audience can
even listen to a physiological discourse on the fatal effects of
impure air without experimentally knowing that they are listening to
solemn truth; while as to the dwelling-houses, the homes of the dear
people, it requires no bloodhound's scent to distinguish them one from
another! The moment the front door is opened to me, I am assailed by
the odor peculiar to the establishment. It may be tuberoses or garlic,
mould or varnish, whitewash, gas, lamp-smoke, or new carpets, a
definite and describable or an indefinite and indescribable fragrance,
but it is sure to be something besides pure fresh air.

[Illustration: SHINGLING.]

Let me give you first a suggestion for summer ventilation. Did you
ever shingle the south side of a barn on a calm, hot, sunny day in
July, thermometer at ninety degrees in the shade? Did you ever lay
your hand on a black slate or tin roof exposed to the direct rays of a
midsummer sun? Have you ever, at the close of some hot, labor-spent
day in August, sat out of doors until the evening air became
deliciously cool, and then climbed to your attic dormitory, there to
spend a sleepless night in perspiration and despair, anathematizing
the man who built and the fate which compelled you to occupy such a
chamber of torment?

Now, there is no good reason why the rooms immediately under the roof
of a house should be any more uncomfortable on account of heat than
those of the first story. Nay, more, by the simplest application of
common-sense, these upper rooms may be so coolly ventilated that the
hotter the sun pours his rays upon the roof the more salubrious shall
be your palace in the sky. And this I call a triumph of genius, making
the seemingly destructive wrath of the elements to serve and save us.

M. Figuier tells us with just how many hundred thousand horse-power
the sun, by the caloric of its beams, operates upon the surface of the
earth. I cannot tell precisely how much force is spent upon the roofs
of the houses that cover so much of the good mother's bosom in certain
localities, but I know that it is wonderfully great, and that rightly
controlled it will make the space immediately under these roofs cool
instead of hot.

And this is the way to cause the heat of a burning sun to cool the
attic chamber: Make the space between the rafters on the sunny sides
of your building as smooth and unobstructed as possible. Arrange
openings into the outer air at the lower end of each, simpl