472 PHYSICAL GEOGliAPHY OF THE SEA, AND ITS METEOROLOGY. 



temporatiire raised high by day and cooled low down by night; 

 but the most powerful sun, after beating down all day with its 

 fiercest intensity upon this liquid covering, has not power to 

 raise its temperature more than three or four degrees. This 

 covering serves as a reservoir for the solar heat. In the depths 

 below it is concealed from the powers of intense radiation, and 

 held by the obedient ocean in readiness to be brought to the sur- 

 face from time to time, and as the winds and the clouds call for 

 it. Here it is rendered latent by the forces of evaporation, and 

 in this form, having fulfilled its office in the economy of the 

 ocean, it passes off" into the air, there to enter, in mysterious 

 ways, upon the performance of its manifold tasks. 



890. Actinic processes. — As evaporation goes on by day or night, 

 the upper stratum is rendered heavier by reason of both the heat 

 and the fresh water borne away by evaporation ; the upper water 

 having been thus rendered both Salter and cooler, has its specific 

 gravity increased so much the more. On the other hand, the 

 strata below, receiving more heat by day than they dispense again 

 by radiation day and night, grow actually warmer and speci- 

 fi.cally lighter; and thus, by unseen hands and the "clapping of 

 the waves," the waters below are brought to the surface, and 

 those on the surface carried down to unknown depths ; and thus, 

 also, we discover new and strange processes which have been 

 ordained for the waters of the ocean in their system of vertical 

 circulation. 



891. TJie reservoirs of heat. — Thus we arrive at the conclusion 

 that the ocean is the great reservoir of sensible as the clouds are 

 of latent heat. That in those two chambers it is innocuously 

 stored, thence to be dispensed by processes as marvellous as they 

 are benignant and wise, to perform its manifold offices in the 

 economy of our planet ; it is this heat which gives " his circuits " 

 to the winds and circulation to the sea ; it is it that fetches from 

 the ocean the clouds that make " the earth soft with showers." 

 Stored away in the depths of inter-tropical seas, it is conveyed 

 along by " secret paths " to northern climes, there to be brought 

 to the surface in due season, given to the winds, and borne away 

 to temper the climates of western Europe, clothing the British 

 Islands as they go, in green, and causing tliem to smile under the 

 genial warmth even in the dead of winter. 



892. xin ojjlce for ivaves in the sea. — Thus perhaps we discover 

 a new office for the waves in the physical economy of the ocean. 



