514 BELL SYSTEM TECHNICAL JOURNAL 



"Quite audible swishing, crackling, rushing sounds" 



"A crackling so fine it resembled a hiss" 



"Similar to escaping steam, or air escaping from a tire" 



"Much like the swinging of an air hose with escaping air" 



"The noise of swishing similar to a lash of a whip being drawn 



through the air" 

 "Likened to a flock of birds flying close to one's head" 



Some of these phrases coincide with those used by us in describing 

 swishes. Certainly the correlation of sound descriptions is remarkable. 



Dr. J. Leon Williams, ^^ an observer of aurorae, comments on the 

 sounds thus: "... On several occasions I have heard the swishing 

 sound. The sound accompanies only a certain type of auroral display. 

 I have never heard this sound except when those tall, waving columns, 

 with tops reaching nearly to the zenith were moving across the sky. 

 . . . When these tall sweeping columns die down the sound, according 

 to my experience, disappears." 



Consideration has been given to the likelihood of swishes or other 

 appreciable audio frequency disturbances being produced by meteors. 

 Lindemann and Dobson " estimate the energy liberation of an average 

 meteor to exceed 3 kilowatts during the glowing period, and Skellet ^^ 

 states that a meteor may throw out an ionized trail extending laterally 

 to a distance of a few kilometers. It has appeared advisable to search 

 for magnetic disturbances which might show tonal qualities by 

 resonance between the meteoric trail and some established reflecting 

 surface. During two nights atmospherics were received with an audio- 

 frequency amplifier and a loop antenna, located at a point in New 

 Jersey. Observation of twenty-nine meteors, including six which 

 could be classified as quite bright, disclosed no correlation with the 

 sounds of audio-frequency atmospherics. 



Some Theories of Musical Atmospherics 

 In a paper entitled "Whistling Tones from the Earth " Barkhausen ^^ 



describes observations made during the World War on an atmospheric, 



which appears to have been the same as the descending swish heard 



by us. 



He states, "During the war amplifiers were used extensively on 



both sides of the front in order to listen in on enemy communications. 



... At certain times a very remarkable whistling note is heard in 



15 "The Sound of the Aurora," Literary Digest, 112, p. 28, February 20, 1932. 

 1^ Prof. F. A. Lindemann and G. M. B' Dobson, "Theory of Meteors," Proc. Roy. 

 Soc. Loud., 102, p. 411, 1923. 



'^Skellet, "Effect of Meteors," Phys. Rev., 37, p. 1668, 1931. 

 '^ H. Barkhausen, loc. cit. 



