76 Intelligence and Miscellaneous Articles. 



in the morning fog is due to the sun not having as yet acted on 

 the fog. The author adduces a table of Quetelet, which shows as 

 the result of many years' observations that the monthly mean of 

 the strength of atmospheric electricity is the less, the greater is 

 the monthly mean of the solar radiations measured with the actino- 

 meter. 



The author explains in the well-known manner the formation of 

 the high tensions observed in storms. As the first condition in the 

 original charge of the drops is the solar radiation, thunderstorms 

 are in causal connexion with this, and are most frequent in hot 

 countries in summer, and in the afternoon. That the maximum 

 daily occurrence of thunderstorms is somewhat behind that of the 

 solar radiation is ascribed by the author to the time required for 

 the charge and for the coalescence of the individual drops. The 

 other meteorological phenomena which accompany the storms are 

 considered by the author to be secondary. The more infrequent 

 whirlwind storms, which, in contradistinction to the heat-storms, 

 occur mostly in winter, and at night, and which cannot be explained 

 on the above principles, were supposed to be brought from more 

 southern regions. 



The author finds a further support for his theory in the course 

 of the yearly and of the daily periods of atmospheric electricity. 

 The yearly period, with its winter maximum and summer mini- 

 mum, would directly correspond to the influence mentioned. The 

 daily period is more complicated, for it exhibits two maxima 

 and two minima. But this may also be explained, if to the influ- 

 ence of the solar radiation the influence be added which must be 

 exerted by the ascending motion of the negative clouds at daytime 

 and the descent at night-time. The author observes that Exner's 

 theory, according to which aqueous vapour is the carrier of nega- 

 tive electricity, is quite in disaccordance with the facts of the daily 

 period of atmospheric electricity. 



In conclusion the author develops the result that, since the 

 greater part of the active solar radiation is absorbed in the upper 

 regions, these must conduct far better than the lower layers of air. 

 Now since these upper layers of air are moving strongly from west 

 to east round the earth, a conductor would be obtained under the 

 influence of the sun's rays, which rotated about a magnet (the 

 earth) : by unipolar induction electromotive forces must be set up 

 which would drive the electricity in the higher atmosphere from 

 the equator to the pole. The auroras boreales and the daily varia- 

 tions of terrestrial magnetism would be referred to these phe- 

 nomena. The author observes that Schuster and Balfour Stewart 

 had already assumed an increase of the electrical conducting power 

 of the air with the sun's rays ; they, how T ever, had sought for the 

 cause in a heating of the layers of air, an hypothesis the improba- 

 bility of which had already been demonstrated by Hann. — Meteor. 

 ZeitscTirift, vol. v. p. 297 (1888) ; BeiU'dtter der PhysiJc, vol. xiii. 

 p. 328. 



