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Mr. J. E. Taylor. Electric Earth-current [Dec. 16, 



The characteristic noises produced may be divided into five classes 

 resembling — 



(i) Uniform flowing or rushing of water : this is usually a day- 

 time disturbance, and is occasionally of considerable vigour. 



(ii) Intermittent crackling : an accompaniment of other disturbances. 



(iii) Bubbling and boiling of water : the usual form of nightfall 

 disturbance, but also frequently occurring in the daytime. 



(iv) Eocket disturbances. These are peculiar and characteristic, 

 having some resemblance to the sound produced by a rocket rising 

 in the air. They commence with a shrill whistle and die away in a 

 note of diminishing pitch. They vary in intensity, but always have 

 a similar duration of from 2 to 4 seconds ; are freely heard at night, 

 and only occasionally during the day. 



(v) Disturbances due to high frequency effects, inaudible on the 

 telephone, but evidenced on the coherer, magnetic detector, or other 

 form of Hertzian receiver. 



These various disturbances were, for some time, very puzzling to 

 me; but on perusing Professor J. J. Thomson's paper, read at the 

 Royal Institution on 19th April, 1901, it speedily appeared highly 

 probable that they were due to electrical effects produced in the 

 atmosphere by the ionisation caused by solar radiations and the 

 reaction on this ionisation by electric stresses in the atmosphere. 

 The rocket disturbances, though they are probably not in them- 

 selves due solely to ionisation, furnished the first clue to this explana- 

 tion. They are characteristic of an initial high velocity rapidly 

 damped and ultimately dissipated. They have the same duration as 

 is usually associated with the passage of a meteor across the heavens, 

 and the assumption is that they are actually caused by the passage, in 

 sufficient proximity, of meteoric bodies which set up electrical 

 discharges in the upper rarefied atmosphere, these discharges inducing 

 electric currents in the sea and collected therefrom by the circuit. 



Assuming this explanation, it might reasonably be asked why such 

 disturbances are not equally evident during the daytime as at night. 

 The answer lies in the screening effect of the ionised (and therefore 

 conducting) air during the daytime and the absence of such screening 

 at night. 



Professor J. J. Thomson has shown, in a modification of the well- 

 known cloud experiment, how the ionisation of a gas may be cleared 

 up or dissipated by an electric field. Doubtless the electric fields to 

 which thunderstorms are due produce similar effects in the atmo- 

 sphere on nature's gigantic scale. Hence we may expect, as is presum- 

 ably the case, that the screening referred to above may sometimes be 

 suspended for a time, even during broad daylight, and the rocket 

 disturbances evidenced among others. 



Now this assumption of a reaction between the electric stresses in 



