1872.] The Origin of the Great Cyclones. 425 
moving towards the N.N.W. will, on coming in contact 
with the trade-wind moving towards the S.W., have a 
general direction towards the W. by N. (the regular path 
of the West India hurricane), and will at the same time 
fulfil all the conditions necessary to generate a cyclonical 
motion in the direction E., N., W., and S.,”z.e., against the 
hands of a watch. According to the old Redfield Law of 
Storms, Mr. Buchan, discussing the moving dust whirlwinds 
and pillars of sand so frequent in the East, says, “‘ The 
direction of the eddy of the whirlwind, especially when of 
small diameter, differs from the rotation of the winds in a 
storm, in that it may take place either way according to 
the direction of the stronger of the two winds which gave 
rise to it. Thus, suppose a whirlwind produced by the 
brushing of a north against a south wind, then if the north 
wind be the stronger, and on the west, the whirl will be 
in the direction of the hands of a watch; but, if the south 
wind be the stronger, the eddy will turn in the opposite 
direction* (cyclonical). In the theory, the south wind (the 
S.E. trade), as we have seen, is the stronger. Dové himself, 
though advocating a different view, admits the mechanical 
eerrectness of this; and, indeed, were this the place, it 
were easy to demonstrate its truth by a direct appeal to 
mechanical law. 
(5). The TyPHoons of the East Indies and of the Southern 
Indian Ocean are explained by the theory now advanced, 
as happily as are the hurricanes of the West Indies. 
According to the testimony of all writers, which may be 
stated in the words of Professor A. Keith Johnston, 
**Cyclones originate in the space between the Equator and 
the tropics near the equatorial limit of the trade-wind 
during winter, when these winds are irregular, and during 
the changes of the monsoons.”’t Out of all the hurricanes and 
typhoons remembered and chronicled since the year 1600, 
only three or four have occurred near the winter or summer 
solstice. 
It is, of course, impossible here to discuss the exact 
limits of the monsoons in the East Indies. It is only 
necessary to examine any monsoun-chart to see that the 
region of vernal and autumnal monsoon changes and the 
typhoon regions perfectly coincide. When the South-West 
monsoon begins in the spring to blow over India it speedily 
draws upon the belt of N.E. trade-winds in the North 
* Handy Book of Meteorology, pp. 305, 306. 
+ Physical Atlas, p. 62. 
VOEs ile. (N.Ss) 31 
