WISLIZENUS — ATMOSPHERIC ELECTRICITY. 529 



that the generally prevailing electricity is positive, and only 

 exceptionally negative, and that a certain periodicity exists 

 in the prevailing positive electricity. Atmospheric electri- 

 city is therefore "one of the regular phenomena in our atmos- 

 phere, and ought to be as regularly and carefully observed as 

 barometric pressure, temperature, humidity, etc. By daily 

 regular observations only of meteorological phenomena, con- 

 tinued for many years and extended over the whole globe, 

 are we enabled to discover their complicated laws and to 

 draw from them conclusions useful to mankind. 



The zeal with which atmospheric electricity was explored 

 in the last century gradually cooled off on account of the 

 many difficulties met with in these researches. The ethereal 

 nature of the so-called electric fluid, the want of very deli- 

 cate instruments, the danger, even, complicated sometimes 

 with such observations, deterred physicists from observing 

 atmospheric electricity as regularly <is other meteorological 

 phenomena. But within the last fifteen years its explora- 

 tion has been taken up again in Europe with renewed zeal 

 and with improved instruments, and regular electrical obser- 

 vations form now an important part of meteorology. In the 

 United States and, as far as I know, on the whole continent, 

 no observations of the kind were made. I concluded there- 

 fore to supplant this want in our meteorological records, and 

 procured myself for that purpose one of the most delicate and 

 reliable modern instruments, the electrometer of Prof. Dell- 

 man, by which the quality as well as quantity of observed 

 electricity can be determined and measured. This instru- 

 ment is a so-called torsion balance, the essential part of which 

 is a very fine glass thread, suspended vertically, to the lower 

 end of which a very light metallic beam is horizontally at- 

 tached, moving above another beam, which is fixed. When, 

 by means of a metallic ball, the electricity is collected in the 

 atmosphere and transferred to the two beams, both are load- 

 ed with the same electricity, and since equal electricities 

 repel each other, the upper movable beam will be repelled 

 and turn around a circle, divided into degrees, more or less 

 according to the electric charge. 



For the last seven years I have made uninterrupted daily 

 observations with this instrument, the numerical result of 

 which is contained in the foregoing tables, to which, for bet- 

 ter understanding, I will yet add some remarks. 



There are flowing through our atmosphere constant cur- 

 rents of electricity, the equilibrium of which is so easily dis- 

 turbed that they will accumulate often at one point and cause 

 a vacuum at another. 



The electricity prevailing in the usual undisturbed state of 

 atmosphere is positive. 



In thunderstorms atmospheric electricity is generally 



