I F we may be permitted to define cant as the current expression 
of unintentional insincerity, we believe that there is no species 
of cant more general than that which people talk about ventila- 
tion. Go where we may, whether into the houses of the wealthy 
or into the miserable dwellings of the poor, we hear the same 
cry about ventilation and its advantages ; but in no cases, or at 
least in few, do we see any reason to think the cry a genuine one. 
How many people tell us of the healthy influence of pure fresh 
air, but how few ever take proper steps to introduce it into 
their houses ! How seldom do we see anything like a rational 
system of ventilation in public buildings ; and where are the 
private dwellings in which vitiated breathing-air is not abun- 
dantly present ? It is not our intention, in the observations we 
are about to make, to dwell upon the elementary facts that human 
beings contaminate air by the exhalations from their lungs, and 
that the respiration of such air is eminently injurious to health. 
These have already been fully and forcibly pointed out by Dr. 
Edwin Lankester.* Indeed, we think it is now pretty generally 
admitted that the influence of a greater proportion of carbonic 
acid in a breathing atmosphere than that of *6 per 1000 is both 
adverse to comfort and obnoxious to health. We purpose, 
therefore, to lay before our readers, as clearly and withal as 
briefly as possible, the principles on which ventilation should be 
conducted, and to describe the more important methods by 
which such thorough ventilation as can be adopted may be 
achieved. 
At the outset we may state, in very general terms, that the 
word ventilation simply expresses the passage in and out of air. 
The regulation of this inlet and outlet, in such a manner as to 
be least productive of discomfort and disease, is one of the 
highest aims of hygiene. We may add, too, that it is by far its 
most difficult problem. In an ordinary room it is clear that air 
is constantly entering and leaving by some of the apertures in 
* See Popular Science Review , vol. iii. p. 6. 
