1869.] Meteorology. 445 



that most of, if not all, the atmospherical disturbances experienced 

 in those seas may be referred to the mutual interference of the two 

 great currents of air, whether these be the ordinary polar and 

 equatorial currents, the S.E. and N.W. winds of the South Tem- 

 perate Zone, or the S.E. trade and the N.W. monsoon met with 

 nearer the equator. When these opposite currents are flowing in 

 parallel channels at the earth's surface, the resulting action on the 

 atmosphere in general differs according to their position as regards 

 latitude. When the bed of the polar current is in a latitude higher 

 than that of the equatorial, i.e. when the S.E. wind lies to the 

 southward of the N.W. wind, atmospherical pressure has a tendency 

 to decrease between them, and ultimately the wind begins to cir- 

 culate round the area of depression, in the direction of the hands of 

 a watch. A cyclone is ultimately formed, and in it the force of the 

 wind is stronger at the centre than at the circumference. When 

 the position of the currents is reversed, a barometrical maximum is 

 produced, around which the wind revolves in the direction opposite 

 to that of the hands of a watch. In short an "anticyclone" is 

 formed, in which the wind-force is usually very light in the centre 

 but stronger outside. It is hardly necessary to observe that as we 

 are dealing with the Southern Hemisphere, the conditions of the 

 direction of the wind's motion are exactly the reverse of what 

 obtains in this hemisphere. Mr. Meldrum asserts that cyclones 

 invariably hme their origin as we have described. They commence 

 at the southern edge of the N.W. monsoon, and travel obliquely 

 across the S.E. trade. 



If this theory be found to be completely trustworthy, we may 

 hope that it will be possible to assign an origin to the West Indian 

 hurricanes, which will be more satisfactory than that given hypo- 

 theticaUy by Dove, who attributes them to the fact that by some 

 means or other a portion of the upper current (antitrade) between 

 the tropics has been forced out of its proper stratum into the true 

 trade wind below it, so that an eddy, ultimately resulting in a 

 hurricane, has been formed. This is, after all, something like the 

 convulsion theories of the older geologists. If we can iind that 

 ordinary causes are capable of producing certain eflfects, it is well 

 to satisfy ourselves, whenever these eflfects are observed, that these 

 causes were not in operation, before we call in a deus ex maehind 

 of any sort to produce the required action. 



We see from the report of a lecture delivered at the Eoyal 

 Institution on April 30 by Mr. Scott, that the Meteorological Office 

 has been led, independently of Mr. Meldrum, to results similar to 

 his, and we may hope that useful results will come out of the 

 inquiry. 



The Journal of the Scottish Meteorological Society for January 

 contains a good paper by Mr. Buchan " On the Mean Monthly and 



2 H 2 



