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" This is not a place in wliieli to renew the discussion that 

 has been started, regarding the actual source of atmospheric 

 electricity when the sky is clear, a phenomenon which has 

 been alternately ascribed to the evaporation of impure 

 liquids impregnated with earths and salts, to the growth oj 

 plants, or to some other chemical decomposition on the surface 

 of the earth, to the unequal distribution of heat in the strata 

 of the air, and finally, according to Peltier's intelligent re- 

 searches, to the agency of a constant charge of negative elec- 

 tricity in the terrestrial globe. Limiting itself, to the results 

 • yielded by the electrometric observations, such, for instance, 

 as are furnished by the ingenious electro-magnetic aparatus 

 first proposed by Colladon, the physical description of the 

 universe should merely notice the incontestable increase oj 

 the intensity of the general positive electricity of the atmosphere, 

 accompanied by an increase of altitude, and the absence of 

 trees, its daily variations, at its variations at different seasons 

 of the year, at different distances from the equator, and in the 

 (lifterent relations of continental and oceanic surface. The 

 electric equilibrium is less frequently disturbed where the 

 aerial ocean rests upon a liquid base, than ichere it impends 

 over land, and it is very striking to observe how in exten- 

 sive seas, small insular groups, efl:ect the condition of the 

 atmosphere and occasion the formations of storms, &c." 



" The term climate, in its most general sense, indicates 

 all the changes in the atmosphere, which sensibly effect 

 our organs, as temperature, humidity, variations of the baro- 

 metrical pressure, the calm state of the air, the action of 

 opposite winds, thQ amount of electric tension, the purity of 

 the atmosphere, or its admixture with more or less gaseous ex- 

 halations, and, finally, the degree of ordinary transparency 

 and clearness of the sky, which is not only important with 

 respect to the increased radiation from the eartli, the organic 

 development of plants, and the ripening of fruits, but also 

 in reference to the feelings and mental condition of man,'" 

 <* The processes of the absorption of light, liberation of 



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