On Rapid Periodic Variations of Terrestrial Magnetism. g5 



7. The observed results may probably be explained by the 

 fluctuations of the horizontal electric current existing in the upper 

 atmosphere, and causing tlie diurnal variation of the terrestrial 

 magnetism. 



8. Two diverging lines of theoretical considerations intended 

 for the explanation of the phenomena in question, are given; 

 the one based on the assumption of the simultaneity of the 

 phenomena in a wide area, and the other on the assumption of 

 a progressive nature of the pulsations, though some evidences 

 at hand seems to speak rather strongly against the latter 

 assumption. The results of the discussions turn out rather 

 favourable for the hypothesis of simultaneous disturbances than 

 for that of progressive waves. If the simultaneity be universally 

 establislied, the phenomena may probably be accounted for by 

 the fluctuation of the atmospheric current, in its intensity as well 

 as in its location. The fluctuation must then very probably be 

 attributed to the more or less vertical oscillation of limited portions 

 of the upper atmosphere. If sucli be actually the case, we 

 have in the phenomena of the magnetic pulsations a very 

 valuable clue for studying the physical conditions of the upper 

 atmosphere unattainable by the usual means, and then, it may 

 be hoped, for following the hourly or daily changes occurring 

 in the remotest part of our atmosphere. 



Published May 25th, 1917. 



