240 Intelligence and Miscellaneous Articles. 



from it. The upper plate was lifted from its place by its glass 

 handle, and its electrical condition tested by a gold-leaf electrometer. 

 I have found it convenient first to compress the air and close the 

 stopcock, when the condenser would be found to be charged with 

 positive electricitj' ; then after discharging all traces of it both from 

 the condenser and the wire leading to it, the air was allowed to 

 escape, and the condenser would become recharged to an equal 

 extent. 



My experiments with this apparatus have extended over about 

 eight months, and I have found the action to bear a strong analogy 

 to that of the electrical machine. In damp or warm weather little 

 or no effect would be produced, whilst at other times, particularly in 

 clear cold weather, the action would be so strong as to diverge the 

 leaves of the electrometer to their utmost extent. In warm weather, 

 when no action would be produced, I have attained the result by 

 cooling the air artificially. A sudden expansion or contraction 

 always increases the effect. 



The results with oxygen gas were similar, but I was not success- 

 ful with either hydrogen or carbonic acid gases. 



It is believed that the results which have been obtained on a small 

 scale in my experiments may be traced in the great operations of 

 nature. The fluctuations of our atmosphere produce compressions 

 and expansions sufficient to cause great electrical disturbances. Par- 

 ticularly should this be observed in the dry cold regions of our atmo- 

 sphere above the effects of moisture and vapours ; and it was esta- 

 blished by the experiments of Becquerel as well as those of Gay- 

 Lussac and Biot, that the electricity of the atmosphere increases in 

 strength with the altitude. 



A manifest relation, moreover, between the electricity of the atmo- 

 sphere and the oscillations of the barometer has frequently been 

 observed. Humboldt, treating upon the subject in his ' Cosmos,' re- 

 marks, among other things, that the electricity of the atmosphere, 

 whether considered in the lower or the upper strata of the clouds in 

 its silent problematical diurnal course, or in the explosion of the 

 lightning and thunder of the tempest, appears to stand in a mani- 

 fold relation to the pressure of the atmosphere and its disturbances. 



The tidal movements of our atmosphere produce regular system- 

 atic compressions twice in twenty-four hours. These occur with so 

 much regularity within the tropics, as observed by Humboldt, that 

 the time of day is indicated within fifteen or twenty minutes by 

 the state of the barometer. And Saussure observed a diurnal change 

 in the electricity of the atmosphere corresponding with the diurnal 

 changes of the barometer. The electricity of the atmosphere, he 

 observes, has therefore a daily period like the sea, increasing and 

 decreasing twice in twenty-four hours. It, generally speaking, 

 reaches its maximum intensity a few hours after sunrise and sunset, 

 and descends again to its minimum before the rising and setting of 

 that luminary. 



Other phsenomena, which it is believed may be traced to the same 

 cause, willbe the subject of anothercommunication. — From Silliman's 

 American Journal for November 1857. 



