'J32 METEORS. 



the electricity's descending with that snow, to enter the 

 earth. It may therefore be accumulated on the ice. 

 The atmosphere being heavier in the polar regions than 

 in the equatorial, will there be lower, as well from that 

 cause as from the smaller effect of the centrifugal 

 force ; consequently the distance of the vacuum above 

 the lower part of the atmosphere will be less at the poles 

 than elsewhere, and much less than the distance (upon 

 the surface of the globe,) extending from the poles to 

 those latitudes in which the earth is so thawed as to 

 receive and imbibe electricity. May not then the great 

 quantity of electricity brought into the polar regions by 

 the clouds which are condensed there, and fall in snow, 

 which electricity would enter the earth, but cannot pene- 

 trate the ice ; may it not, as a bottle overcharged, break 

 through that low atmosphere, and run along in the 

 vacuum over the air towards the equator ; diverging as 

 the degrees of longitude enlarge, strongly visible when 

 densest, and becoming less visible as it more diverges ; 

 till it finds a passage to the earth in more temperate 

 climates or is mingled with the upper air ? If such an 

 operation of nature were really performed, would it not 

 give all the appearances of an Aurora Boreal is ? And 

 would not the Auroras become more frequent after the 

 approach of winter ; not only because more visible in 

 longer nights, but also because in summer the long pres- 

 ence of the sun may soften the surface of the great ice 

 cake, and render it a conductor by which the accumula- 

 tion of electricity in the polar regions will be pre- 

 vented T 



This theory is confirmed by the fact that if you ex- 

 haust a glass vessel of the air, and then charge it with 

 electricity, the electric fluid in the vacuum exhibits all 

 the appearances of the Aurora Borealis. When the ves- 

 sel is most perfectly exhausted, the electric fluid appears 

 quite white ; when a little air is introduced, it assumes 

 more of a purple hue. 



At different periods of the world, and in various coun- 

 tries, there have been brilliant illuminations of the 

 heavens, resembling fiery arches, and clouds, and flaming 



