CHAPTER III 

 THE HYDROSPHERE 



ONE of the first impressions that one gets on visiting 

 the coast-line of a country is the vastness of the ocean. 

 It stretches away to the horizon, and if we ascend a 

 hill or high cliff and look seawards, it only appears 

 vaster still. 



Standing, for example, on the Land's End in Corn- 

 wall, or on the cliffs of the west of Ireland, we can 

 look away towards the west and see nothing but the 

 apparently limitless waste of waters, and should we sail 

 away from the shores of these islands, we can travel 

 westward for a week at the speed of an ordinary train 

 without reaching its farther boundary. 



The waters of the ocean do not, of course, cover the 

 whole of the Earth's surface as is the case with the 

 atmosphere which was described in the last chapter, 

 being gathered together under the influence of the laws of 

 gravitation in the great hollows, forming oceans and seas. 



These submerged areas form nearly three-quarters of 

 the whole surface, and have been divided by the late Sir 

 John Murray into an abyssal area from two to five miles 

 deep, covering one-half of the total area of the planet, 

 and a transitional area of comparatively shallow water 

 covering three-sixteenths. The remaining five-sixteenths 



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