426 The Origin of the Great Cyclones. [O¢tober, 
Indian Ocean. Sailors have long known this influence, and 
called it ‘“‘the backing of the monsoon.” ‘This backing 
continually enfeebles the N.E. trade, finally absorbs and 
turns it right about to the opposite point of the compass 
from which it was blowing. Observation shows that the 
S.W. monsoon then works its way backwards through the 
northern trade-wind belt to its extreme equatorial limit. 
When this process is complete, the S.E. trade, on reaching 
the Equator, finds no adversary to resist its progress, and 
sweeps on in the general draught of the S.W. monsoon to 
swell its force. From May to August all goes smoothly 
enough. The monsoon has everything its own way, and 
the seaports of India have their harbours flooded with the 
sea, and the mountains of India are drenched with torrential 
rainfalls. In August the monsoon begins to change, and 
then begins the same conflict, but on a somewhat more 
terrific scale than we have witnessed in the Atlantic off the 
Windward Islands in the same month between the aspiring 
and impetuous S.E. trade and its northern congener. 
In my first paper on this subjeét, published more than a 
year ago, I said, ‘‘ In the Bay of Bengal the typhoon would 
follow in August, from the conflict of the two lateral 
currents of the South-East trade, and the North-East trade 
enfeebled by the counter monsoon influence. It is doubtless 
this enfeebling of the North-East trade that renders it an 
easier prey to the impact of the South-East trade; and 
this explains the violence of typhoons, which is greater 
than that of West India hurricanes.” 
Within a few weeks my attention has been called to the 
following brief letter in ‘‘ Nature” from the distinguished 
geographer, Mr. Joseph John Murphy, F.G.S., which, as an 
able argument in point, is here partially quoted : — 
‘Origin of Cyclones—In ‘‘ Nature” of the 23rd June, 1871, 
there is an account of a paper, by Mr. Meldrum, on the 
origin of storms in the Bay of Bengal, showing reason to 
believe that the cyclones of the Bay of Bengal and the 
Southern Indian Ocean originate in the meeting of the 
trade-winds of the northern and southern hemispheres at 
some distance north or south of the Equator. I do not 
know of any equally complete evidence on the subjeCt for 
the cyclones of other parts of the world, but there is very 
strong reason for thinking that they always so originate. 
The two trade-winds meet in the Atlantic a little to the 
north of the Equator; for this reason cyclones are fre- 
quent in the West Indies, but unknown over the South 
