Lamoille newsdealer. [volume] (Hyde Park, Vt.) 1860-1877, 1861-04-05
THE BAROMETER AND ITS USES.


1.-THE following article, which we copy
from the N. b. Farmer of the Sth of
Sept. last, cannot fail to be interesting to
every business man, and especially every /
farmer. 1t will be seen that the instru-
ment spoken of is the same as that adver-
tised by G. Whiting, Of johnson j
The word Barometer is derived from
two Greek words, signifying weight and
measure. The instrument, theforc, is to
measure aoeight, as applied to the atmos-
phere, or is in other words, to determine
the pressure of the atmosphere. 1t is well
known that the weight Of column of air
one inch square, and of the height of the
atmosphere above the earth, is equal to
about Is lbs. This column will then
sustain column Of water, mercury or
any other fluid Of similar size, and high
enough to make it equal in weight. The
column of water which can thus be sus-
tained is 80 feet in height, the column of
mercury about 20 inches. Galileo COM
menced, near the close of his life, exper-
iments to ascertain why column of wa
ter could be raised in vacuum only to
the height of 80 feet Without COM
pleting these experiments he died, and
left his pupil, Torriceli, to pursue the
investigation. He used mercury; filling
a tube, closed at one end, with the fluid,
he placed his finger over the other end,
which he then immersed in a basin of mer-
curry, holding the tube upright. Upon
removing his finger, the mercury in the
tube sunk and finally rested at a height of
2S inches above the level of that in the
basin. Repeated experiments resulted in
the same way, and thus was discovered a
principle in natural law which is as un-
changeaDle. as the nature of the Creator.
The Barometer thus being invented, it
was not long before the changes of the
atmosphere were discovered to affect it.
Pascal, a French philosopher, also inferred,
and established the truth of his inference
by experiment, that the Barometer would
indicate lessened pressure of the atmos-
phere by ascending with it above the or
dinary level of the earth s surface. Those
experiments were conducted in the years
1912 to 1913. Numerous attempts have
been made to modify the form of the ba-
rometer, but those now most approved are
essentially the same as Torricelli's, q
straight inverted tube, about 80 inches IL
length, and mercury as the measuring
liquid. Some have been made where nc
liquid was used, but the weight Of the
atmosphere was determined by its pres
sure upon the sides of metal box from
which the air had been exhausted. Tit
mercurial barometers are, however, thu
standard, and much preferred by scientific
men. .....,e. ...... =.
1t is obvious that the weight of tn,
atmosphere is not always the same. Th'
presence Of moisture, the variations 0
heat and cold, and the force of the winds
all operate to make the weight of the at
mosphere at any point, an almost con
stantly changing quantity. Observation
for now more than two hundred year
have enabled us to judge with much ac
curacy, by these changes in the weigh
of the atmosphere as indicated by tn
barometer, of approaching changes in tn
weather. 1t has been found that almos
invariably certain atmospheric change
precede change of the weather from we
to dry, or from dry to wet, and that tn
barometer never indicates SO high an al
titude during q storm as during DIR.
: weather. These observations have estat
s lished set of rules for judging Of az
9 preaching changes of weather, which W
' shall give at the close Of this article io
The index affixed to some barometer
: marking upon circular disc the heigh
: Of the mercury, with the alleged CORE
! spending condition of the atmosphere,
!, of no value, and is calculated to misleat
$ In fact the altitude Of the barometer {
2 any given time is not alone 9 guide to y tf
) weather. which may follow, but the trs
guide is-whether the height indicated
more or less than that indicated sho
= time previously whether the mercury
I. declining. or rising, at the trme OF obser'