The most successful mode of ventilating a house is by creating a current
of warm air in a flue, into which an opening is made at both the top
and the bottom of a room, while a similar opening for outside air is
made at the opposite side of the room. This is the mode employed in
chemical laboratories for removing smells and injurious gases.

The laboratory-closet is closed with glazed doors, and has an opening
to receive pure air through a conductor from without. The stove or
furnace within has a pipe which joins a larger cast-iron chimney-pipe,
which is warmed by the smoke it receives from this and other fires.
This cast-iron pipe is surrounded by a brick flue, through which air
passes from below to be warmed by the pipe, and thus an upward current
of warm air is created. Openings are then made at the top and bottom
of the laboratory-closet into the warm-air flue, and the gases and
smells are pressed by the colder air into this flue, and are carried
off in the current of warm air.

The same method is employed in the dwelling-house shown in a preceding
chapter. A cast-iron pipe is made in sections, which are to be united,
and the whole fastened at top and bottom in the centre of the warm-air
flue by ears extending to the bricks, and fastened when the flue is
in process of building. Projecting openings to receive the pipes of
the furnace, the laundry stove, and two stoves in each story, should
be provided, which must be closed when not in use. A large opening is
to be made into the warm-air fine, and through this the kitchen
stove-pipe is to pass, and be joined to the cast-iron chimney-pipe.
Thus the smoke of the kitchen stove will warm the iron chimney-pipe,
and this will warm the air of the flue, causing a current upward, and
this current will draw the heat and smells of cooking out of the kitchen
into the opening of the warm-air flue. Every room surrounding the