322 The Farmstead 



forthcoming — at least there is none which is 

 entirely satisfactory — but the facts are well 

 known. The mass of water- vapor which forms 

 the clouds becomes electrically charged just as a 

 rubber comb does when rubbed on the hair on 

 a dry day, or as an ebonite ruler does when 

 rubbed on a cat-skin. Perhaps by contact with 

 the air, which is in motion, the particles of 

 water become charged, and by the union of 

 multitudes of these the clouds are charged to a 

 tremendous pressure. Lightning can be pro- 

 duced artificially on a small scale by means of 

 electric machines, and the results of study of 

 these artificial discharges have been to show the 

 following facts : The air is not a conductor 

 of electricity, but when the electrical pres- 

 sure between two points becomes sufficiently 

 great the electric charge jumps suddenly be- 

 tween the two points at which the pressure 

 exists. It punctures a hole for itself through 

 the air. Lightning is the result. This dis- 

 charge is very violent, and it is accompanied 

 by a strong smell of ozone, which is only very 

 strong oxygen. If one were to examine the 

 points of the electric machine between which 

 the discharge took place, they might be found 

 either hot or cold, depending upon their size 

 and the material of which they were made. 

 Some materials offer more resistance to the 



