inside, and _vice versa_. There is no direction in which a more
pressing need exists for the distribution of power in small quantities
than in regard to the ventilation of private and public edifices.

The circular fan, placed in the centre piece of the ceiling and
controlled by an electric switch on the wall, is the principal type of
apparatus applicable to the purposes of ventilation. As electric
lighting of dwelling-houses becomes more common, and ultimately almost
universal within cities, the practice will be to arrange for lighting
and for ventilation at the same time. But, unfortunately, the current
now principally employed for electric lighting and consisting of a
series of impulses, first in one direction and then in the opposite,
"alternating" with wonderful rapidity, is not well adapted for
driving small motors of the types now in use. One improvement in
domestic economy greatly needed in the twentieth century consists
in the invention of a really effective simple and economical
"alternate-current" motor. This is a matter which will be referred to
in dealing with electrical machines. That the problem will be solved
before many years have passed there is no good reason to doubt.

In the meantime many laudable endeavours are being made towards the
application of the pressure from water pipes to the purpose of driving
ventilating fans. The extreme wastefulness of power and of water
involved in this method of dealing with the difficulty may be
partially overlooked on account of the very small amounts required to
produce an effect in the desired direction; and yet there is no doubt
that a recognition of the wastefulness acts to some extent as a
deterrent to artificial ventilation. The benefits of the system are
not sufficiently obvious or showy to induce any class of people,
excepting physicians and persons fully acquainted with the principles
of hygiene, to sanction a material outlay upon the object. When an
exactly suitable alternate-current motor has been invented the
standard electric light installation will be practically one apparatus
with the ventilating fan, and the cost of the latter will hardly be
felt as a separate item.

In cooking there is in existing ordinary methods the same enormous
waste of heat as there is in the warming of rooms. Something, no
doubt, has been done in the direction of economy by the invention of
new and improved forms of stoves, but a great preponderance of the
heat generated i