Professor Hosking on Ventilation. 307 



The mode referred to of warming and ventilating apartments by 

 their own fires is most easy of application, and in houses of all kinds, 

 great and small, old and new, and as the warmth derived from the 

 fire in any case, comes directly by the in-draughted air, as well as 

 by radiation of heat into the air of the apartment, fuel is econo- 

 mized. If the register flap be made to open and shut, by any 

 means which give easy command over it, so that it may be opened 

 more or less according to the occasion, and this be attended to, the 

 economy will be assured ; for it is quite unnecessary to leave the same 

 space open over the fire after the steam and smoke arising from 

 fresh fuel have been thrown off, as may be necessary immediately 

 after coaling. The opening by the register valve into the flue may 

 be reduced when the smoke has been thrown off, so as to check the 

 draught of air through the fire, and greatly to increase the draught 

 by the upper opening into the flue, to the advantage of the ventila- 

 tion and to the saving of fuel, while the heat from the incandescent 

 fuel will be thereby rather increased than diminished. 



Moreover the system being applicable in the cottage of the 

 labourer, as fully and easily as in the better appointed dwellings of 

 those who need not economize so closely as labouring people are 

 obliged to economize, the warmed air about the grate in a lower 

 room may be conveyed directly from the air-chamber about the 

 grate by a metal or pot pipe, up the chimney flue, and be delivered 

 in any upper room next to the same flue and requiring warmth and 

 ventilation, the process of ventilation applied to the lower room being 

 applicable to the upper room also. 



The indicated means by which winter ventilation is obtained are 

 not of course equally efficient in summer, for the draught of the fire 

 is wanting ; but the inlet at the low level for fresh air, and the out- 

 let for the spent air at the upper level continuing always open, the 

 heat which the flue will in most cases retain through the summer 

 aided by that of the sun's rays upon the chimney top, secures a 

 certain amount of up-draught, which is not without its effect upon 

 the in-draught by the lower inlet even when windows and doors are 

 shut. 



While it is obvious that the air drawn into any house for the 

 purpose of in-door ventilation need not be other than that which 

 would enter by the windows of the same house, it may be necessary 

 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 obtain- 

 able, and that will be the same whether it be drawn in through a 

 grated hole in a wall, or by a glazed opening closed 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. 



