SiL'Dll-.S IX RADIO Bk'O.inC.IST I N.IXSMISSION 21.i 



The evidence for wave interference indicates that some of the energy 

 of received signals reaches its destinations by a circuitous route and 

 suggests that this route is by way of upper atmospheric regions. 



Quahty distortion may result from dynamic instability of the trans- 

 mitter. 



Fixed wave interference patterns in connection with shadows some- 

 times exist in daytime transmission. 



