494 Intelligence and Miscellaneous Articles. 



rapidly folding and refolding upon itself (fig. 3). This undulatory 

 motion perfectly resembles that which, in the aurora, has been com- 



Ffc. 8. 



pared to the bending and wriggling of a serpent or the undulations 

 of drapery agitated by the wind. 



2. Although, in consequence of the employment of salt water, 

 yellow light predominates in these experiments, purple and violet 

 tints similar to those of the aurora are also observed at the parts 

 where the water from the condensed vapour is less charged with 

 salt. 



3. The rays of the luminous arc arise from the penetration of the 

 electric flow into the liquid ; and as the resulting vacuum is filled 

 up, new rays are formed : thus we explain how it is that the jets 

 of light of the aurora dcwt, or appear to be momently shot forth and 

 renewed. 



4. The dark circle or segment formed in the aurora by the mist 

 or nebulous veil encountered by the electric flow corresponds to the 

 humid circle or segment which, in the experiment, surrounds the 

 electrode, and around which the voltaic current spreads. 



5. The form of an arc in the voltameter results from the liquid 

 not entirely surrounding the electrode ; but if more of the wire be 

 immersed, luminous waves or entire circles are produced, the same 

 as in the auroras — of which the arc is often considered to be the 

 portion visible to the observer, of a complete luminous circle. 



6. The liquid is violently agitated by the electric blast ; luminous 

 vortices and rings are produced by the shock of the electrified waves 

 against one another ; and, finally, if the operation is conducted 

 with only a small quantity of liquid, a luminous ebullition is pro- 

 duced corresponding to that fluctuation of light which also charac- 

 terizes the polar auroras. 



7. The deeper the electrode penetrates into the liquid, the more 

 briskly and abundantly is aqueous vapour liberated. This pheno- 

 menon, of which the most powerful batteries of static electricity 

 hardly afford a suspicion, is important for consideration, because 



