ELECTRICITY DURING RAIN. 469 



changing the kind of electricity. There must, of course, be the zero of 

 tension, which occurs in solid and isolated conductors submitted to the 

 electricity of influence, as it is now commonly termed in the schools, 

 and I should say this zero of tension was immersed in the ethereal space 

 electrified with the same electricity with which the body existiug at the 

 center was invested. I invite physicists to repeat my experiments, since 

 by them may be overthrown the doctrine of atmospheric electricity of 

 influence in the air ; and, still more, the law, enunciated by Signor Luigi 

 Palmieri, and confirmed by Padre A. Secchi, regarding the negative circle 

 which surrounds the cloud that is being resolved into rain, snow, or 

 hail. 



ON THE PRESENCE OP ELECTRICITY DURING THE FALL OF RAIN. 



By Pkof. PAI.JIIERI, OF THE VESUVIUS Observatory. 



[Trayislatcd for the Smithsonian Institution.] 



All the observations upon atmospherical electricity made during 

 storms before 1850, the date of my first memoir upon electrical mete- 

 orology, had established the presence of electricity of greater or less 

 tensions — alternately positive and negative — and consequently neutral 

 during its passage from one phase to the other. During the fall of rain 

 in calm weather electricity had been observed to be sometimes positive, 

 sometimes negative; and many authors, as Kiimtz, were induced to dis- 

 tinguish positive ami negative vdins. Quetelet alone had observed that 

 during the same fall of rain there might be positive aud also negative 

 electricity. During this confusion I found, in 1853, a very simi)le law 

 that determines electrical manifestations during the fall of rain, hail, or 

 snow; having been enabled to discover it, thanks to a movable conductor 

 and to the possibility of placing it on the Vesuvius Observatory, G37 

 meters above the level of the sea, and under the clear atmosphere of 

 Naples, through which objects can be seen at a great distance. This 

 law can be expressed thus: When rain falls there is a considerable devel- 

 opment of positive electricity^ to itli a zone or ivave of negative electricity, 

 folloived by another of strongly positive electricity. 



The breadth of the zones depends upon the extensiveness of the show- 

 ers, aud also upon the conditions of the air surrounding the clouds that 

 resolve themselves into water. The course foUow^ed by the rain while 

 falling through a more or less extensive space, according to the direction 

 of winds, gives the observer an opportunity to note the passage from one 

 phase to another ; and if rain was falling on a given point with the same 

 intensity, and without change of direction, the observer would have con- 

 tinually the same phase. The breadth of the zones alters rapidly during 

 the appearance of lightning, and then soon returns to its previous state. 

 Any variation in the intensity and extensiveness of the showers causes 

 changes in the breadth of the zones, and therefore the observer is easily 



