OUR PHYSICAL 

 WORLD 



A Source Book of Physical Nature- Study 



By 

 ELLIOT ROWLAND DOWNING 



The School of Education, University of Chicago 



WITH A CHAPTER ON RADIO COMMUNICATION 

 BY FRED G. ANIBAL 



Central High School, Kansas City, Mo. 

 Formerly Radio Officer, United States Air Service 



THE UNIVERSITY OF CHICAGO PRESS 

 CHICAGO ILLINOIS 



