WISLIZENUS ATMOSPHERIC ELECTRICITY. 13 



ematical calculation, may derive more plausibility from the 

 now established connection in the periodicity of terrestrial 

 magnetism and of the spots in the sun. Taking this ground, 

 atmospheric electricity may be ascribed directly to solar in- 

 fluence. Those, who seek for the source of atmospheric elec- 

 tricity in the atmosphere, itself explain its origin by the 

 many mechanical, chemical, and caloric changes going on 

 around us. Therefore, friction of the clouds and winds, 

 changes in the aggregate condition of matter, combustion, 

 vegetative processes on the surface of our globe, evaporation, 

 especially of sea-water, unequal distribution of temperature, 

 and, in consequence thereof, thermo-electric currents from the 

 equator to the poles, have been successively brought forward 

 and discussed as principal causes of atmospheric electricity. 

 It seems to me, that all these above named processes have 

 some influence on its distribution, modification, and, perhaps, 

 partial reproduction ; but I consider it very doubtful, if they 

 are really the instruments for creating atmospheric electricity 

 and filling the immense space of our atmosphere with its in- 

 exhaustible supply. But of all these supposed causes the 

 idea of thermo-electricity (adopted by Becquerel and de la 

 Rive) strikes me as the most plausible. The well-known 

 quality of the tourmalin to acquire electric polarity, when its 

 temperature is raised, and the physical experiment, made 

 with a bar of metal, heated on one end and cool at the other, 

 (in which case currents of electricity flow from the heated 

 to the cool end, the former being negative and the latter 

 positive,) prove certainly, that different states of electricity 

 will be produced and maintained by difference of tempera- 

 ture. It has been objected to this theory, that a column of air, 

 a nonconductor, cannot be compared to such a good conductor 

 as a bar of metal. But atmospheric air can only be called a 

 nonconductor when in a perfectly dry state ; and as it con- 

 tains constantly a greater or less proportion of that good 

 conductor, vapor, its relative conducting power cannot be 

 denied. 



Lastly, the prime source of atmospheric electricity has 

 been sought for in the globe itself. It is well known, that our 

 earth is not only the best conductor for both kinds of elec- 

 tricity, but also exhibits, on its surface, electricity that ap- 

 pears to be negative. It was, therefore, natural, that some 

 should regard our globe itself as the fountain-head of atmos- 

 pheric electricity, assuming that the electricity of the earth 

 passes to the atmosphere by induction. This theory has of 

 late been taken up again and ingeniously defended by the 

 learned Secretary of the Smithsonian Institution, Prof. J. 

 Henry. But as we know so very little of terrestrial electricity, 

 and, on the contrary, have acquired important information in 

 regard to the power of terrestrial magnetism, it may not be 



