Western Reserve chronicle. [volume] (Warren, Ohio) 1855-1921, 1870-12-21
LION 60 Health for peeember.I
The barometer. or wsather.GIass.

From Good Health for December.i
The Barometer, or Weather Glass.
Next to the question, "What is the
time ?r is the morning household in
duiry as to "What will the weather
be?D A barometer, as well as a clock
or watch, is usually to be found in ev-
cry house, but the reason for its
weather-indieating oscillations is too
frequently passed over as practically
unimpOrtant, or regarded as lone Of
those things which no fellow can COM
prehend. - The instrument itself is
exceedingly simple in construction,
and the principle upon which it acts is
readily explained.
for determining the present or forth
coming state Of the weather, the fol-
lowing instruments are indispensable,
viz: a barometer, a thermometer, and
an hydrOmeter, in connection with the
observed direction of weathercOck.
The BdrOmeter.-For two thousand
years the phenomena on which the
action of the weather-glass is depend
ent NOW referred to the pressure of
the air) were explained by the dogma
Of the ancient philosOphers-that ma
tltrc dbhOrS q UdcuuHl." 1t was no.
ticed that space was always filed with
some material substance, and that the
moment a solid body was removed, sir
or water always rushed in TO fill the
space thus deserted. Hence it was
concluded that it was universal law
of Nature that space could not exist
unoccupied by matter, and the above
phrase was a figurative expression of
this idea.
Thus, when the piston Of a common
pump was drawn up, the consequent
rise Of the water was explained by de-
elaring that, as according to the nature
of things a vacuum could not exist,
the water Of necessity rushed into the
space the piston had previously Occu-
pied. In the middle Of the seven
teenth century philosophers discover
ed q limit to Natures adherence OF a
vacuum. Some Florentine engineers,
employed in sinking a pump to an
unusual depth, found they could not
raise water in the tube higher than
ten metres, or thirty-twO feet. So re-
markable appeared this limit to their
skill, that they consulted the great
philosopher GalileO; but though he
had taught that air has weight, he
failed to perceive the proper eXplana-
ton why the water could not be raised
higher than thirty-two feet, and is
said to have replied, that Mature did
not abhOr vacuum ADORE ten metres. "
This engineering failure led to q
most important physical discovery
Torricelli, a pupil Of Galileo, pursued
the inquiry, and reasoned that the
force, whatever it might be, which
would sustain a column of water ten
metres high, in a cylindrical tube,
must be equivalent to the weight of
the mass Of water sustained; conse-
quently, il another liquid, heavier
than water, were employed, the same
force could only sustain q column of
prOportionally less height.
The liquid metal, mercury, being
49, times heavier than water, Tori
celli argued that the force that sus-
tanned a column OF water ten metres
high could only sustain a column OF
13{ times lower, or about 76
high. To prove this, he
made the following experiment, one
which has ever remained memorable
in the history of science. TOrricelh
took a glass tube, about 81 inches long,
open at one end and closed at the
other; this he filed with pure mer-
closed the open end
with his thumb-and inYerting the
tube, plunged the open end into ba-
sin Of mercury. On removing his
thumb, the mercury, instead Of re-
manning in the tube, fell, as he ex-
pected, and after a few oscillations
came to rest at a height Of about T6
or 80 inches above the
level Of the mercury, in the basin.
The correctness Of his argument be-
ing thus verified, he further reasoned,
that the weight Of a column Of air Of
the height of our atmosphere was just
sufficient to eOunterbalance or support
a column of water about 80 feet in
height, or a column of mercury about
30 inches in height.
This experiment, and the resulting
doctrine, caused a great sensation
among European SGUGHtS, and las is
usually the case when teachers have
to be sent to school again to unlearn
what they have taught opposition
The celebrated Blaise Pascal, hOwev-
er, recognized the force Of TOrricelli's
and devised a crucial ex-
pertinent. IF said he) it be really
the weight of the atmosphere, under
which we live, that supports the col
umn of mercury in TOrrieellis tube,
we shall find-by transporting this
tube upwards in the atmosphere-that
haNr
more and more of the air, and has
less and less ab0Ye it,
here will be a less column sustained
in the tube; inasmuch as the weight
)f the air above the tube, which is de-
,lared by Torricelli to be the force
which sustains it, will be diminished
Dy the increased elevation Of the
.ube." This argument Pascal verified
ly first sending TOrricelli's tube to
he top Of q church steeple, and up
wards to the top OF the high mJuntain
If Puy de Dome. N the first in
tance, he found only a slight fall In
he height Of the mercury, but in the /.
econd, the difference between the I
height Of the column on the plain and I
m the mountain top amounted to I
learly eight centimetres, or three .
inches. This experiment put an end .
o further controversy on the subject, |
nd the dogma Of Natures adherence I
# a vacuum had to give place to an 4
philosophical principle.
If we repeat tTOrricelli's experiment,
We shall notice that, on the mercury
which completely fills the tube) COM
ng to rest, q vacant space is left in
he upper part Of the tube. This is a
aeuum, the most perfect one it is
.Ossible to attain, and which is known
.nder the term Of the "Torrieelli
If we bring a TOrricelli
ube under the influence Of an ex-
syringe, on working the
Jump we shall find that with each
pward stroke Of the piston, as the
ressure on the surface OF the mercury
D the cistern decreases, there Is a cor
fall in the column of mer-
ury, and rise in the level Of the mer-
ury in the basin, as the rarefied air
an no longer support 80 inches Of
nat metal. II, on the other hand, we
ring q TOrricelli tube under the in
uence Of a eondensing syringe, on
lcreasing the external pressure on
ne surface Of the mercury in the els
ern, the column of mercury rises,
nd the mercury in the basin falls.
As a column Of mercury so inches
iUh and I inch s11rerfirial in section / 1