THE STORMS OF SOUTH AFRICA. 

 By a. G. Howard. 



[Read 4th May, 1887.] 



INTRODUCTION. 



The subject which I am going to deal with to-night, is one which 

 has exercised the minds of meteorologists ever since meteorology has 

 been in existence ; that is to account for the various phenomena 

 relative to storms. 



Ever since the invention of the Barometer, theories have been 

 advanced on the subject of its oscillations. 



First, it was thought that the wind was the cause and not the 

 effect. But no reason was shewn why the wind blowing from one 

 direction should cause the mercury to rise, and from another direction 

 cause it to fall. 



A great light was thrown upon the question when simultaneous 

 observations were plotted down, and lines of equal pressure, called 

 isobars, drawn. It was then discovered that these isobars invariably 

 resolved themselves into a form approaching to that of a circle. 



The next discovery made was that the wind always blew round the 

 circle with the lowest pressure to the left, thus blowing from opposite 

 directions when the centre was an area of low or of high pressure. 



This was the Cyclonic Theory. 



According to this theory, every storm consists of a circular-shaped 

 area of low pressure, round which the wind blew in a direction against 

 watch hands in the Northern Hemisphere, and with watch hands in 

 the Southern one. But here the whole truth had not been arrived at, 

 and many accidents were caused by a sudden chopping of wind, quite 

 at variance with the cyclonic theory. 



Now although the greater number of storms are not entirely 



cyclonic, yet, as a matter of fact, some storms are true cyclones, and 



are experienced in the West and East Indies, as well as often being 



found, of small extent, rollijg along between two opposing 



.anti-cyclones. 



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