1851.] Report on the Dust Whirlwinds. 367 



calculated to enlighten us, either as regards the circular motion 

 of the wind or the progressive motion of the meteor, it nevertheless 

 is interesting as exhibiting one phenomenon which will be found to 

 be of not unfrequent occurence, viz. 



a. Heavy falls of rain in this part of India are sometimes pre- 

 ceeded by a loaded condition of the atmosphere with impalpable 

 dust which could not be accounted for by the amount or force of 

 wind blowing at the time. 



7. — 13th March, 1853. 'The sky still continued dark and cloudy. 

 Towards evening very dark clouds arose in the west and W. by N. 

 Much lightning, both sheet and forked, was evident. Towards 8 

 o'clock the near approach of thunder was audible, but the storm was 

 seen to pass by the station to the N. and E. A slight shower of 

 rain fell. 



The above description is also imperfect, but it tends to teach us 

 that, 



a. Some storms in this country are so partial and well denned 

 in extent, as to render it a matter of no difficulty to trace their 

 course. 



8.-25^ March, 1853. The following description of the 8th and 

 9th, storm observed and registered is taken nearly verbatim from 

 notes written at the time. 



In reference to No. 8, it is noted that " the day was cloudy, 

 prevailing clouds strati and cumuli. Hot and sultry, — a very gentle 

 breeze was blowing. About 5 p. m. a diffused haze of dust to the 

 N. W. and N. indicated wind in that direction, and shortly after- 

 wards, a slight increase of wind took place from W. by N. 



It only lasted a few minutes, and the dust storm such as it was 

 passed N. of the cantonments and speedily broke up. 



9. — 26th March, 1853. Hot all day, clear and sunshine, a few 

 cumuli and cirri. About 5 p. m. sky in N. W. became dark, and 

 a few columns of dust were seen in different parts of the darkness. 

 The wind at the time was N. W. and W. by N. but not very 

 strong. The body of the storm like the previous one passed N. of 

 cantonments. 



Note. — Although there are many reasons for presuming that the 

 two last small storms were circular, in which case the motion of 



3 c 2 



