Discussion on whistling tones from the earth

Summary form only given, as follows. The Bell Telephone Laboratories sent an expedition last summer to Newfoundland for the purpose of measuring the interference picked up on an 8-mile submarine cable in order to determine the amount of interference which might be expected on a transatlantic telephone cable terminated there. The same expedition is engaged in similar measurements this year in Ireland. The "swishes" discussed by Dr. Barkhausen were noted in both locations both day and night and were received on a loop of wire as well as on several different types of submarine cables. They are of two types, one descending in pitch, as mentioned by Dr. Barkhausen, and the other type ascending in pitch. The range of frequencies covered by the swishes was found to lie usually between 700 and 2000 p.p.s. The individual swishes, however, did not often exceed an octave in range. Another type of musical interference not as yet described by other observers, and called "tweeks" by our engineers because of their characteristic sound, occur only at night. They appear to the ear to be highly damped oscillations the frequencies of which are generally in the range between 1600 and 2200 p.p.s. We have tried to explain these tweeks as the result of multiple reflections between the earth and the Heaviside layer of a single static discharge and believed that this explanation was substantiated by the fact that they were never noticed during the daylight hours when the Heaviside layer is believed to be a less efficient reflector than during the dark hours. This conflicts somewhat with Dr. Barkhausen's explanation of the formation of the swishes since they appear to have the same general characteristic when noted at any time during the day or night. It might be expected that any phenomenon depending on reflection from the Heaviside layer would show characteristics during the night differing noticeably from those observed during the day. A more complete description of these phenomena as noted in Newfoundland is given in E.T. Burton's letter published in Nature, July 12, 1930.