nd it will be found that those rooms which are thus
enclosed and sheltered from the wind and rain, but left open to the
daylight, constitute the most cheerful sitting places in the houses.
Then, as rebuilding and alterations proceed, many houses will
gradually be remodelled--at least as regards some of their rooms--in
the same direction. Physicians will become increasingly insistent on
the necessity for admitting plenty of light into the abodes of the
sick, more particularly of families inclined towards consumption.

A very large trade will spring up during the twentieth century in
household cooling apparatus for use in hot climates. The colonial
expansion towards which all European races are now tending inevitably
means that very many thousands of persons whose ancestors have been
accustomed to life in cold or temperate climates, will be induced to
dwell in the dry and warm, or in the humid tropical regions of the
earth. It will be an important task of the British, Continental and
American machinists of the twentieth century to turn out convenient
pieces of apparatus which shall be available for ventilating houses,
especially during the night, and for reducing the temperature in them
to something approaching that which is natural to the inmates. The old
clumsy punkah will be replaced by circular fans keeping up a gentle
current of air with a minimum of noise or annoyance of any kind.

At present it is only in specially favoured circumstances that these
quiet-working circular punkahs can be actuated by mechanical force,
that is to say where a prime motor, or an electric current, or a
reticulated water supply for driving a suitable machine may be at
hand. In other situations the use of compressed air or gas may be
resorted to, and for this purpose small capsules, similar to those
already introduced for making soda water by the liberation of
compressed carbonic acid gas, will be found handy. For a very small
sum of money the householder will be able to purchase a sufficient
number of capsules to ensure motive power for his fan during a week of
hot nights.

A convenient form of small motor suitable for being driven by
compressed air or gases in this way is one in which a diminutive
turbine or other wheel is set at the bottom of a thin tube of mercury.
The capsule, being fastened to the lower end of this apparatus,
liberates at very short intervals of time bubbles of air or gas,
which, in the upward ascent, drive the whe