526 NATURE'S TEACHINGS. 



it a large stone, called the Echo-stone. Any one sitting on 

 this stone, and singing, speaking, or whistling towards the 

 house, heard every sound repeated, as if in mockery. 



The celebrated Whispering Gallery in St. Paul's Cathedral 

 is nothing but an ordinary Echo, though so intensified by the 

 process of radiation, that the sound is transmitted from one 

 side of the dome to the other, just as light or heat is reflected 

 from concave mirrors. 



