THE WINDS OF THE SOUTHERN HEMISPHERE. 429 



from freezing to boiling six and a half times as much water as fell. 

 But if the supposed antarctic precipitation come down in the shape 

 of rain, then the heat set free would be sufficient only to raise from 

 freezing to boiling about 5J as much water as the flood brought 

 down. We shall have, perhaps, a better idea of the amount of 

 heat that would be set free in the condensation and congelation in 

 the antarctic regions of as much vapour as it took to make the Pata- 

 gonian rain-fall, if we vary the illustration by supposing this rain- 

 fall of 153.75 inches to extend over an area of 1000 square miles, 

 and that it feU as snow or hail. The latent heat set free among the 

 clouds dm'ing these 41 days would have been sufficient to raise from 

 the freezing to the boiling point all the water in a lake 1000 square 

 miles in area and 83 J feet in depth. The unknown area of the ant- 

 arctic is eight millions of square miles. We now see how the cold 

 of the poles, by facihtating precipitation, is made to react and develop 

 heat to expand the air, and give force to the winds. 



831, Thus we obtain another point of view fi'om which we may 

 Offices of icebergs in contemplate, in a new aspect, the icebergs which the 



the meteorological .^ '. t r> ii • i -i 



machinery. autarctic rcgious seuQ lorth m such masses and num- 



bers. They are a part of the meteorological machinery of our 

 planet. The offices which they perform as such are most im- 

 portant, and oh, how exquisite ! While they are in the process of 

 congelation the heat of fluidity is set free, which, whether it be 

 liberated by the freezing of water at the surface of the earth, or 

 of the rain-drop in the sky, helps in either case to give activity and 

 energ}^ to the southern system of circulation by warming and 

 expanding the air at its place of ascent. Thus the water, which 

 by parting with its heat of hquefaction, has expended its meteoro- 

 logical energy in giving dynamical force to the air, is hke the 

 exhausted steam of the engine ; it has exerted its power and become 

 inert. It is, therefore, to be got out of the way. In the gi^and 

 meteorological engine which drives the v^ind through his circuits, 

 and tempers it to beast, bird, and plant, this waste water is collected 

 into antarctic icebergs, and borne away by the currents to more 

 genial climes, where the latent heat of fluidity which they dispensed 

 to the air in the frigid zone is restored, and where they are again 

 resolved into water, which, approaching the torrid zone in cooling 

 streams, again joins in the work and helps to cool the air of the 

 trade- winds, to mitigate chmate, and moderate the gale. For, if 

 the water of southern seas were warmer, evaporation would be 

 greater; then the S.E. trade-winds would defiver vapour more 



