THE DRIFT OF THE SEA. 255 



bings of the sea-heart, which take place in consequence of the di- 

 urnal changes in its temperature, call in the sunshine, the cloud 

 without rain, with day and night, and their heating and radiating 

 processes. And to make the case as strong as to be true to na- 

 ture we may, let us again select one fifth of the Atlantic Ocean 

 for the scene of operation. The day over it is clear, and the sun 

 pours down his rays with their greatest intensity, and raises the 

 temperature two degrees. At night the clouds interpose, and pre' 

 vent radiation from this fifth, whereas the remaining four fifths, 

 which are supposed to have been screened by clouds, so as to cut 

 off the heat from the sun during the day, are now looking up to the 

 stars in a cloudless sky, and serve to lower the temperature of the 

 surface waters, by radiation, two degrees. Here, then, is a differ- 

 ence of four degrees, which we will suppose extends only ten feet 

 below the surface. The total and absolute change made in such 

 a mass of sea water by altering its temperature four degrees is 

 equivalent to a change in its volume of three hundred and ninety 

 thousand millions of cubic feet. 



552. Do not the clouds, night and day, now present themselves 

 to us in a new light ? They are cogs, and rachets, and wheels in 

 that grand and exquisite machinery w^hich governs the sea, and 

 which, amid all the jarrings of the elements, preserves in harmo- 

 ny the exquisite adaptations of the ocean. 



553. It seems to be a physical law, that cold-water fish are 

 more edible than those of w^arm water. Bearing this fact in mind 

 as we study Plate IX., we see at a glance the places which are 

 most faA^ored with good fish-markets. Both shores of North 

 America, the east coast of China, with the west coasts of Europe 

 and South America, are all washed by cold waters, and therefore 

 w^e may infer that their markets abound with the most excellent 

 fish. The fisheries of Newfoundland and New England, over 

 which nations have wrangled for centuries, are in the cold water 

 from Davis's Strait. The fisheries of Japan and Eastern China, 

 which almost, if not quite, rival these, are situated also in the cold 

 water. 



Neither India, nor the east coasts of Africa and South America, 

 where the warm w^aters are, are celebrated for their fish. 



554. Three thousand American vessels, it is said, are engaged 

 in the fisheries. If to these we add the Dutch, French, and En- 



