98 Dr. Hare's Strictures on Dove's Essay 



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 180 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 density of the air 

 in regions so elevated is only one half of that upon the earth's 

 surface, is it conceivable that a whirlwind could consist of ma- 

 terials so disproportioned in weight? 



116. Can the suggested process of circulation proceed when, 

 in order for the lower stratum to exchange places with the 

 upper, it would have to move nearly half of the circumference 

 of the storm, or more than five hundred miles? 



117. It has been shown that the rotating cylinder of air 

 which constitutes a hurricane, agreeably to the language em- 

 ployed, and the theory espoused by Prof. Dove, may consist- 

 ently with the observed dimensions of storms, have a diameter 

 two hundred times as great as its altitude. The base, of this 

 flat cyUndrical aeriform mass, must be in contact with the ter- 

 restrial surface, and of course in collision with its rugosities 

 and inequalities, while all the rest of the rotating superficies, 

 being contiguous to inert particles of the atmosphere, must in- 

 cessantly share with them any received momentum. Is there 

 any known cause of motion in nature which can impart to a 

 fluid and elastic mass so formed, composed and situated, the 

 various velocities necessary to that simultaneous rotation of 

 the whole which the creation of a whirlwind requires ? In 

 answering this question, it should be recollected that the ve- 

 locities must diminish from the zones of which the gyration is 

 most rapid, towards the axis on one side, towards the circum- 

 ference on the other. 



118. Evidently no transient impulses can produce harmo- 

 nious revolution throughout the mass, unless they act upon 

 every particle so as to impart to each the peculiar velocity 

 which its distance from the axis may require ; and any endu- 

 ring cause operating partially, could only aflect the whole by 

 a gradual process of participation which would cause it to be 

 expanded beyond as well as within any ^'^ rotating cylinder'^ 

 which might be created. 



119. But admitting that in such a mass, under such circum- 

 stances, the gyratory violence of a hurricane could be induced, 

 could this violence be sustained, after the cessation of the ge- 

 nerating forces, merely by the rotatory momentum of an enor- 

 mous aeriform disc, formed, proportioned, supported, and 

 surrounded as the whirlwind above imagined must be, could 

 any such exist? 



