Intelligence and Miscellaneous Articles. 495 



it explains naturally the abundant falls of rain or snow which have 

 always been noticed during the polar auroras. 



8. The sound that accompanies these experiments corresponds 

 to that which has often been heard during the aurora when the 

 distance was relatively small ; it is due to the vaporization pro- 

 duced by the electric trails of fire penetrating a liquid mass. 



9. The magnetic perturbations caused by the auroras are repro- 

 duced in these experiments, on placing a magnetized needle near 

 the circuit. The deviation increases or diminishes as the luminous 

 arc becomes more or less developed in the liquid. 



10. It follows, further, from these facts that the aurora must 

 be produced by a flow of positive electricity ; for the luminous phe- 

 nomena are the same as those at the positive electrode in the volta- 

 meter, and the negative electrode exhibits nothing similar. 



11. But are the polar auroras a discharge between the positive 

 electricity of the atmosphere and that of the earth supposed nega- 

 tive ? If they were so, we ought to observe very frequent falls of 

 lightning at the poles, or gleams or luminous tufts on the project- 

 ing parts of the ground, forming the counterpart of the phenome- 

 non that takes place in the air. Now observation shows that such 

 is not the case. I am therefore inclined to think that it is the im- 

 perfect vacuum of the upper regions that, acting as an immense 

 conductive envelope, plays the part of the negative electrode in the 

 above experiments, and that the positive electricity flows off towards 

 the planetary spaces, and not to the earth, through the icy mists 

 or clouds which float above the poles. 



12. As to the origin of this polar electricity, it has been assumed 

 that it comes from the equator and the tropical regions. But it 

 may be objected that the electrified clouds must discharge them- 

 selves during so long a journey ; and, in fact, we know that tem- 

 pests are rarer and rarer in proportion as we get nearer the poles. 

 My previous experiments, and others not yet published, having led 

 me to consider the heavenly bodies charged with positive electricity 

 (perhaps the only sort that exists), I should be inclined to regard 

 the earth itself as charged with positive electricity, which is libe- 

 rated from the land and sea by simple emission, radiated from the 

 whole surface, at the poles as at the equator, producing very dif- 

 ferent effects in the atmosphere in consequence of the diametrically 

 opposite meteorological conditions of these regions. 



Admitting this last hypothesis, one might conclude that the 

 aurora results from the diffusion in the upper strata of the atmo- 

 sphere, around the magnetic poles, of the positive electricity ema- 

 nating from the polar regions themselves, either in obscure radia- 

 tions when no obstacle is interposed, or converted into heat 

 and light by meeting with aqueous masses in the solid or liquid 

 state, which it vaporizes with a noise, and reprecipitates in the form 

 of rain or snow at the surface of the globe. — Comptes Rendus de 

 VAcademie des Sciences, vol. lxxxii. pp. 626-629. 



