182 ELEMENTS OF STATIC ELECTRICITY. 



a charged Leyden jar. Now since a constant difference 

 of potential is proved to exist between the earth's 

 surface and the atmosphere, and between upper and 

 lower atmospheric strata, we must conclude that 

 ascending and descending currents result from this 

 difference : and that the clouds, and the invisible vapor 

 diffused through the air, are, like the air, subject to this 

 constant electric movement. But, there being also a 

 horizontal movement, due to the winds, the resultant 

 of the two movements is a series of curves, ascending 

 and descending, as the body of air and vapor moves 

 over areas of high or low potential. 



The air and vapor in contact with the earth, becom- 

 ing electrified to the same potential as the earth's sur- 

 face, are repelled, and attracted upward by the force 

 resulting from difference of potential in the stratum of 

 least resistance above. Similarly the air and vapor 

 above are repelled, and attracted downward in conse- 

 quence of the difference of potential below. 



The morning and evening maxima, occurring at 

 opposite points in the rational horizon, show that two 

 electric waves traverse the surface daily from east to 

 west, as the earth revolves from west to east. And, at 

 points about equally distant from these waves, follow 

 the two daily minima. During the maxima the ascend- 

 ing and descending currents must acquire a great 

 increase, both in volume and in acceleration of move- 

 ment: while the minima, preceding and following, 

 create horizontal movements between the areas of high 

 and low potential ; producing resultant curves, similar 

 to those due to the winds, but recurring in regular 

 succession. In fact these currents are themselves 

 electric winds. 



