METEOROLOGY AND ALLIED SUBJECTS. 



31i> 



IVIascart has i»ublislied the cfiscussion of the observations of atmos- 

 jiherie electricity, recorded every two aud a half minutes consecutively^ 

 since February, 1879, by means of the water-dropping ai)paratus aud 

 the electrometer of Sir William Thomson, as combined in the apparatus- 

 manufactured by Charpentier. The prevalence of the negative elec- 

 tricity in the rain clouds, followed by very strong positive electricity 

 after the raiu, appear to be important facts, as prominent in Paris as- 

 they are also kuown to be in England and Italy. 



The average diurnal periodicity expressed in arbitrary units is showA 

 by the following table: 



The minimum at 3 p. m., aud maximum at 9 p. m., as here shown, are- 

 quite at variance with observations of Quetelet, Denza, and Everett, 

 the reasons for which remain to be investigated. (Z. 0. G. M., XV^ 

 1880, p. 136.) 



Sophus Tromholt, of Norway, has published the first results of the 

 work undertaken by him with reference to auroras, which is nothing 

 less than a general formation of a system of aurora observations for 

 the whole of Korway, Sweden, and Denmark. The material accumu- 

 lated in the first witnter alone is so great that valuable results may be 

 drawn from it. In the first place, it ajipears that there is scarcely an 

 evening that one or more stations did not report auroras, although the 

 observations occur during the years of auroral minimum; hence the 

 author concludes that the afirora is a very local phenomenon and takes 

 place at a very small altitude above the earth's surface. The table that 

 shows the cases in which auroras are observed at auxiliary stations,, 

 without being observed at the central station, Bergen, affords the most 

 striking proof of the local character of the phenomenon. The follow- 

 ing table shows the relative frequency of auroras for the respective 

 zones of latitude : 



