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and tlie clouds of vapour in it, the heat, as soon as it came to the 

 earth, would be absorbed or ■would be radiated back into space ; it 

 is by the air that it is confined and rendered available for the 

 support of life. Necessary as the air is for us to breathe, it is 

 equally necessary to ■\varni us. We all know how winds carry 

 heat and cold, and can fancy, if we have not practical experience 

 of the effects of wind blowing from off a burning soil or snow-clad 

 plains. Xevertheless, the effect of wind would be little, were it 

 not backed up by the ocean. It is the ocean Avhich is the real store- 

 house of climatic heat ; and by means of currents it distributes it to 

 different localities. The power of dry air to carry heat, great as 

 we are apt to think it, is trifling as compared with that of the same 

 volume of water: in scientific phrase, water has a much greater 

 capacity for heat than air has. The quantity of heat Avhich will 

 raise the temperature of any given volume of water by 1° F. will 

 raise the temperature of more than 3000 times that volume of air 

 by 1°. The water absorbs the heat, carries it about with it where- 

 ever it goes, and gives it off economically : air, on the other hand, 

 throws it about with reckless profusion, lavishes it at once, regardless 

 of what becomes of it. It is this difference between the two that 

 gives the great climatic importance to the currents of the ocean. 

 In this country we are especially dependent on the Gulf Stream. 

 Some of you have, probably, been tempted now and then, to vote 

 the Gulf Stream a nuisance ; its absence would be a very much 

 greater nuisance. It has been calculated by Mr. Croll, that if the 

 North Atlantic, in temperate latitudes, were deprived of the heat 

 it receives from the Gulf Stream, its average temperature Avould 

 fall to something like 35° F. below the freezing point of fresh 

 water. If this calculation errs, it is in its moderation. It is at 

 least probable that instead of 3.5° we ought to say 100° F. It may 

 be left to you to imagine what a South-west wind in this country 

 would be like if it came to us from over such a frozen sea. As 

 things are, the average temperature of the extra tropical North 

 Atlantic is about 56° F., or 24:° above the freezing point of water ; 

 and this heat, continually renewed by the Gulf Stream, is con- 

 tinually given off into the air and carried over this country by the 

 south-west winds, which fortunately for us largely prevail over all 



