EXPERIMENTS OF READ AND POUILLET. 313 



Mr. Read insulated a large hollow tin cone, with 

 many yards of small wire coiled up within it, 

 one end of which extended from the apex of 

 the cone, which was open, and was connected 

 with a sensible electrometer. Under this cone 

 was placed a vessel of water, the vapour from 

 which, on rising, was condensed and collected 

 by the cone and wire, when positive electricity 

 was produced, (which De Saussure could not 

 obtain without chemical action.) The same result 

 was obtained by burning different substances 

 under the cone. He maintained that the elec- 

 tricity which he derived from the atmosphere in 

 different degrees, at all seasons and times of the 

 day, was elicited from its vapour. He observed 

 that during the formation of thick fogs, elec- 

 tricity was abundant ; but scarce during their 

 solution and dispersion. (Spontaneous Electri- 

 city, p. 15.) He also found that his lightning 

 rod was less charged with electricity while im- 

 mediately under a cloud, than when at some 

 distance from it ; and that it acquired more 

 electricity before the rain commenced than 

 afterwards a fact which was also observed by 

 Beccaria. 



These beautiful and important experiments 

 will enable us to comprehend those of M. Pouil- 

 let, which he seems not to have rightly under- 

 stood himself. He placed a cylindrical piece 

 of charcoal in a vertical position, the top of 



