WIND S. 



405 



initiations can be carried off. The atmosphere over the sea has 

 become, as it were, a vast reservoir or well-charged battery. The 

 development of it in many places gives evidence of its existence in 

 vast quantities, and is looked upon as a precursor of these storms. 

 The temperature of the sea has reached its maximum, and the greatest 

 heat of the atmosphere coincides with it, and prevails throughout the 

 route these storms take. The appearances which we have given, as 

 immediately preceding these tempests, also show very clearly powerful 

 electrical action. On their development, a discharge, or successive 

 discharges, either disruptive or convective, take place, and a great 

 repulsion of the atmosphere, by electricity, causes the displacement 

 of the atmosphere from the surface of the earth to take place, baring- 

 it or exposing its surface, creating a large rarefied area, into which 

 the surrounding air rushes with great force, which, coming in contact 

 with the earth's surface, moving from west to east, receives the im- 

 pulse of its rotary motion, producing a horizontal whirl or volute 

 from right to left in north, and from left to right in south latitude. 

 This whirl continues until friction overcomes its velocity, when it dies 

 away into calm. This is the local effect of the discharge. 



The storm continues to advance along the line or route of highest 

 temperature, coinciding with the line of minimum pressure, and pro- 

 gresses in the direction I have named as retrograde on our coast, from 

 the southwest to the northeast, first having originated, as was observed 

 by our celebrated countryman, Franklin, at the south. 



As the electric fluid accumulates along the line of heat, it makes 

 successive discharges, either disruptive or convective, producing the 

 same effect as in the first instance, and the same results, more or less 

 violent, according to the intensity of the action of the fluid. Thus 

 the route of the storm follows the line of greatest heat. At each 

 point of accumulation and discharge, the whirls form and continue 

 until their action is exhausted by friction; or, when the equilibrium 

 of temperature is restored, they cease. 



Other causes, no doubt, tend to increase the effects which take 

 place, — the expansion of vapor, its condensation, and the evolvement 

 of large quantities of heat, and great precipitation, which always ac- 

 company these hurricanes. 



The falling of the barometer at the central line is the result of its 

 being the line of maximum heat ; the expansion of the column and 

 the upward tendency of the air may increase the effect. Too much 

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