rK.I.\S.ll/..l\llC N.IIUO I F.I. Ill' IK) ST. Ili.lXSMISSIOS 501 



Monthly Averagt-s of Diurnal Variation of Noine 



New Southgate, Englaml 57,00() Cycles 



1923—1924 



Monlhiy Average of Diurnal Variation of Noise 

 Belfast, Maine 15,000 Cycles 



1924 



