232 POPULAR LECTURES AND ADDRESSES. 



on vacuum tubes seem rather to support the possi- 

 bility of that being the correct view if all spaec 

 were non-conducting, our atmosphere being a non- 

 conductor, and the rarer and rarer air above us 

 being a non-conductor, and the so-called vacuous 

 space, or the interplanetary space beyond that 

 (which we cannot admit to be really vacuous), 

 being a non-conductor also, then a charge could 

 be given to the earth as a whole, if there were 

 the other body to come and go away again, just 

 as a charge could be given to a pith-ball electrified 

 in the air of this room. Then, I say, all the phe- 

 nomena brought to light by atmospheric electro- 

 meters, which we observe on a fine day, would be 

 observed just as they arc. The ordinary observation 

 of atmospheric electricity would give just the result 

 that we obtain from it. The result that we obtain 

 every day of fair weather in ordinary observations 

 on atmospheric electricity is precisely the same 

 as if the earth were electrified negatively and the 

 air had no electricity in it whatever. 



I have asserted strongly that the lower regions 

 of the air arc negatively electrified. On what 



