12 Eleventh Memoir on the Law of Storms in India. [[No. 157. 



In the Northern Hemisphere. 



We have principally to remark here on what we may call the 

 u generation of separate storms" at short distances from each other so 

 analogous to what certainly occurred in the Calcutta storm of June 

 J 842, though we might there suppose it to have been occasioned by 

 the influences of the land, as hills, valleys, &c, but it would now ap- 

 pear that the state of the atmosphere which induces one rotatory 

 storm often disposes, or gives rise to, others, just as after certain states 

 of summer weather in Europe, we hear of a succession of thunder 

 storms all over a large tract of country. 



Thus we find that when the Fyzulbarry's storm (a true rotatory 

 one) had travelled up from the S. Eastward two or three days, 27th 

 or 28th to the 30th, another storm appears to have commenced at four 

 degrees' distance with the Candahar, which we trace accurately enough 

 through two days as travelling to the W. S. W. and if our conclu- 

 sions be correct as to the Niagara and Mary Imrie, that the Fyzul- 

 barry's storm when approaching this of the Candahar's, curved away 

 to the W. b. S. This looks strange enough, but whatever are the 

 causes of them, the dust whirlwinds on the plains of India, of which 

 I have seen as many as four or five at a time, certainly do influence 

 (repel) and alter each others tracks. We do not know if these arise from 

 the same cause, but it is the only analogous fact that I am acquaint- 

 ed with,* and the scientific reader will judge from the data set down 

 whether he thinks they are sufficient to entitle us to lay down the 

 tracks which I have here given. There is I think no doubt of the 

 storms being altogether separate ones. 



It is remarkable that all these forces and storms seem to have been 

 blended so as to produce one about Palks' Passage, evidently travelling 

 to the Westward also, or rather generated like the other in advance 

 of those raging in the bay, for we find that the Ceylon storms all be- 

 gan on the 1st, when the nearest centre, that of the Candahar's storm 

 was at least at three degrees of distance ; and it could not be part of 

 this, for the Vernon's position limits it to the N. W. within a much 

 more circumscribed circle, and I am therefore inclined to believe that 

 at sea as on shore, independent vortexes arise like independent thunder 

 storms. 



Postscript. 

 In the preliminary notice to this Memoir, I announced that I had ob- 

 tained from the Mauritius the detail of what I may call a beautiful expe- 



* " It is possible that one storm may deflect another says Col. Keid," p. 433, 2nd 

 Edition of his work. 



