1 40 Strictures on Dove's Essay " On the Law of Storms. " 



110. Page 215, paragraph 3d, Prof, Dove has thus expressed 

 himself: "In considering the progressive advance of the whirl- 

 windy we have not hitherto taken into account the resistance op- 

 posed to the motion of the air by the surface of the earth. This 

 resistance, as Redfield justly remarks, causes the rotating cylin- 

 der to incline forward in the direction of its advance, so that at 

 any station the whirlwind begins in the higher regions of the 

 atmosphere before it is felt at the surface of the earth, where 

 therefore the sinking of the barometer indicates its near approach. 

 The inclined position of the axis causes a continual intermixture 

 of the lower and warmer strata of the air with the upper and 

 colder ones, thereby occasioning heavy falls of rain and propor- 

 tionably violent electric explosions" 



111. In order to appreciate the fallacy of the ideas above pre- 

 sented, it should be recollected that the " rotating cylinder" of 

 air., which is represented as inclining forward, can receive this 

 name only because the portion of the atmosphere of which it is 

 imagined to be formed, is conceived to revolve within that cylin- 

 drical space which must of necessity be occupied by a whirl- 

 wind. To justify this appellation, the gyrating particles must 

 all move in concentric circles about a common axis, and between 

 places parallel to each other and at right angles to that axis. 

 Any other rotative position of the parts must be inconsistent 



with enduring rotation, since it would bring different parts of the 



mass in collision with each other and with the air beyond the 

 sphere of the gyration. It should be recollected, also, that agree- 

 ably to observation, hurricanes have been estimated to extend from 

 one hundred to six hundred miles in breadth. Let us assume the 

 diameter of a whirlwind storm of this kind to be three hundred 

 and sixty miles. Of course the circumference being about three 

 times as great would have three miles for every degree. It fol- 

 lows, that a vertical circle of the diameter of the storm, in a 

 plane coinciding with the axis, would also have three miles for 

 every degree. The altitude of storm-winds is well known not 

 to be above two miles, so that the diameter would be at least 

 one hundred and eighty times as great as the altitude of the 

 axis. Can such a cylindrical mass of air be conceived to incline 

 forward ? One degree of inclination would lift the base in the 

 rear three miles, and two degrees would lift it to the height of 

 six miles, which is never attained by clouds. Besides, as the 



