268 On Dust Whirlwinds and Cyclones. [No. 3. 



Their rotatory actions seem to be continuous above as far as the 

 eye can reach ; and the cloud of dust carried up by them, is observed 

 even at the height of some thousand feet, to possess the gyratory mo- 

 tion, similar to what is seen at the margin of cottony masses of Cumu- 

 lo-Stratus on a clear sky ; which rotatory motion of the cloud, may 

 be due to the very same cause. 



The enormous height to which the dust ascends, may without much 

 Stretch of imagination, satisfactorily account for the occasional fall of I 

 dust, containing microscopic animalcula. 



The dust has doubtless been transported from its original bed by | 

 whirlwinds, sweeping over land once under water, now dry ; carrying i 

 up into the higher regions of the atmosphere, the lighter portions of I 

 the soil, containing these microscopic remains — this seems to offer a 

 simple solution of the enigma. 



But it is a more curious question, what becomes of the enormous 

 amount of dust, which over a broad band of the earth's surface, far i 

 beyond the limits of the ecliptic, is continually being whirled up into I 

 the higher regions of the atmosphere by these whirlwinds. 



The cause of the storm wave, and the storm current, (which as Mr. 

 Piddington observes in his Sailor's Horn Book, page 151,) "are pro* | 

 duced by the forces of the various winds blowing round in the area of I 

 the Cyclone" will be readily understood by the tangent lines marking |t 

 the progression of the sea, and the veering of the winds, PI. 9 and 10. j 



The storm wave corresponding with the side of progression, must, t 

 I should think, generally be impelled to a distance in advance of the 11 

 storm and give, as is said it frequently does, more timely notice of its!: 

 existence and of its track than the Barometer. 



The forces on that side (the side of progression) being of longer! 

 duration in one direction, and. not counteracted by opposing winds andj« 

 waves, as on the looped side of the storm. 



As regards the reality of the spirals, I may remark, that their exist-j 

 ence is not a matter of theory, but of fact, which I have repeatedly 

 verified by observation, and have actually seen them most distinctly; 

 when rendered slightly opaque by fine dust ; and there is no doubt inj 

 my mind, that they are permanent, and of a peculiar nature ; and 

 though I name them Electro-magnetic, my reasons for doing so, is in' 

 consequence of certain electrical phenomena usually attending them] 

 and for want of a better name. 



