New-York tribune., 1874-04-25
ON THE LAWS OF CYCLONES.

BY PROF. WILLIAM FERREL OF THE COAST SURVEY.
There were at one time two rival theories
with motions OF the atmosphere In cyclones
According to Espys theory, called the radal theory,
the atmosphere flowed In from all sides toward the
center in the direction of the radius and ascended in
the middle OF the cyclone and flowed out above. Ac-
cordng to Reded, Reid aud Others the motion OF the
atmosphere above and below was that OF a circular
yration around the center OF the cyclone. and there
was no motion either 10 or from the center.
In the year 1859 IN paper published in Runkles
Mathematical Monthly Prof. Ferrel first demon
strated the effect oi the earths rotation upon
any body moving upon its surface. which was TO
cover detecting force at right angles to the di-
hemisphere but to the left m the southern II was also
shown that the effect OF this DETECTING force upon air
tending from all sides toward center, was to cause 1t
also to gyrate around this center and that
Consequently Espy's theory could not be true.
the DETECTING force arising the earhs
in the direction OF the radius from the center, and
depression and low barometer IN the center
but force to overcome the Resistance TO the
cyraon and hence the atmosphere IS soon brought to
OF rest There must, therefore, IN ali cases be
some motion below, toward the center OF the
upon the earth's rotation--arsing from this COM
ponent OF the motion. may overcome the resistance
e the Tss1an ef Of the roS s1d
the motion toward the center gives motion. the
bar or line of equal baTometric pressure. Here Prof.
Ferre circle the blackboard showing the line
sstances the greater this angle must be- and hence
since resistance as the square to the velocity all other
atmosphere IN the cyclone the greater msi be TINS an
ge rhe angel shown on the blackboard as formed
by a tangent TO the circular sobar)
on the open where the amount OF resistance Ia
small especially when the yelocties are not very great
cuar Redhelds theory requires In violent
land where the resstances are very great TINS ange
do not differ much from those OF the radl and hence
there IS an approximation to Espys theory As Espy
took his observations mostly from tornadoes on land
and Redfeld took his mostly from large cyclones
at sea, each one had observations which, with little
Gently no considerable number OF observations have
discussed TO determine from observation the truth
OF the preceding Jaws adduced from theory. The Rev.
Clement Ley recently. from great number OF
tons made by the signal service OF England, France
average for the angie between the, direction
Of motion and the isobar for all the stations
theoretical law above. BY taking the average,
also for five stations the coast, where the resist
he found the value Of This angle only 1870, while for
ve stations entirely inland, where the resisances
greater the average gave 29 for the value OF this
angle This veres another part of the theory above,
namely taat the greater the the e, more must
and consequently the more must the gyratons deyiate
Beside the ordinary cyclone which have treated,
there Is also what 70 called an anticyclone In this
is in the center and hence the air descsnds
there and flows out all sides below. aud in from all
sides above, and hence the motions a vertical plane
For this IL generally supposed that the hor
but this IL mistake. The gyratons in both cyclones
are precisely the ana such have been given for
the ordinary cyclone Anticyclones always station
AIRY; having their ceners In the interior OF continent
or larger island where the atmosphere In Winter
colder and consequently heavier than the
rounding and hence IL descends Ia the middle and
flows out at all sides below. and the DETECTING force
already explained gives rise To stationary cyclone.
Each hemisphere OF the earth contains grand anti
cyclone, with the cold Pole In the center aud the
half OF the torrd for Its external part,
and In these antcycones we have ayerication OF what
"a stated above the northern hemisphere the
gyrations nearest the Pole from right to LETT giving
the eastward current In the middle and higher
latitudes, while toward the external border at the
equator the gyraOns the contrary way giving rise
10 the general westward motion OF the air In the torrd
zone In this case also as ordinary cyclones the
baroeter stands the highest at the dividing parallel Of
latitude OF about 80 degrees which separates the two
| systems VI gyrations OK winds.