THE OCEAN. 



325 



It is certain, however, that earthy impregnations will not always account for the hue of 

 lakes and rivers, for the Jumna and the Ganges both take their rise in the snow, flow 

 almost in parallel lines, run through nearly a similar soil, and yet the water of the one is 

 pure as crystal, and that of the other yellow and thick. The Bala-Pool, or Pimble-Mere, 

 is an exception to the general aspect of the lakes of Wales, its water being so pure, that 

 the nicest chemical tests can detect scarcely any quantity of foreign admixture. It refuses 

 to mingle with the tan-coloured Dee, whose waters run through it in a streak of almost 

 inky blackness. 



CHAPTER VIII. 



THE OCEAN. 



ROM the land-enclosed waters 

 of the globe, we now pass 

 to consider those which en- 

 close the land, bccupying the 

 greater part of the surface of 

 the earth, in various places 

 to an unknown depth, and 

 presenting a thousand inter- 

 esting and astonishing fea- 

 tures. However occasionally 

 disastrous by its tempests to 

 human life and property, the ocean is 

 essential to the existence of man and of 

 all vegetation, purifying the atmosphere 

 he breathes by its constant motions, and sending off 

 from its immense reservoir a perpetual supply of 

 vapours, which condense into clouds, and are the 

 sources of moisture and fertility to the soil. Nor is the 

 facility afforded by the great deep for the intercourse of distant 

 nations an unimportant circumstance, while numerous marine 

 productions, in the hands of civilisation, minister to the comfort 

 and improvement of society. Owing to the enterprise of sci- 

 entific individuals, to commercial adventure, and to costly ex- 

 peditions fitted out by different governments, the surface of the 

 ocean has been largely traversed, and the sinuosities of its coasts 

 explored, though the line of its circumference has not yet been 

 fully traced, and various parts of it which have been visited 

 have not been accurately surveyed. The passage of the Polar 

 Sea to the north of America has hitherto baffled the skill and hardihood of our coun- 

 trymen, though the accomplishment of it is probably nigh at hand ; and the configu- 

 ration of its shores to the north of Asia is a very recent geographical achievement, due 



Y 3 



