DOMESTIC VENTILATION. 349 



the rooms supplied with air from above down the house 

 shaft, through the rooms, and out of the kitchen via the 

 winter heating-chamber, which now has its communication 

 with the outside air closed. 



Reverting to the first-named method, which I think is 

 better than the second, besides being less expensive, I must 

 say a few concluding words on an important supplementary 

 advantage which is obtainable wherever all the air entering 

 the house passes through one opening, completely under 

 control, like that of our heating-chamber. The great evil 

 of our town atmosphere is its dirtiness. In the winter it is 

 polluted with soot particles; in the dry summer weather, 

 the traffic and the wind stir up and mix with it particles of 

 dust, having a composition that is better ignored, when we 

 consider the quantity of horse-dung that is dried and pul- 

 verized on our roadways. All the dust that falls on our 

 books and furniture was first suspended in the air we breathe 

 inside our rooms. Can we get rid of any practically impor- 

 tant portion of this? 



I am able to answer this question, not merely on theo- 

 retical grounds, but as a result of practical experiments 

 described in the following chapter, in which is reprinted 

 a paper I read at the Society of Arts, March 19, 1879, re- 

 commending the enclosure of London back yards with a 

 roofing of "wall canvas/' or " paperhanger's canvas," so 

 as to form cheap conservatories. This canvas, which costs 

 about threepence per square yard, is a kind of coarse, 

 strong, fluffy gauze, admitting light and air, but acting 

 very effectively as an air filter, by catching and stopping 

 the particles of soot and dust that are so fatal to urban 

 vegetation. 



1 propose, therefore, that this well-tried device should be 

 applied at the entrance aperture of our heating chamber, 

 that the screens shall be well wetted in the summer, in order 

 to obtain the cooling effect of evaporation, and in the winter 

 shall be either wet or dry, as may be found desirable. The 

 Parliament House experiments prove that they are good 

 filters when wetted, and mine that they act similarly when 

 dry. 



By thus applying the principles of colliery ventilation to 



