300 SCIENTIFIC RECORD FOR 1884. 



regions. Often barometric minima, formed on tlie edge of tlie greater 

 centers of depression, glide in rapid succession along tlie edge of the 

 great barometric maxima, exerting upon the wind and weather of the 

 region through which they pass in broad circles an extraordinary influ- 

 ence, and give the weather the character of variability. As a contribu- 

 tion to this subject, see my investigation on Typical Phenomena, which 

 I wrote at the beginning of the year 1883 for the introduction to the 

 volume of Monthly Weather Eeviews for 1882, and which will soon be 

 published in greater fullness in the Arcliiv of the Deutsche Seewarte- 

 In this investigation the effects of the depressions upon the weather are 

 referred back to the well established main tracks of storms, and these 

 are brought into connection with the general atmospheric conditions. 

 These and similar studies give the first foundation for weather predic- 

 tion for a long period in advance. We are persuaded that the weather 

 predictions for such periods are not among the impossibilities, but that 

 hereafter they will at some time exceed in usefulness the daily predic- 

 tion." {D. M. Z., I, pp. 22-70.) 



328. [Predictions three and four days in advance based on similar 

 considerations were made bj' the Signal Office in 1871 and 1872 on 

 occasions of imjiortance.] 



X. — (a) Atmospheric electricity; Lightning; (&) Terrestrial 



MAGNETISM; (c) GROUND CURRENTS; [d) AURORAS. 



329. The subject of atmospheric electricity and terrestrial earth cur- 

 rents was dealt with by the Electrical Congress held at Paris April, 

 1884, which recommended that the different countries should collect 

 reports and forward them annually to the International Bureau of Tel- 

 graph Administration at Berne, which bureau will digest and commu- 

 nicate a summary in return. It also recommended that observations 

 of earth currents be made in all countries. 



330. The United States National Conference of Electricians, meeting 

 at Philadelphia in 1884, renewed these recommendations, commending 

 them most heartilv to the action of our Government, and appointing a 

 committee to confer with the Chief Signal Officer, who is commissioned 

 to collect the data for the United States, and who has already for two 

 years been conducting preliminary observations on atmospheric elec- 

 tricity with a view to the addition of this item to the Signal Service 

 daily report. 



331. E. Hoppe publishes a history of electricity (Leipsic, 1884). This 

 volume of C22 pages shows great industry on the part of the author, 

 who has probably made his work quite as exhaustive as would be profit- 

 able to the most patient reader. He divides the progress in this science 

 into the following epochs : (1) Before Franklin ; (2) Franklin and Cou- 

 lomb; (3) from Volta to 1819; (4) electricity and magnetism; (5) from 

 Ohm to Helmholtz ; (G) more recent progress. (D. M. Z., i, p. 419.) 



332. Prof. P. G. Tait, of Glasgow, in a lecture before the Scottish 



