3i 



lcokingdown on the North or South pole respectively. Being 

 opposite .in the two hemispheres, the effect of the earth's 

 rotation on the winds is null at the equator, and consequently 

 cyclones are not formed there, nor do they cross it. 



Cyclones are formed along the line where the northern 

 and southern trade-winds meet ; but for the reason stated 

 above, they are formed only where that meeting takes place 

 at some distance from the equator. For this reason they do 

 not occur all round the globe, but are restricted to particular 

 regions and seasons, They do not appear to be formed over 

 the greater part of the Pacific, because the two trade-winds 

 there meet on the equator; and they are not formed over the 

 South Atlantic, because the two trade-winds (the north and 

 and the south) have not their meeting over that ocean at all. 

 But they are formed over the West Indian Sea, and most 

 numerously in summer and autumn, because in those seasons 

 the trade-winds of those seas have their meeting-place furthest 

 from the equator ; and for the same reason they are formed 

 at the same period of the year off the coast of California. 

 But the most instructive facts about their distribution are to 

 be found in the Indian Ocean and Chinese Sea. There the 

 meeting-place of the two trade-winds follows the sun as he 

 moves between the northern and southern hemispheres, and 

 the locality of the cyclones varies accordingly. In the summer 

 of the southern hemisphere (that is to say in the winter of 

 ours) they are formed over the Southern Indian Ocean : in the 

 summer of the northern hemisphere they are formed over the 

 Chinese Sea : and in the intermediate seasons, that is to say 

 in the months following the equinoxes, they are formed in the 

 intermediate locality, over the Bay of Bengal. 



This subject has been worked out in detail, by an examina- 

 tion of ships' logs, by Mr. Meldrum, whose results were read 

 to the Meteorological Society of Mauritius on 24th March, 1870, 



