ON LUMIIilOUS PHENOMENA. gj 



ly fail to produce some other appearances, beside a tran- 

 sient illumination ; and more particularly with the extreme 

 velocity of the meteor of Aug, IS, which is three times as 

 •j^reat as a body falling from infinite space towards the Earth 

 ivould have acquired, when it came within 50 miles of the 

 Earth's surface. He therefore recurs to electricity, the only 

 agent in nature with which we are acquainted, that seems 

 capable of producing such phenomena. Its extreme and 

 liitherto unmeasured velocit}^ the electric phenomena at- 

 tending fire balls, the hissing noise, their connection with 

 and similarity to the northern lights, which have sometimes 

 assumed this form, and particularly their course, which is for 

 the most part nearly in the magnetic meridian, are among 

 the circumstances which are pointed out and elucidated in 

 a perspicuous and highly interesting manner. And he con- Conclusion, 

 eludes by observing, that if the conjectures he offers be 

 just, there are distinct regions allotted for the electrical 

 phenonjena of our atmosphere. Here below we have thun- 

 der and lightning, from the unequal distribution of the elec- 

 tric fluid among the clouds; in the loftier regions, whither 

 the clouds never reach, we have the various gradations of 

 falling stars ; till beyond the limits of our crepuscular at- 

 mosphere, the fluid is put into motion in sufficient masses to 

 hold a determined course, and exhibit the different appear- 

 ances of what we call fire balls; and probably at a still 

 greater elevation above the earth, the electricity accumulates 

 in a lighter less condensed form, to produce the wonder- 

 fully diversified streams and coruscations of the aurora bo- 

 realis. 



There is a fact observed by Mr.de Saussure, which seems 

 difficult to be accounted for by the help of our present 

 knowledge of electricity. He was on the Alps with some 

 friends, while a thunder storm formed in the air beneath 

 them. While it lightened and thundered below, they found 

 themselves electriHed, but differently, so that they drew 

 sparks from each other *. 



I shall finish this communication by a remark of Mr. A south wind 

 Winn on the aurora borealisf, that this phenomenon is ^^1.'^'^'^^.^^];^:^"" 



* Memoirs of the Academy of Sciences for 1770. 

 t Ph. Trans, vol, 64, p. 1^8. 



usually 



