39 
Mr Tredgold on Ventilating Buildings, 
the other hand, persons rarely take the trouble to think for 
themselves ; and, most likely, because very little pains have been 
taken to reduce the subject to principles, or to render it acces- 
sible to those who would wish to be acquainted with it ; and 
more especially those who would wish to be able to distinguish 
quackery from science. 
The object of this paper is to give a concise view of tho prin- 
ciples of the art of managing heat, as far as regards warming 
buildings, showing the various modes of applying it ; but pre- 
ceded by those of the still more important subject, ventilation. 
O/^ Ventilating Buildings. 
1 do not know of any thing more grateful to the senses, or 
more essential to health, than pure and wholesome air ; nor any 
subject on which less care and less science has been bestowed. 
It seems an anomaly that can be explained only by the power- 
ful influence of habit, which leads us in the steps of our fore- 
fathers, while in other arts changes have been made which ren- 
der it necessary to improve the ventilation of our dwellings. 
For in their large mansions the wind was suffered to blow 
freely through them, and a current of air to circulate through 
the wide space between the pannelled wainscot and the wall.” 
It must be habit also that renders the constant attendance at 
the bench or the bar supportable in the noxious atmosphere and 
elevated temperature of a court of justice. It must be habit 
which makes the offensive effluvia of an hospital be disregarded 
by medical men, — for surely these are not necessary evils ; but 
before I visited hospitals, courts, manufactories, and poor-houses, 
for the express purpose of seeing how they were ventilated, I 
had no idea of the magnitude of these evils. All places are not 
equally ill-ventilated, for there are some where it is much more 
effectively done than in others ; and in a few cases I have ob- 
served that cleanliness has in some degree compensated for the 
want of fresh air. 
We owe much to the labours of Dr Hales on this interesting 
subject ; but most, if not all, of those who have attended to it 
since he wrote, have confined their attention to improving the 
means of admitting that quantity of air which Dr Hales had 
shown was injured by respiration. If such a change would have 
