ROTARY ACTION OF STORMS TRACY 



19 



parts of the circle. The breeze from the west extreme inclines to 

 the tangent of the parallel of latitude at its original place of repose, 

 and therefore strikes south of the center into which the impulse 

 it receives would otherwise carry it. The air from the east side 

 also inclines toward the tangent of the parallel of latitude there, 

 which is, obliquely to the north from the radius, and therefore is 

 deflected northwards and strikes north of the center. The breezes 

 from all quarters thus cooperate to produce the result; and all 

 their forces are constant; and act with precision and at great advan- 

 tage to cause and maintain a whirlwind. A diagram presenting 

 the lines of approach of the particles or streams of air, will explain 

 this result. The black lines in fig. 2 show the deviating currents, 

 from the cardinal points alone, when the area affected by the fire 

 is so small as to require no perceptible curve in those lines. 



Upon the same principle, the tornado, the typhoon, and the 

 widespread storm of the Atlantic, if their currents move toward 

 a central spot, must have a rotary character. The circular motion 

 in the outer portions may be slight, but it is stronger near the 

 center. In every such case the incoming air may be regarded as 

 a succession of rings taken off the surrounding atmosphere and 

 moving slowly at first, but swifter as they proceed towards the 

 center. Each such ring is affected by the law of deviation during 

 its passage. The particles are veering from the radii, in its northern 

 quarter westward, in its southern quarter eastward, in its eastern 

 quarter northward, and in its western quarter southward, and 

 hence the ring begins to revolve when far from the center, turns 



