1854.] Report on the Bust Whirlwinds. 373 



h. Equally impossible to detect the cyclone track. 

 16. — \Otk and llth May, 1853. Since the occurrence of the last 

 storm described, the temperature continued to range in an open 

 verandah to 104° F. and in the house to 84° and 87° F. the sky 

 being clear : on the 8th some cirri were observable in the W. shortly 

 after sunset, and on the 9th in E. at sunrise. These continued to 

 increase (as they always do in this station for some days before a 

 storm of wind or rain). 



On the 10th occasional pillars of dust were seen in various direc- 

 tions, but although extending high and perpendicular, they had no 

 circular motion, their only movement being directly onwards. They 

 first became evident about 4, 30 p. m. and continued till sunset ; the 

 heat of the air being very oppressive, no breeze blowing at the 

 time. The evening was intensely dark, especially towards the N". ; 

 and during the night high winds continued, but no observations 

 were made. 



During the morning and forenoon of the llth, the same high 

 wind continued from N. E. with occasional drops of rain. Towards 

 the afternoon, the wind increased until at sunset it blew a very 

 stiff breeze, bringing with it clouds of dust, and continuing steady 

 N. E. About 7, 30 p. M sheet lightning in great quantity appeared 

 S. W. and N. W. and about 9 o'clock rain began to fall in torrents 

 and so continued, the wind all the while not lulling until 3 a. m. 

 of 12th, when the weather cleared up. 



In the notes of the above storm, taken at the time, it is stated 

 that " I could not see any thing in the above to induce me to sup* 

 pose that it was other than a parallel wind fromBT. E.," and it ap- 

 pears really to have been 



a. A rectiliniar storm. 

 It also teaches us that, 



b. The columns of dust that precede storms may under certain 

 circumstances have no circular movement. 



c. They may occur while there is no perceptible movement of 

 the air even in their mere vicinity. 



d. Storms during the hot months are often preceded for several 

 days by the appearance of strati in the West at sunset. 



Note, — It appears that during the whole of the 12th, occasional 



3 D 



