372 Report on the Bust Whirlwinds. [No. 4. 



N. E. indicated the existence of a storm in that direction. At 4, 

 30 p. M. the wind struck with considerable violence at N. as noted 

 in Table II. 1853. At 5, 30, it was at N. E. and before 6, the dust 

 had cleared away, but the outline of the storm could be seen extend- 

 ing a little above the horizon at S. "W. or S. W. by S. 



About 6 1 p. M. a similar storm appreached from the same direc- 

 tion, but was very small and of inconsiderable violence ; only lasting 

 a few minutes, when it appeared to break up. At the same time, 

 two other partial clouds of dust were observed, one on either side 

 of, but at a little distance from this, but they also soon broke up. 



Although in gusts such as have just been described, it is a matter 

 of difficulty to say on all occasions in what direction the wind 

 moves, whether circular, or in direct lines, — we may nevertheless 

 presume that in the one noted in the chart II. 1853, (Plate XVIII.) 



a. The motion of the wind was from E.. to L. or that which 

 authors describe all storms in the northern hemisphere to have, — we 

 moreover learn that 



b. Cyclones at times may be seen to break up or expend them- 

 selves. 



15. — 27th April, 1853. The whole forenoon was hazy, the atmo- 

 sphere so much obscured by dust as to render it impossible to see 

 to a greater distance than 100 to 150 yards. About 1 p. M. the 

 wind became very strong from S. and between that hour and 4 p. m. 

 gradually veered round by W. to N. at which latter point it 

 ceased about 7, gradually varying, however, a few points E. and W. 

 of North. 



Erom the very obscured state of the sky, it was utterly impossible 

 to say positively from what direction the body of the storm came. 

 It appears tolerably evident that it was circular, and on this suppo- 

 sition the chart III. 1853, (Plate XIX.) has been constructed, the 

 course of the wind and cyclone track being noted in the diagram 

 according to both suppositions, namely, 1st that its motion was 

 from E-. to L. and 2nd that it was from L. to H. 



The above storm must therefore be taken as a very striking exam- 

 ple of the fact 



a. That it is at times impossible for a single observer to say at 

 the time what is the circular course of wind in a cyclone, and there- 

 fore, as a matter of course, 



