170 



BELL SYSTEM TECHNICAL JOURNAL 



summer extending from Deal Beach, N. J., to New Southgate, London. 

 The British Post Office in January started sending on a return short 



Fig. 3 — Showing both long and short wave routes 



wave circuit from Rugby, England, which is now being received at 

 Cliffwood, N. J., but is not yet ready for service. 



The right-hand drawing of Fig. 4 shows, necessarily on a logarithmic 

 scale, approximately the frequency ranges covered by radio as we now 

 know it. At the lower end are the long waves used in long distance 



COSMIC RAYS(MILLIKAN) 



LIGHT WAVES 



HEAT WAVES 



RADIO WAVES 



SOUND WAVES 



ULTRA VIOLET 

 VISIBLE 

 INFRA RED 



EARTHS ROTATIONAL PERIOD 

 earth's PERIOD OF REVOLUTION \\.^q^ 

 DONATl'S COMET CPERIOD=2000YRS) . 



WAVE LENGTHS USED COMMERCIALLY 

 (I928J 



16 METERS I 

 SHORT WAVES B 22 METERS \ l^^^lSi^^'^'^ 



,10,000,000 33 METERS J TELEPHONE 



-I 1,000,000 



LONG WAVES 



(BROADCASTING) 



5000 METERS 



Ttransatlantic 

 "itelephone 



FREQUENCY SPECTRUM 



RADIO SPECTRUM 



Fig. 4 — Showing two plots on a logarithmic scale, one the radio frequency range, 

 the other a general plot of frequencies 



