e outside weather.
One man is sitting in church under a down draught from an open window
above him, while others, in different parts of the same building, may
be weltering in the heat and feeling stifled through the vitiated air.
In dwelling-houses the great majority of living rooms really have no
other effective form of ventilation than the draught from the
fireplace. The strength of this draught, again, is regulated to a very
large extent by the speed and direction of the outside wind.

In calm and sultry weather, when ventilation is most needed, the
current of air from the fireplace may be very slight indeed; while in
the wild and boisterous days succeeding a sudden change of weather,
the living rooms are subjected to such a drop in temperature and are
swept by such draughts of cold air that the inmates are very liable to
catch colds and influenza. Hence has arisen in the British Islands,
and in the colder countries of Europe and America, the very general
desire among the poorer classes to suppress all ventilation. Rooms are
closed at the commencement of winter and practically remain so until
the summer season. Many people whose circumstances have improved, and
who pass suddenly from ill-ventilated houses to those which have
better access to the outside air, find the change so severe upon their
constitutions and habits that they give a bad name to everything in
the shape of ventilation. Meanwhile the dread of draughts causes
people to exclude the fresh air to such an extent that consumption and
many other diseases are fostered and engendered.

All this arises mainly from the very serious mistake of imagining that
it is possible to move air without the exercise of force. In the case
of the draught caused by a fire no doubt an active force is employed
in the energy of the heated air ascending the chimney, and in the
corresponding inrush. This latter is usually drawn from below the
door--the very worst place from which it can be taken, seeing that in
the experience of most people it is by getting the feet chilled,
through draughts along the floor, that the worst colds are generally
contracted. Fireplaces are not unusually regarded as a direct means
for ventilation, and with regard to nearly all the devices commonly
adopted in houses and public buildings, it may be said that they lack
the first requisite for a scientific system of renewing the air,
namely a source of power by means of which to shift it from outside to