Strictures on Prof. Dove's Essay. 391 



withstanding its gravity and horizontal momentum, is accomplish- 

 ed without the "influence" of any opposing force ! (par. 122.) 



Dr. Hare seems to think the interposition of the Alleghany 

 Mountains an insurmountable obstacle to the rotation of a storm 

 travelling from the Mississippi to the Atlantic coast, — that the 

 aerial mass would be cut nearly in twain when bestriding that 

 range. — and that more than half of the air in such mass would 

 be below the summits of those mountains. Waiving any errors 

 here, it is allowed on all hands that such mountain elevations, 

 together with the "rugosities and inequalities" of the continen- 

 tal surface, have much influence on the phenomena which are 

 observed in the great whirlwind storms that cross this part of our 

 continent. But it is remarkable, that none of the above consid- 

 erations have prevented Dr. Hare from urging, against Prof. Dove 

 and myself, his own exposition of the reported phenomena of 

 such an overland storm, for the purpose of disproving rotation in 

 tornadoes and hurricanes ! — while he has passed unnoticed, re- 

 ported observations of many storms of the open ocean and its 

 neighboring flat coasts j observations which have fully proved the 

 rotative character of such storms, (par. 124.) 



I have already pointed out Dr. Hare's mistaken exposition of 

 the phenomena recorded by Prof. Loomis of this overland storm ; 

 and the allusion now made by Dr. Hare to " the enormous length 

 of the area of minimum pressure comparatively with its breadth," 

 I conceive to be founded mainly in the error of mistaking the 

 path of " the minimum pressure" for its area at a given moment. 



The observed analogy of the action of small travelling whirl- 

 winds to that of tornadoes and whirlwind storms, to which I had 

 alluded, Dr. Hare labors to set aside, by once more assuming, 

 erroneously, that " momentum" is the force by which the whirl- 



ing body is kept in motion, and then alleging that the great su- 



perficies of a storm having a diameter two hundred times its 

 thickness, must occasion the loss of its momentum. But he 

 seems to forget that the same forces which produce rotation and 

 momentum in a storm must be adequate to their maintainance. 

 Prof. Dove shows that some of these forces are as enduring as 

 the rotation of our planet and the movements and courses of its 

 general winds ; which coincides with my own views. More- 

 over, these constant rotative tendencies in the atmosphere can 

 also be shown by an experiment, from which it will appear that 



