354 



ATSIOSPnEEIC ELECTRICITY. 



These observations concur in showing that the rains which foil 

 •while the north winds are prevalent are more frequently positively 

 electrified than negatively, while the contrary is exhibited by the 

 south winds. The maximum coincides with the north wind and the 

 minimum with the S. or SW. wind. 



Although in fSchubler's observations, mentioned above, the pro- 

 portion of the number of days of positive rain to that of days of nega- 

 tive rain was as 100 to 155, yet the mean force of the positive electri- 

 city was greater than that of the negative in the proportion of 69 to 43. 

 This superiority of positive over negative electricity was observed in 

 all the winds, as may be seen by the following table, in which the 

 mean forces of the two electricities are given for each : 



Winds. 



N. E. 

 E ,.. 

 S. E. 

 S 



s. w. 

 w... 



N. \\ 



MEAX rOUCE OF Ef-ECTEICITY. 



+ 69 



We think we may pass in silence the explanation which Schiibler 

 gave of the diiferent results to which his observations conducted him 

 on the electricity of rain, since it rests on the hypothesis that the vapor 

 at the moment of its formation receives positive electricity. Besides, 

 it is evident that an explanation ought not be hazarded until these 

 first observations shall be confirmed by new observations, in which 

 the indications furnished by the instruments shall be more in accord- 

 ance with the actual intensity of the electricity which is to be 

 measured. 



§ 2. — 0/ atmospheric electricity during storms. 



Atmospheric electricity has its greatest tension in stormy weather, 

 and is often so great that the instruments are insufiScient to measure 

 it. The currents are sometimes so intense that they demagnetize the 

 needles of the rheometers, and tear in pieces the gold leaves of the 

 electrometers.* This powerful tension is exhibited also by the flashes 

 of lightning, the sparkling rain, and the luminous effects which 

 appear at the extremities of conducting bodies. 



These observations concur in showing that electricity undergoes 

 frequent and sudden variations in its nature as well as in its intensity 



^ Comptes Rendus, tome III, page 147, and tome XIII, page 211. 1836 and 1841. 



