16 ART. 7.— Y. HOMMA : 



EFFECT OF SNOW. 

 In the case of a snowlall, the variation is much more reo-ular, 

 though no less energetic, (hiin in the case of rain. The potential now 

 increases in the positive direction, tlien decreases to zero and to 

 extreme negative values, and then back again, etc. (See Fig. 7.) 

 Whence may come such a quasiperiodic nature ? As a matter of fact, 

 the snowfall is attended with a greater or less periodicity ; thus during 

 one interval, there will be a heavv fall of fine snow : durinsf next 

 time the violence decreases and there will fall only scattered flakes. 

 May not this fact have some connection with the above described 

 manner of variation ? On Feb. 25, 1901, there was a steady snow- 

 fall in tlie afternoon, and at 2 p.m., I measured the potential of the 

 air outside the laboratory, and f^iind it to be positive. At 4 p.m. the 

 fall began to be scanty, and at 4.20 p.m. the potential was again 

 measured, and was found to have a very great negative value. 

 Since this was the only occasion I experimented on, it is unsafe to 

 draw any conclusion from it, and 1 hope to make similar observations 

 on the next available occasion. 



ABNORWAL INDICATIONS. 



There were two remarkable instances (see l^L. LV) in which 

 the potential showed abnormally great variations in b(3th directions, 

 positive and negative, while there was no precipitation, no tliunder and 

 no lightning. On May 2(), a little before 4 p.m. the potential began 

 to decrease suddenly, reaching extreme negative values at and near 

 4 p.m. Then it began to rise Jind crossed the zero-line at 4.20 p.m. 

 and then as suddenly increased t(j i-eacli its extreme ])Ositive value a 

 little before 5 p.m. It then began to decrease, became negative again 

 at and near 5.30 p.m., and then increased, and recovered its usual 

 course at (i p.m. 



