CHAPTER XIX 
ELECTRICITY—RADIUM,., N-, AND X-RAYS 
OF late years our knowledge of the world’s working 
has been raised to another new and more advanced 
level both by the discovery of radium-rays and other 
mysterious emanations, and by a more practical 
acquaintance with electrical engineering. 
Unfortunately this is not a time in which it is at all 
safe to speak of these discoveries, for, like people who 
are a little out of breath from climbing to the top of a 
mountain ridge, our pioneers are not yet agreed as to 
the meaning of the new scenery, nor as to how it fits 
in with our older maps of the country. 
The exact nature of electricity is still a mystery, and 
this of course prevents any satisfactory explanation 
of its effects, 
It has been shown that the electrical potential of 
the atmosphere increases with the height above the 
earth, When rain falls, the electric potential of the 
earth becomes very much greater. At the tower of 
Meudon, near Paris, heavy rain increased the electric 
potential, which was from 600 to 800 volts, to as much 
as 12,000 to 15,000 volts,* 
So it is supposed that the subsoil water of the earth 
must have ahigh electric potential, perhaps giving rise 
to the mysterious earth-currents which affect our tele- 
phones. If that is so, one would expect feeble electric 
currents to be passing up living plants from the root 
* Compare ‘ Electricity of To-day.” 
Zit 
