271 THE ATMOSPHEEE AND METEOEOLOGY. 



employed. This term can be equally applied to the hurricanes (in 

 Caribbean, aracan, huiranviican) of the West Indies, to the tornados 

 of the coasts of Africa, to the typhoons (ti-foong) of the Chinese Seas, 

 to the revolving tempests of the Indian Ocean, and to the great 

 gales of Western Europe. Still, we principally designate by the name 

 of cyclone those whirlwinds which are developed according to a regu- 

 lar curve, either in the sea of the Antilles, or in the Indian Ocean, or 

 more rarely in the Pacific Ocean. 



Meteorologists have ascertained that the revolving tempests of the 

 equatorial regions occur especially at the time of the reversal of the 

 regular winds. Poey tells us that out of 365 hurricanes which have 

 blown in the West Indies from 1493 to 1855, 245 (more than two- 

 thirds) have taken place in October, that is to say, during the months 

 when the strongly-heated coasts of South America began to attract 

 towards themselves the colder and denser air of the northern con- 

 tinent.* In the Indian Ocean it is principally towards the vernal 

 equinox, at the time of the change of the monsoons, and after the 

 great heat of the summer, that the cyclones are most nimierous. 

 In the list of hurricanes in the southern hemisphere drawn up by 

 Piddington and completed by Bridet, not a single cyclone is men- 

 tioned for the months of July and August ; more than three-fifths of 

 these phenomena have taken place during the three first months of 

 the year. It is at this epoch of the change of the seasons that the 

 powerful aerial masses, charged with electricity, engage in strife for 

 the supremacy, and by their encounter produce those great eddies 

 which are developed in spirals across the seas and the continents. 

 Still the whirlwind never occupies in height more than a small part 

 of the atmosphere. According to Bridet the mean height of the 

 hurricanes of the Indian Ocean is rather less than two miles ; and 

 according to Kedfield it is very rare that a cyclone would prevail at 

 the same time at the level of the sea and at more than a mile above 

 it. Ordinarily the revolving stratum of air is much less thick; 

 occasionally it is even so thin that the sailors in a ship, whirled round 

 by a cyclone, see above their heads the blue sky or the stars. Above 

 this storm the winds follow their regular path. 



These sudden movements of the air are perhaps, after the great 

 volcanic eruptions, the most terrible meteorological phenomena of our 

 planet, and we cannot be astonished that in the mythology of the 

 Hindoos, Rudra, the chief of winds and storms, should have ended by 

 becoming, under the name of Siva, the god of destruction and death. 

 * Poey, Talk Chromlogiqiie dcs Ouragans, &c., 1862. 



