1851.] OF THE ROYAL INSTITUTION. 79 
sarily the spent or foul air. But make an opening into the chimney 
flue near the highest level in the room, that is to say, as near as 
may be to the ceiling, and if a draught be established between the 
window and the flue by this opening, the ventilation is complete ; 
that is to say again, if there be draught enough in the chimney 
flue from any cause to induce an up-current through it, or if there be 
motion of the external air to drive the air in at the window and 
force an up-current through the flue. 
Windows may not be put open in the long enduring colder 
season, however, and for the same reason in-draughts of the outer 
air by any other Ghannel are offensive and injurious. To open a 
door for the sake of air is but a modification of opening a window, 
and, if the door be an internal one, with the effect of admitting already 
enclosed, and, probably, contaminated air. Means of efficient in- 
door yentilation, 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 whole- 
some 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 economised. 
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 fcr 
the outer air directly to the fire in every apartment, to feed the 
fire, and indirectly to ventilate the room; way of egress in 
addition to the chimney 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 objection to its 
directness ceases. If however the warmth is imparted to it with 
foulness, the process does not fulfil the condition as to wholesome- 
ness, 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 bow the familiar 
fire of an apartment may be made to fulfil all the conditions necessary 
