356 PHILOSOPHY OF STORMS. 



ble, is necessary, that the particles of vapor may have an 

 insulation necessary to produce the lowering of the cloud 

 down to the earth, without its making a discharge of the 

 electricity, whose attraction counterbalances the levity of 

 the cloud. It is necessary, also, that a rapid evaporation 

 should produce, in a little time, a considerable quantity of 

 electricity, and that there should be a very great calm in 

 the atmosphere to preserve it. 



These circumstances not being common beyond the trop- 

 ical heats, the spouts would be infinitely rare in our regions, 

 if a secondary cause did not come to determine the forma- 

 tion. This secondary cause is the presence of a cloud or a 

 group of clouds more elevated, possessing the same electri- 

 city as the inferior group. 



The action of the superior clouds, repelling the inferior 

 ones facilitates their descent, it will be sufficient that these 

 latter should have the constitution proper to preserve a 

 strong electric tension, and the conductibility there be very 

 feeble, that they may be drawn down to the very ground, 

 and thus form, the conducting and intermittent column, 

 which is called water spout. 



In fine, observations carefully made teach us that the 

 extremity of the cone extends or shortens itself according to 

 localities, that it balances and undulates, leaps from one 

 place to another, from one cluster of trees to another, and 

 abandons moist places, not without manifest resistance; 

 that in the centre is seen a canal, transparent, according to 

 some, luminous, according to others ; that in all there is 

 an intestine movement, here and there, sometimes direct, 

 sometimes giratory, varying without ceasing, and from one 

 portion to another, as we see in electrified smoke. Every 

 observer has expressed the impression which he experienced, 

 and in reality, when the approximation of the vapors to 

 the extremity of the cone is such, that there results a real 

 liquidity, this liquid and transparent medium remains sus- 



