428 PHYSICAL GEOGRAPHY OF THE SEA, AND ITS ]METEOROLOGY. 



cubic feet of ice one degree from any point below 32^, bas been 

 rendered latent in tbe process of liquefaction. Freeze tbis water 

 again, and tbis latent beat will become sensible beat, for beat no 

 more tban ponderable matter can be annibilated. But if, after tbe 

 cubic foot of ice bas been converted into water at 32°, we continue 

 tbe uniform supply of beat as before and at tbe same rate, tbe water 

 will, at the expiration of 180 minutes more, reacb tbe temperature 

 of 212^ — tbe boiling-point — and at tbis temperature it will remain 

 for 1030 minutes, notwithstanding the continuous supply of heat 

 during tbe interval. At the expiration of this 1030 minutes of 

 boiling beat, tbe last drop of water will have been converted into 

 steam ; but the temperature of the steam will be that only of the 

 boibng water ; thus, in the evaporation of every measure of water, 

 heat enough is rendered latent dming tbe process to raise tbe tem- 

 perature of 1030 such measures one degree. If this vapour be now 

 condensed, tbis latent heat will be set free and become sensible 

 heat again. Hence we perceive that eveiy rain-drop that falls 

 from tbe sky has, in its process of condensation, evolved beat enough 

 to raise one degree tbe temperatm'e of 1030 rain-drops. But if 

 instead of the liquid state, as rain, it come down in tbe solid state, 

 as bail or snow, then the beat of fluidity, amounting to enough to 

 raise tbe temperatm-e of 140 additional drops one degree, is also 

 set free. 



830. We have in tbis fact a clew to the violent wind which 

 The cause of the usuallv accompanics hail-storms. In the bail-storm 



boisterous weather f , . , \ -, . t i ^ o, j 



off Cape Horn. cougelation takcs place immediately aiter condensa- 

 tion, and so quickly that the heat evolved dm^uig the two processes 

 may be considered as of one evolution. Consequently, tbe upper 

 an has its temperature raised much higher than could be done by the 

 condensing only. So also the storms which have made Cape Horn 

 famous are no doubt osving, in a great measm^e, to tbis heavy Pata- 

 gonian rain-fall. The latent heat which is liberated by tbe vapour 

 as it is condensed into rain there, has the effect of producing a 

 great intumescence in the air of the upper regions round about 

 them, which in tmTi produces commotion in the air below. But 

 this is digressive. Therefore let us take up tbe broken thread, and 

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

 roy encountered in Patagonia to have taken place under the sup- 

 posed cloud region of the antarctic circle, and to have been bail or 

 snow instead of rain, then the total amount of caloric set free among 

 the clouds, in those 41 days of such a flood, would be enough to raise 



