|r6 On the prevailing Storms of the Atlantic Coast. 



solid. It is most obvious, however, that all fluid masses are in their 

 gyrations subject to a different law, as is exemplified in the foregoing 

 experiment ; and this difference, or departure, from the law of solids 

 is doubtless greater in aeriform fluids than in those of a denser 

 character. 



The whole experiment serves to demonstrate, that such an active 

 gyration as we have ascribed to storms, and have proved, as we 

 deem, to appertain to some, at least, of the more violent class, must 

 necessarily expand and spread out, by its centrifugal action, the stra- 

 tum of atmosphere subject to its influence, and which must conse- 

 quently become flattened, or depressed, by this lateral movement, 

 particularly towards the vortex or center of the storm, lessening 

 thereby the weight of the incumbent fluid, and producing a conse- 

 quent fall of the mercury in the barometrical tube. This effect 

 must increase till the gravity of the circumjacent atmosphere, super- 

 added to that of the storm itself, shall, by its counteracting effect, 

 have produced an equilibrium in the two forces. Should there be 

 no overlaying current, in the higher regions, moving in a direction, 

 different from that which contains the storm, as in case of violent 

 storms of great extent there probably is not, the rotative effect may, 

 in these latitudes, be extended into the region of perpetual congela- 

 tion, till the medium becomes too rare to receive its influence. But, 

 wherever may be the limit of this gyration, its effect must be to de- 

 press the cold stratum of the upper atmosphere, particularly towards 

 the more central portions of the storm, and, by thus bringing it in 

 contact with the humid stratum of the surface, to produce a perma- 

 nent and continuous stratum of clouds, together with a copious supply 

 of rain, or a deposition of congelated vapor, according to the state 

 of temperature prevaihng in the lower region. 



If the view which has before been taken of the forward inclination 

 of the axis and advancing margin of the storm be well founded, it 

 will result, that on its approach, the barometer will usually be affect- 

 ed previously to any sensible indications of its proximity, especially 

 if the storm be a violent one, and that the sinking of the mercury 

 will continue till the nearest approach of the center of the storm, as 

 existing in the higher parts of the atmosphere. It will also ordinari- 

 ly happen that, previous to the arrival or passage of the center of 

 rotation, as exhibited at the surface, the mercury will commence 

 rising, and continue its ascent during the approach and prevalence of 



