1 68 Mr.W. R. Bin on the connexion of Atmospheric Electricity 



an electric discharge may take place. 2nd. Mr. Howard also 

 regards the descending body of rain as a conducting medium: 

 he says, " the whole aggregate of floating, uniting, and falling 

 drops from the very summit of the cloud to the ground, may 

 form one immense conductor." He further remarks: "On 

 the supposition that a sudden local shower is an atmosphe- 

 rical CONDUCTOR WITH ITS FOOT ON THE EARTH, we are 

 able to assign a satisfactory origin and use to the spreading 

 crown, which is frequently seen above it, and in which we 

 may discern an arrangement, tending from every side towards 

 the dense part where the rain is formed, in a manner not re- 

 quired by the simple law of gravity. These rectilinear or 

 hairy portions are the collecting points of the conductor formed 

 in the positive haze in consequence of the destruction of the 

 equilibrium [of its charge], which necessarily gives rise to a 

 flow of the electricity towards the conductor." 



Upon reviewing the successive steps in the development of 

 cloud and rain, from the first formation of the minute water 

 particle with its feeble electric charge^ to the torrent-pouring 

 nimbus with its violent electric discharge, we have particularly 

 to trace the formation of this cloud in a portion of atmosphere 

 bounded above by a sheet of cirrostratus positively electrified, 

 which rests on a stratum of air negatively electrified, this ne- 

 gative state being ifiduced by the action of the positive cirro- 

 stratus, which at this time is highly charged and ready to pre- 

 cipitate, the clouds below being negatively electrified by in- 

 duction. The atmospheric conductors are also at this time 

 negatively electrified, in common with other bodies on or near 

 the earth. This (according to Howard's remarks) appears to 

 be the moment when the nimbus is formed ; the disturbance, 

 which had been produced ve^y gradually, now makes itself di- 

 stinctly felt ; the masses of cumulus, originally positive, by the 

 superior energy of the cirrostratus, are more or less thrown 

 into a negative state ; electrical attraction between the cirro- 

 stratus and cumulus rapidly takes place, and is accompanied 

 by the agglomeration of the minute particles of water forming 

 the clouds; rain immediately descends, which, if the electric 

 tension either of the cloud or of the descending rain-drops is 

 not too intense, becomes a conducting medium, and opens an 

 electrical communication with the earth j but if the charge of 

 the cloud, on the other hand, becomes so high as to result in 

 a violent detonation, either before or coincident with the for- 

 mation of rain, or the rain-drops themselves are incapable of 

 I'etaining the charge received by them at the time of their for- 

 mation, then we have with the nimbus all the phaenomena of 

 a thunder-shower. 



