146 



FIRST YEAR SCIENCE 



It bears' man's commerce across the seas and by the power 

 of the water which it has borne over the land, furnishes 

 him the means for his manufacturing. It scatters the 

 seeds over the fields and sweeps the smoke and foul air 

 away from his cities. 



EFFECT OF WIND ON THE GROWTH OF TREES. 

 The trees have grown in the direction in which the prevailing wind blows. 



72. The Effect of the Earth's Rotation on Winds. Experi- 

 ment 80. Revolve a globe from left to right and while it is revolv- 

 ing draw a piece of chalk from the pole toward the equator. Does 

 the line as marked on the globe follow a meridian ? What is its gen- 

 eral direction in lower latitudes ? 



The rotation of the earth affects the direction of move- 

 ment of all bodies free to move over its surface. Thus if 

 a current of air starts from the north pole to flow south, it 

 will, as it goes along, tend to move toward the right,-and so 

 when it reaches middle latitude it is no longer moving 

 south but southwest. Why this is so can be fairly well 



