24!2 



ON THE ELECTRIC COLUMN. 



Li-'htuine. ^^ '* coramoaly supposed, that the electric Jiuid, which, 



* under the form of lightnings darts from certain clouds, ex- 



isted previously in them, ready to be (discharged, at a pro- 

 per distance, on bodies which possess less of this Jluid, 

 either other clouds or the ground. On this idea, not impro- 

 bable at first sight. Dr. Franklin founded his invention of 



Conductors, pointed conductors elevated above houses, in hopes to preserve 

 the latter from being struck by thunder bolts. With the 

 above supposition, this method of security was very inge- 

 nious; for, if the electric fluid were actually accumulated 

 in a cloudy ready to be discharged on the first part of the 

 ground sufficiently elevated, ^ pointed conductor might dis- 

 charge that cloud without a spark, as it does the prime con- 

 ductor of an electric machine. But those who have fre- 



The electric q^igntlv travelled oh high mountains know certainly, that 

 fluid not accu- t J *= ,. 



Ululated in a there IS no analogy between a thunder cloud, and an znsw 

 thunder cJoud. ^^^^^ j^^^ ^^ which electric fluid has been accumulated. 



A cloud is a mere thxckfog, and thus such a completely 

 conducting medium, that the most powerful electric ma- 

 ehine worked in it could not, for an instant, accumulate 

 the electric fluid on its prime conductor ; it would be con- 

 stantly diffused through that moist air, and lost in the sur- 

 rounding bodies. This cannot be doubted ; but it is sup- 

 posed, that clouds, being surrounded by pure air, and thus 

 insulated, can retain the electric fluid accumulated in them 

 by whatever cause. In this consists the illusion, dissipated 

 by what is observed on mountains. I have frequently been 

 in valleys of the Alps, and of lower mountains, beset with 

 thunder clouds leaning on both sides against wet grounds, 

 and thus in so complete a conducting connexion with the 

 mountains themselves, that it was impossible any accumu- 

 lation of electric fluid could remain in the former; beside 

 which, no cause of such an accumulation has ever been ex- 

 plained: however flashes of lightning were emitted from 

 t|)ese clouds, with greater or smaller intervals, followed by 

 the astonishing phenomenon of the rolling of thunder ; and 

 to suppose this to be the repetition of one sound, by echoes 

 from cloud to cloud, is a fiction similar to that of poets ot 

 painters, who represent the gods as sitting on these fogs. 



Lightning 



