TEADE-WINDS OF THE SOUTHERN HEMISPHERE. ggg 



tlie manner in which the demonstration has been conducted, the 

 presence of land in large masses there is called for ; and, if we 

 imagine it to be relieved by high mountains and lofty peaks, we 

 shall have in the antarctic continent a most active and powerful 

 condenser. 



If, again, we tax imagination a little farther, we may, without 

 transcending the limits of legitimate speculation, invest that un- 

 explored land with numerous and active volcanoes. If we sup- 

 pose this also to be the case, then we certainly shall be at no loss 

 for sources of dynamical force suf&cient to give that freshness and 

 vigor to the atmospherical circulation which observations have 

 abundantly shown to be peculiar to the southern hemisphere. 

 Neither under such physical aspects need it be any longer con- 

 sidered paradoxical to ascribe the polar tendency of the "brave 

 west winds" to rarefaction by heat in the antarctic circle. This 

 heat is relative, and though it be imparted to air far below the 

 freezing point, raising its temperature only a few degrees, its ex- 

 pansive power for that change is as great when those few degrees 

 are low down as it is when they are high up on the scale. 



If such condensation of vapor do take place, then liberation of 

 heat and expansion of air must follow, and consequently the ob- 

 lateness of the atmospherical covering of our planet will be alter- 

 ed ; the flattening about the poles will be relieved by the intu- 

 mescence of the expanded and ascending air, which, protruding 

 above the general level of the aerial ocean, will receive an impulse 

 equatorially, as well from the mere derangement of equilibrium 

 as from the centrifugal forces of the revolving globe. And so 

 this air, having parted with its moisture and having received the 

 expansive force of all the latent heat evolved in the process of 

 vaporous condensation, will commence its return toward the equa- 

 tor as an upper current of dry air. 



1021. Arrived at this point of the investigation, we may con- 

 template the whole system of these " brave west winds" in the 

 light of an everlasting cyclone on a gigantic scale. The antarc- 

 tic continent is in its vortex, about which the wind, in the great 

 atmospherical ocean all around the world, from the pole to the 

 edge of the calm belt of Capricorn, is revolving in spiral curves, 

 continually going with the hands of a watch, and twisting from 

 left to riorht. 



