Solar Energy in Relation to Ice. 141 



The same energy which evaporates the sea-water sets the 

 winds in motion ; and one of the results of this manifestation 

 of Solar Energy is, generally, that the prevalent winds not 

 only drag the surface layers of sea-water along with them in 

 the same direction as they are moving themselves, but that 

 they are also the chief agents concerned in carrying forward 

 the aqueous vapour which the Sun's heat has just before 

 distilled. As the winds trail the upper layers of warm sea- 

 water after them, and as, at the same time, they waft the 

 aqueous vapour from torrid zones to temperate, or from 

 temperate to frigid, they are themselves constantly receiving 

 heat from both of these sources in quantities which serve to 

 maintain their temperature at a higher point than would 

 otherwise be the case. As, further, their high temperature 

 enables them to take up more aqueous vapour as they 

 advance, they arrive at our shores abundantly charged 

 with both sensible and latent heat. The slow rate at which 

 water parts with its heat acts as an important factor in 

 this case. It is well known that the sea does not reach 

 its maximum surface temperature until well into August — 

 nearly two months after the sun reaches it maximum 

 declination ; and also that, owing to its very slow rate of 

 cooling, the sea-water has not parted with all the heat 

 absorbed during the previous summer until well on into 

 February. In the mean time, the winds have trailed the 

 waters which have been heated in low latitudes many 

 degrees farther north, and have, in like manner, transported 

 the warm water from these latter places to higher latitudes, 

 and so on ; the water warmed in each zone of latitude being 

 transferred from that to the zone adjoining farther north. 

 By thus working, as it were, in relays, such combined aqueous 

 and aerial currents as the "Gulf Stream" convey enormous 

 stores of heat to north-western Europe. 



It has not been clearly proved that any of this heat that 

 reaches our shores actually originated in the Gulf of Mexico, 

 or perhaps within the Tropics at all ; nor is it certain, even 

 if that were the case, that the heat that is conveyed to us 

 by the "Gulf Stream" represents the effects of Solar Energy 

 which had been in operation only a few months before. No 



