50 Our Surroundings 



pitcher onto the blades of a toy water wheel. The pressure of the 

 falling water causes the wheel to revolve. Energy, that was po- 

 tential in the water when it left the mouth of the pitcher, is re- 

 leased when the water strikes the wheel and exerts this pressure. 

 In the same way, the water at the crest of Niagara Falls has po- 



AUSABLE CHASM 



The water has worn away the solid rock. 



J. A. Glenn. 



