2 ART. 7.-Y. HOMMA : 



Every one looking at the photographs will be struck by the 

 most irregular and capricious manner, in which the potential varies 

 from instant to instant. (See PL. I.) This fact, together with the 

 observations of Lord Kelvin and otliers that at two stations distant 

 from each other by more than 100 m., no similarity in the variations 

 could be detected, suggests to us that the principal causes of the 

 phenomenon are located not very far from the earth, but perhaps 

 within a few kilometres from, and possibly just near the surface. 



On examining the figures given in the Report, we see at once 

 that the cold seasons show a decided tendency to have higher 

 potentials than the warm. While fully recognizing this tendency, 

 we feel some hesitation in accepting these figures as representing the 

 genuine values of the potential at all seasons. Probably defective 

 insulation of the instrument in the warm and wet season has some 

 part in the etfect. 



Undoubtedly the diurnal variation is much more faithfully 

 represented. Here we see two maxima and two minima, somewhat 

 resembling the variation of the atmospheric pressure, with which the 

 phenomenon has probably a close connection. As to the time of 



