THE OCEAN . 151 



miles. It is an interesting fact that the highest mountain 

 peak is about five miles above sea level, so that the largest 

 variation in the surface of the earth is about ten miles. Water 

 in large masses affects the climate of a locality to a very 

 marked degree. It acts as a sort of balance wheel to the 

 temperature, retarding its rapid rise as well as prolonging the 

 warmth far into the winter time. We learned, under Con- 

 vection of Heat, that a whole mass of water must be warmed 

 before we can raise any part to a high temperature. We also 

 learned that it takes more heat to warm water than any other 

 substance, and that, having become warm, water stays warm 

 longer than any other substance. It is quite probable that if 

 it were not for the ocean, the earth would become unbearably 

 hot, and also it is quite likely that during the cold weather 

 the temperature would fall far below that at which life can 

 be maintained. 



The ocean serves as a pathway for trade, and a country is 

 fortunate which has a long coast line with many inclosed 

 bays and harbors. Transportation by ocean is necessarily 

 cheaper than by rail, because there are no roadways to main- 

 tain, and in the case of sailing vessels there is no expense for 

 power. See Section 202, Nature and Business. 



On account of the mobility of water, storms at sea become 

 much more dangerous than storms on land, for the water is 

 picked up, forming large billows, which, by reason of their 

 mass, may overwhelm and destroy the vessels; and the wind, 

 having an unimpeded pathway, blows much more fiercely on 

 the open ocean than on the land. 



The ocean, because of its unlimited supply of fish of all 

 kinds, is a never failing source of income to those who make . 

 fishing their business. Thus it is that we are dependent upon 

 the ocean in more ways than are at first manifest. 



