THE WINDS OF THE SOUTHERN HEMISPHERE. 445 



wliicli in turn produces commotion in the air Lelow. But this is 

 digressive. Therefore let iis take up the broken thread, and 

 suppose, merely for illustration, such a rain-fall as King and 

 Fitzroy encountered in Talagonia to have taken place under the 

 supposed cloud region of the antarctic circle, and to have been 

 hail or snow instead of rain, then the total amoimt of caloric 

 set f]-ee among the clouds, in those 41 days of such a flood, would 

 be enough to raise from freezing to^ boiling six and a half times 

 as much water as fell. But if the supposed antarctic precipita- 

 tion come down in the shape of rain, then the heat set free 

 would be sufficient only to raise from freezing to boiling about 

 of as much water as the flood brought dow^n. 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 Patagonian 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 

 fell as snow or hail. The latent heat set free among the clouds 

 during these 41 days w^ould have been sufficient to raise from the 

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

 miles in area and 83i feet in depth. The unknown area of the 

 antarctic is eight millions of square miles. We now^ see how the 

 cold of the poles, by facilitating precipitation, is made to react 

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

 831. Offices of icebergs in the meteorological machinery. — Thus 

 we obtain another point of view from which we may contemplate, 

 in a new aspect, the icebergs which the antarctic regions send 

 forth in such masses and numbers. They are a part of the 

 meteorological machinery of our planet. The offices which they 

 perform as such are most important, 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 energy 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 liquefaction, has expended its meteorological energy in giving 

 dynamical force to the air, is like 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 grand meteorological 

 engine which drives the wind through his circuits, and tempers 



