Smithsonian miscellaneous collections . f the currents from the easterly and westerly ROTARY ACTION OF STORMS TRACY 19 parts of the circle. The breeze from the west extreme inclines tothe tangent of the parallel of latitude at its original place of repose,and therefore strikes south of the center into which the impulseit receives would otherwise carry it. The air from the east sidealso inclines toward the tangent of the parallel of latitude there,which is, obliquely to the north from the radius, and therefore isdeflected northwards and strikes north of the center. The breezesfrom all quarters
Smithsonian miscellaneous collections . f the currents from the easterly and westerly ROTARY ACTION OF STORMS TRACY 19 parts of the circle. The breeze from the west extreme inclines tothe tangent of the parallel of latitude at its original place of repose,and therefore strikes south of the center into which the impulseit receives would otherwise carry it. The air from the east sidealso inclines toward the tangent of the parallel of latitude there,which is, obliquely to the north from the radius, and therefore isdeflected northwards and strikes north of the center. The breezesfrom all quarters thus cooperate to produce the result; and alltheir forces are constant; and act with precision and at great advan-tage to cause and maintain a whirlwind. A diagram presentingthe lines of approach of the particles or streams of air, will explainthis result. The black lines in fig. 2 show the deviating currents,from the cardinal points alone, when the area affected by the fireis so small as to require no perceptible curve in those Upon the same principle, the tornado, the typhoon, and thewidespread storm of the Atlantic, if their currents move towarda central spot, must have a rotary character. The circular motionin the outer portions may be slight, but it is stronger near thecenter. In every such case the incoming air may be regarded asa succession of rings taken off the surrounding atmosphere andmoving slowly at first, but swifter as they proceed towards thecenter. Each such ring is affected by the law of deviation duringits passage. The particles are veering from the radii, in its northernquarter westward, in its southern quarter eastward, in its easternquarter northward, and in its western quarter southward, andhence the ring begins to revolve when far from the center, turns 20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 51 more and more as it draws near it, and finally as it gathers aboutthe central spot all its forces are resolved into a simple after ring
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Keywords: ., bookauthorsm, bookcentury1800, bookdecade1860, booksubjectscience
