more evil than good to the delicate inmates.

The grand art of ventilating houses is by some method that will empty
rooms of the vitiated air and bring in a supply of pure air _by small
and imperceptible currents_.

But this important duty of a Christian woman is one that demands more
science, care, and attention than almost any other; and yet, to prepare
her for this duty has never been any part of female education. Young
women are taught to draw mathematical diagrams and to solve astronomical
problems; but few, if any, of them are taught to solve the problem of
a house constructed to secure pure and moist air by day and night for
all its inmates.

The heating and management of the air we breathe is one of the most
complicated problems of domestic economy, as will be farther illustrated
in the succeeding chapter; and yet it is one of which, most American
women are profoundly ignorant.




IV.

SCIENTIFIC DOMESTIC VENTILATION.

We have seen in the preceding pages the process through which the air
is rendered unhealthful by close rooms and want of ventilation. Every
person inspires air about twenty times each minute, using half a pint
each time. At this rate, every pair of lungs vitiates one hogshead of