446 THE PHYSICAL GEOGRAPHY OF THE SEA. 



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 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 meteoro- 

 logical energy in giving dynamical force to the air, is like the ex- 

 hausted 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 it to beast, bird, and plant, this waste water is collect- 

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

 genial climes, where the latent heat of fluidity which they dis- 

 pensed 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 climate, and moderate the gale. 

 For, if the water of southern seas were warmer, evaporation would 

 be greater; then the S.E. trade-winds would deliver vapor more 

 abundantly to the equatorial calm belts: this would make pre- 

 cipitation there more copious, and the additional quantity of heat 

 set free would give additional velocity to the inrushing trade- 

 winds. Thus it is, as has already been stated, that, parallel for 

 parallel, trans-equatorial seas are cooler than cis-equatorial ; thus 

 it is that icebergs are employed to push forward the winds in the 

 polar regions, to hold them back in the equatorial ; and thus it is 

 that, in contemplating the machinery of the air, we perceive how 

 icebergs are "coupled on," and made to perform the work of a 

 regulator, with adjustments the most beautiful, and compensations 

 the most exquisite, in the grand machinery of the atmosphere. 

 ' 832. With this illustration concerning the dynamical force 

 Tiie antarctic calm wliich thc wiuds dcrivc from the vapor taken up in 



place a region of con- ^ . ^ ^ ^ 



tt ant precipitation, ouc climate auQ transported to another, we may 

 proceed to sketch those physical features which, being found in 

 the antarctic circle, would be most favorable to heavy and con- 

 stant precipitation, and, consequently, to the development of a 

 system of aerial circulation peculiarly active, vigorous, and regu- 

 lar for the aqueous hemisphere, as the southern in contrast with 



