Professor Hosking on Ventilation. 305 



and, probably, contaminated air. Means of efficient in-door venti- 

 lation must therefore be independent of windows and doors ; and 

 the means should be such as will lead to a result at once wholesome 

 and agreeable. 



Many plans Have been suggested, and some have been carried 

 into effect, of warming air, and then forcing it into or drawing it 

 through buildings, and, in the process of doing so, removing the foul 

 or spent air from the apartments to which it may be applied. Some 

 of these plans are more and some are less available to wholesome and 

 agreeable in-door ventilation, but even the best are rather adapted 

 to large apartments, such as those of hospitals, churches, theatres, 

 and assembly-rooms, than to private dwelling-houses in which the 

 rooms are small and labour and cost are to be economized. 



Plans have been proposed, too, for the economical ventilation of 

 dwelling-houses ; but they seem to be all in a greater or less degree 

 imperfect. Ways of access are provided in some cases for the outer 

 air directly to the fire in every apartment, to feed the fire, and indi- 

 rectly to ventilate the room ; way of egress in addition to the chim- 

 ney opening and the chimney flue being sometimes provided for the 

 spent air of the room ; sometimes, indeed, as before indicated, by an 

 opening into the chimney flue near the ceiling. A direct in-draught 

 of cold air is not agreeable, and it may be pernicious, but if the outer 

 air become warm in its way to the inmates of the room, the objec- 

 tion to its directness ceases. If however the warmth is imparted 

 to it with foulness, the process does not fulfil the condition as to 

 wholesomeness, and this is the case, when the outer air is admitted 

 at or near to the ceiling to take up warmth from the spent and heated 

 atmosphere of the higher levels. Having undergone this process, 

 it is not the fresh air that comes warmed to the inmates, but a 

 mixture of fresh and foul air that cannot be agreeable to any inmate 

 conscious of the nature of the compound. 



The endeavour on the present occasion was to show how the 

 familiar fire of an apartment may be made to fulfil all the condi- 

 tions necessary to obtain in-door ventilation, to the extent at least 

 of the apartment in which the fire may be maintained, and while it 

 is maintained. 



A fire in an ordinary grate establishes a draught in the flue over 

 it with power according to its own intensity, and it acts with the 

 same efl'ect, at least, upon the air within its reach, for the means 

 which enable it to establish and keep up the draught in the flue. 

 The fire necessarily heats the grate in which it is kept up, and the 

 materials of which grates are composed being necessarily incom- 

 bustible, and being also ready recipients and conductors of heat, 

 they will impart heat to whatever they may be brought into con- 

 tact with them. 



It is supposed that the case containing the body of the grate is 

 set oh an iron or stone hearth in the chimney recess, free of the 



