500 



PELL SYSTEM TECIISICAI. JOl'RSAL 



i\ 



v'VV 





ilh^ 



Monthly Averages of Diurnal Variation of Noise 



New Southgate, England 25,000 Cycles 



Aug., 1923— Feb., 1925 



Monthly .Averages of Diurnal Variation of Noise 



New Southgate, Kngland 37,000 Cycles 



Oct., 1923— Feb., 1925 



