Nashville union and American. [volume] (Nashville, Tenn.) 1868-1875, 1871-08-12

ZION winch was ditSINdu5 OSlAOnSslayeO
by Ferrel and Dove. Great interest has
been awakened in, and increased attention
given TO the study of meteorology by the
labors of these distinguished scientists.
Mr.. w. G. Redfeld, who, in addition TO
the establishment of the fact that storms
have gyrstory motion, was close stu
dent CT all stmospherical phenomens,
first applied the telegraph to the signal
ing of storms. Prof. Henry, of the
Smithsonian Institute, urged upon Con-
gress the policy of putting the suggestion
Of Mr.. Redfield into execution, SO as 10
have coming storms announced and there
by be able TO protect shipping from their
destructive effects. He obtained liberal
appropriation, and ont of this has grown
the Weather Bureau.
This Signsl or Weather Bureau, by
combination of telegraphic currents, takes
spontaneously the observations Of the
weather at seventy select points in tie
United States, and these observations are
published in all the leading papers in the
country. There are taken the height of
the barometer and thermometer, the d.
rection of the wind and its velocity, the
relative humidity of the air and the state
of the weather at each of these stations.
From these data a map is constructed and
the probabilities Of the weather for the
next twenty -four hours arc predicted
The experience during the past year shows
lat these conjectures, based upon immu
table lava, await but the developments of
time and larger accumulation of facts 10
make them in all essential particulars es
accurate rs the foretelling of the rising
and setting Of the sun, the cccultstions of
Venus. or the time of an eclipse of the
sun or moon.
In order that our readers may under
stand the philosophy and principles upon
which these coDjectures are founded, we
premise that in all counties during GER
tain seasons there are general winds, de-
pendant upon The rotary motion of the
earth, and upon uniform and fixed mete
geological laws, varying with regularity
as the seasons change. Tnese arc TO be
carefully distinguished from local winds,
which result from the local pressure Of
the atmosphere, and are influenced by
the elevation or depression of the LEGALITY,
the quantity of humidity in the atm)5-
phere, by local distractions, and several
other minor causes not necessary here to
mention. Or to make the matter palmer,
we are to look upon the general winds as
constant forces acting regularly, while
the local winds are variable and incon-
slant, sometimes acting in conjunction
with, and sometimes in opposition to, the
REGULAR aerial currents. Now the regular
winds, as modified by their local currents,
will give the probable course of the wind
st any given time. To illustrate
the methods used: The normal
height of the barometer on the Atlantic
coast is 5000 inches. If, then, Cbser-
vations are taken at two points and
the pressure is fonnd to be 90. 95 and
SO.O5, then the presumption is that mid
way between these points the barometer
stands at 5000. Now, By connecting al
these points of equal pressure, there may
be seen the narrow band over which the
barometric pressure is uniform. After
having drawn The normal line of 5000
inches, similar lines may be drawn SHOW
ing the line OF equal pressure
when the barometer stands at 1890,
90. so, etc. Passing TO the other side of
the normal line, the points where the ba
rometer stands at 80 10, 1920, etc, may
be united, and Sd on for all the points OF
equal pressures. These lines are called
isObarometric lines. Sometimes they in
close g central area, in which the pressur'
grows less and less to the centre. Tht
isobarometric lines then drawn form con
centric circles. Now, within areas O
, this character, where the atmcs
{ phere must, in accordance will
: known mechanical laws, be pushing from
, this regions of higher 10 those OF lowe
pressure, occur cyclones, tOrnSdoes ant
! thunder storms. II, on the other hand
/ the centre is found 10 be OF highest pres
sure, the wind, III obedience to the SAINT
law of mechanics, VIII blow outwardly
J or from the centre, detected, of course
z nv those general laws arising from tn
: revelation of the earth about lis axis
o. which slways tuln il tn he right as
J moves forward. When there are no we
T. marked central areas, the winds, by uni
2 ting with the lines OF equal pressure, ia
dictate some area beyond thu limits Of OF
s servation. 10 the summer, for instance
4 .be south aud southeast winds iDdicat
E the low pressure that prevails in the MI
G eonri valley. When The pressure over
D large area is uniform, then minor lGcs
) influences sometimes affec. the winds
, such as Temperature and humidity.
: Now if we add to the barOmeteTical q
= seryaions the temperature of particuls
% mace with the isothermal lines and ia
2 isobsrometic linen, shown on mar
Il Giving in che connected view the whol
+ state Of the atmosphere, with the loc'
?, and general influences, any one ma
d readily infer what will be the pIobabl
4 sialG OF the weather for the ensuing twer
IF ty-four hours, especially if added 10 TIL
b, is another element, viz: the amount c
% humidity that prevails, and the kinds ar
le changes of the clouds. These lsst indi
2. cate the relative temperature, moistur
81 and pressure, existing in the upper ali
90 The ascent of warm air makes cunluLou
a clouds. They disappear when not fed b
III these currents. Tie cirrus clouds
which are known by their hairy, brusi