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self-ventilating. Ventilation, as this article shows, consists in two
things,--a perfect and certain expulsion from the dwelling of all foul
air breathed from the lungs or arising from any other cause, and the
constant supply of pure air.

One source of foul air cannot be too much guarded against,--we mean
imperfect gas-pipes. A want of thoroughness in execution is the sin of
our American artisans, and very few gas-fixtures are so thoroughly made
that more or less gas does not escape and mingle with the air of the
dwelling. There are parlors where plants cannot be made to live, because
the gas kills them; and yet their occupants do not seem to reflect that
an air in which a plant cannot live must be dangerous for a human being.
The very clemency and long-suffering of Nature to those who persistently
violate her laws is one great cause why men are, physically speaking,
such sinners as they are. If foul air poisoned at once and completely,
we should have well-ventilated houses, whatever else we failed to have.
But because people can go on for weeks, months, and years, breathing
poisons, and slowly and imperceptibly lowering the tone of their vital
powers, and yet be what they call "pretty well, I thank you," sermons on
ventilation and fresh air go by them as an idle song. "I don't see but
we are well enough, and we never took much pains about these things.
There's air enough gets into houses, of course. What with doors opening
and windows occasionally lifted, the air of houses is generally good
enough";--and so the matter is dismissed.

One of Heaven's great hygienic teachers is now abroad in the world,
giving lessons on health to the children of men. The cholera is like the
angel whom God threatened to send as leader to the rebellious
Israelites. "Beware of him, obey his voice, and provoke him not; for he
will not pardon your transgressions." The advent of this fearful
messenger seems really to be made necessary by the contempt with which
men treat the physical laws of their being. What else could have
purified the dark places of New York? What a wiping-up and reforming and
cleansing is going before him through the country! At last we find that
Nature is in earnest, and that her laws cannot be always ignored with
impunity. Poisoned air is recognized at last as an evil,--even although
the poison cannot be weighed, measured, or tasted; and if all the
precautions that men are now willing to take could be made perpetua