A, 
Prof. Hosking on Ventilation. 251 
The open fire may be made to give place to the close stove or 
to hot-air pipes, to hot-water pipes, or to steam-pipes—which 
make hot the air about them in aclose room without causing 
draughts. But the warmth obtained in pipes is costly under any 
circumstances. Air does not take up heat freely, unless it be 
driven and made to pass freely over the heated surface ; and there 
being little or no consumption of air, and consequently little or 
no draught, in connection with heated bodies, such as close stoves 
and hot pipes, the heat from them is not freely diffused, and is 
not wholesome. There is with all the expense no ventilation. 
Stoves and hot pipes are, moreover, exceedingly dangerous in- 
mates in respect of fire. Such things are the most frequent 
causes, directly or indirectly, of fires in buildings. Placed upon, 
or laid among or about the timbers and other wood-work of hol- 
low floors, and hollow partitions, and in houses with wooden 
Stairs, more conflagrations are occasioned by hot pipes and stoves, 
than by anything else, and perhaps more than all other things 
together. 
pen stoves with in-draught of air warmed by being drawn 
quickly (when it is drawn quickly) over heated surfaces may be 
Made part of a system of safe.and wholesome in-door ventila- 
tion; but to be perfect there must be also out-draught with power 
to compel the exit of spent or otherwise unwholesome air. But 
the arrangements for and connected with such stoves are special, 
and therefore costly, unless the buildings in which they may be 
employed, have been adapted in building to receive them. An 
in-draught stove may, however, be applied with great advantage 
as it regards the general warmth and ventilation, in the lowest 
Story of any house, if there be compelled out-dranght at the 
highest level to which it will naturally direct itself if it be not 
retained, so that the in-draughted air, tempered as it enters, may 
drawn out as it becomes spent, or otherwise contaminated. 
But this must be considered in all endeavors to effect in-door 
Ventilation, or the endeavor will fail. The air must be acted 
upon, and not be left, or be expected, to act of itself, and to pass 
tn or out as may be desired, merely because ways of ingress and 
egress are made for tt. Make a fire in a room, or apply an air- 
pump to the room, and the outer air will respond to the power 
exerted by either by any course that may be open to it, and sup- 
ply the place of that which may be consumed or ejected; but 
open a window in an otherwise close room and no air will enter; 
no air can enter, indeed, unless force be applied as with a bellows, 
hereby as much may be driven out as is driven im, with the 
effect only of diluting not of purifying. Even at that short sea- 
son of the year in which windows may be freely opened, unless 
Windows are so placed as to admit of the process of out-door 
_ Ventilation being carried on through them bya thorough di 
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