THE BRITISH ISLANDS IK NOVEMBER 1838. 481 



ficxilties involved in the theory, which it requires farther observation to clear up. 

 One of these difficulties regards the velocity of the rotatory movement of the storm, 

 which is found to diminish towards the circumference of the stormy circle. But 

 the reverse might be expected, if the aerial particles belonged to a body which was 

 impelled round a common axis by the influence of some law or force affecting the 

 whole. It is quite obvious, that if there was nothing to interfere with the opera- 

 tion of this force, the rings of wind near the axis of rotation would whirl round in 

 the same time with the most distant rings, and, therefore, with a proportionally 

 smaller velocity. But it is not difficult to see, that there are circumstances which 

 must interfere with the operation of the force above assimied. (1.) The most dis- 

 tant rings are of course retarded by the friction of the atmosphere, through which 

 the storm is rotating and progressing, — as Avell as by the surface of the sea or land 

 over which it is sweeping. The effect of this retardation on the outskirts of tlie 

 storm must be, to a certain extent, propagated to the interior rings. (2.) Farther, 

 it is obvious, that the rotatory movement of parts distant from the axis, will be 

 counteracted by the centrifugal tendency which rotation produces. (3.) Lastly, 

 it is uncertain, whether the aerial column rotates under the influence of a force 

 acting equally on every part of it, or acting only on a central portion. If the lat- 

 ter alternative is made out by observation, aU difficulty will vanish, because, in 

 that case, it is evident that the rotation of the more distant bands may be ac- 

 counted for, simply by their being in contact with the revolving axis. 



Of what the central parts of such storms are composed, and how they are 

 generated, are totally separate questions, which, in the present state of meteoro- 

 logy, may not be readUy answered. But that there is every probability of there 

 being a revolving axis sufficient to put the circumambient air in motion, is clear 

 from the analogous phenomena of water-spouts, or " storm pillars," and " whirl 

 pillars," as the German meteorologists term them. Professor Oersted, in his 

 memoir on these aerial bodies, states, that they are sometimes many hundred, 

 and even occasionally above a thousand, feet in diameter. Such a colunm of air, 

 reaching to the height of several thousand feet (which is the observed height of 

 several water-spouts), circulating with great rapidity, must soon produce an ex- 

 tensive gyratory movement in the atmosphere to a gi-eat distance, and thus ex- 

 hibit most of the phenomena of Redpath's stormy circles. The analogy between 

 water-spouts and storms of wind, is made stiU more obvious, by the fact men- 

 tioned by Professor Oersted, that, in Europe, these water-spouts have been ge- 

 nerally observed to move in a du'ection from SW. to NE., being very nearly' 

 the direction of the best traced European and American storms. 



It has been thought, that the formation of an aerial axis of gyi'ation may be 

 easily accounted for, b}^ the mutual action of two ciurents of air, flowing in oppo- 

 site and parallel or nearty parallel directions. These currents would, of course, 

 form an eddy, which, in the form of a rotating body, will advance in the dire< - 



