The true northerner. [volume] (Paw Paw, Mich.) 1855-1920, 1885-09-10

Interesting foc0 AD0ut Ar
There IL always o wind at the burn
ing of building, because the heated
air rises and the cold air PUSHES In TO
take its place.
Sound depends on the presence of
air, because the air is put in motion by
the action of the body producing
sound, in the same way as pool Of
water is disturbed by throwing in o
stone The vibrations of the air grad
ually extend themselves until they
reach the ear, and communicate the
idea of sound to the mind.
This is easily illustrated by clasping
q small bell with the hand so as to stop
the vibration, when the sound will in
stantly cease; or if bell be placed
under an air pump, as the air is grada-
ally exhausted. the sound will grow
fainter, and finally cease altogether.
All solid bodies conduct sound more
readily than the air, and generally
their conducting power is in proper
tion to their density iron conducting ten
and half times better than air.
Smooth, calm water is very good
conductor, and even the earth conducts
sound much better than the atmos-
phere. Hence, the Indians. by laying
their heads on the ground, will discov-
er the approach of game or the march
of body of men, when others in the
same situation would hear nothing.
But it is its agency in respiration
which renders the study Of the air
most important. In ordinary cases the
lungs are filled with air twenty times
in a minute, from ten to fifteen cubic
inches being inspired each time, ac-
cording to the size of the individual
Thus every full-grown person re-
quires from twenty-five to thirty hogs
heads of air daily, or more than one
hogshead an hour. Not only is this
amount withdrawn from the atmos-
phere, but an equal quantity of an i'm
pure and poisonous gas is returned in
It's stead.
So there is double source of con-
tamination, to say nothing of the large
amount of matter thrown off the skin.
The air thus received into the lungs
is brought into contact with the whole
mass of blood by continuance so won
derful as to merit more particular de-
scription.
If the assertion that "the devout as
tronomer is mad" be true, much more
must an undevout anatomist be liable
to the same accusation; for in nothing
is the wisdom and skill of the Deity
more manifest than in the structure of
the human frame.
The lungs consist of light, porous
substance, penetrated in every part by
minute cells, separated from each other
by membrane of so peculiar struc-
ture that the air readily passes through
it, while the blood is retained.
These cells are so exceedingly mi
mute that cubic inch contains 100000
of them, and the whole lungs S0,0O0,0O0
with superficial surface of 10000
square inches, or nearly 140 square feet,
and all wrapped up in mass not more
than ten inches in length and five or
six inches in diameter.
These cells ore divided into layers,
so arranged that the cells of one layer
are filled with air, while those of the
layer next adjoining are occupied with
blood, the two sets being separated by
membrane so porous that while the
blood is retained, the air can readily
pass through it.
BY this means the whole mass of
blood is brought periodically in con-
tact with the air. The oxygen, amount
ing to one-fifth of the whole, combines
with the carbon of the blood and is ex-
PEELED from the lungs in the form of
carbonic acid, while the nitrogen is re-
turned in pure state.-EUery Other
Saturday..