354 PHILOSOPHY OF STORMS. 



preaches the earth, a quantity depending on its specific 

 gravity, and on the square of the accumulated charge. 

 Having arrived at a certain distance, the attraction of the 

 two electricities preponderates over the resistance of the air ; 

 a discharge takes place, the cloud rises, until a new com- 

 munication of electricity takes place, producing an equal 

 state and an equal result. The electric change, as we see, 

 is made between the atmospheres which surround the bodies, 

 it is the positive and exterior quantities of the cloud, which 

 are neutralized, with an equal portion of negative and ex- 

 terior electricity of the soil. But the sphere of electricity, 

 which surrounds, is not formed by all the electricity which 

 it contains, as that of a globe of metal, which does not hold 

 any portion in its interior; it is, on the contrary, often only 

 a very small portion of the whole, a portion which is de- 

 pendent on the interior reactions and conductibility. A 

 cloud being composed of a multitude of distinct bodies, of 

 particules of vapor called vesicular, each of these vesicules 

 has its electric sphere, which is inherent in it; according to 

 their proximity, or, what amounts to the same thing, ac- 

 cording to the density of the cloud, the reaction of these 

 spheres, the one on the other, repels to the periphery a part 

 of their electricity until the exterior reaction is equal to 

 the interior reactions. This exterior quantity will be so 

 much the smaller as the insulation of the particles of vapor 

 is more perfect. 



If the insulation is great, if the radiation towards the 

 periphery is weak, there will result a great tension, and 

 consequently a great attraction, which will bring the clouds 

 near the ground, without producing a discharge sufficient 

 to render the specific levity of the cloud predominant. It 

 is to this weak exterior reaction, that we must refer the 

 division of one spout into several. 



When the periphery possesses a sufficient quantity of free 

 electricity, which acts by repulsion, on all the electricities, 



