F. Dellmann on Atmospheric Electricity. 

 October 21. 



419 



At6-0OA.M 155-1 



At7-50A.M 265-6 



November 15. 



At 



6-00 A.M. 



7-16 „ , 

 10 00 „ , 

 12-00 „ . 



300-8 



595-4 (sudden thick mist). 



370-5 (mist still thick). 



0-0 (mist almost disappeared). 



The following are examples of the variation at sunset : — 



These numbers also agree with Schiibler's remarks on the daily 

 variation. The daily variation is seldom regular, though, of 

 course, it is most so when all other aerial phjenomena manifest 

 regularity, and therefore in fine weather; this is sometimes the 

 case even when the daily barometrical variations arc perceptible. 

 This was the case here in February 1851, when for 40 hours 

 hourly observations were made, and during 34 hours the varia- 

 tions were plainly perceptible. 



A few words in conclusion on the origin of atmospheric elec- 

 tricity. In a letter to Quetelet, which this celebrated philo- 

 sopher afterwards published, Peltier, jun. first expressed the 

 opinion that, originally, the electricity of the air is the earth's 

 electricity conducted into the electrometer through the observer ; 

 and this same opinion, according to which the air has no elec- 

 tricity whatever, was assented to by Dr. Lament*. Peltier's 

 reasons for this assertion were deduced from the numbers obtained 

 in the Brussels observations, and arc no longer valid, siuce Que- 

 telet, ia consequence of later observations, considerably altered 

 those numbers in subsequent communications. These same rea- 

 sons are still less in accordance with the results obtained by 

 Schiibler in Munich and in Kreutznach. The passage of elec- 

 tricity through the ob.server into the measuring instrument or 

 into the collecting sphere is not a fact, but a pure hypothesis. 



* Poggcudorff' s Annalen, vol. l.\xxv, p. 500. 

 2E 3 



