1854.] Report on the Dust Whirlwinds. 371 



were visible in the latter direction, moving in opposite directions, 

 and the lower border of that forming the arch was illuminated by the 

 sunshine. Thunder was loud and increasing, lightning became 

 vivid, especially in W. : streaks, as if of rain falling were observed 

 in various directions extending downwards from the border of the 

 arch just described. Soon after this, the wind struck our honse at 

 W. by N. a very severe storm then came on, and hail stones of 

 considerable size fell thickly. The wind soon veered to W. then to 

 W. by S. and in less than half an hour the sun again shone out, 

 the body of the storm was visible progressing N. E. and contracting 

 in its diameter. A splendid rainbow appeared at its nearest border # 

 (Plate XVII.) 



The Chart I. 1853, is intended to represent the progress of this 

 storm. The wind seemed to be from L. to R. the diameter probably 

 8 or 10 miles, and the onward movement of the cyclone very rapid 

 although the want of apparatus rendered it difficult to say at what 

 actual rate it progressed, we may however presume that, its diameter 

 being 10 miles, and the period of its continuance half an hour, it 

 must have moved onwards at a rate equal to 20 miles per hour. 



It may be noted that some of the hail stones that fell during the 

 above storm weighed one rupee. The evening, after the cyclone 

 had passed over, was clear, the atmosphere bracing and cool. On 

 the horizon between S. and E. much lightning was visible, the 

 flashes showing towering masses of thunder cloud in that direction, 

 but no thunder was audible. 



It may be further observed, that the temperature was moderated 

 for several days after the occurrence of the above storm. 



The following are some of the points of interest that the cyclone 

 just described teach. 



a. That the circular motion of the air was L. to E. 



h. That the diameter of the cyclone underwent modification as 

 it progressed. 



c. That the onward course or track of the storm was more or 

 less eliptical, as indicated by the chart. 



14. — 20^7* April, 1853. The early part of the day was cloudy, 

 the sky much obscured by various modifications of strati. Shortly 

 after 4 p. m. the appearance of a dense mass of thunder cloud in 



