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the key to the appearance of that darkness in the sky 

 to the far North which I have mentioned as an invariable 

 accompaniment of the Northern Lights. The shining, 

 beginning sometimes from the 65-th degree of latitude, 

 can of course develop waves only towards the North. 



2; We saw that the Aurora Borealis produces a di- 

 sturbing effect upon the magnetic needle. The oxygen 

 as I said coming in contact with the atmosphere produces 

 friction, which in its turn produces light through com- 

 bustion of part of the oxygen. But combustion of oxygen 

 is always accompanied by electrical agitations, and there- 

 fore the movement of the magnetic needle is a natural 

 consequence of the Northern Lights. 



3) That this phenomenon is accompanied under cer- 

 tain conditions by audible sound is a circumstance which 

 every gust of wind adequately explains. The lightest 

 zephyr buzzes in our ear; but here we have to do with 

 colossal movements of oxygen over our atmosphere low- 

 ering that atmosphere by its mass so far that the sound 

 waves of its friction reach the surface of the earth. 



4) After the appearance of the Northern Lights the 

 horizon is always covered with feathery clouds. The 

 cause of this is the release of that quantity of hydrogen 

 which was combined with the combusted oxygen : this 

 hydrogen as we have seen floats in space in feathery 

 forms. 



Thus all the details of this phenomenon are readily 

 and simply explicable after all by the plain laws of 

 physics. It is altogether unnecessary to seek some my- 

 stery - - some unknown, volcanic polar force. Travellers 

 who set out in search of such, are risking their life in 

 a wild goose chase as the Southern Lights show, seeing 

 that in this case the direction of the light waves is the 

 same, whereas were their origin volcanic their direction 

 would be opposite. The common course of both Sou- 

 thern and Northern Lights is owing to the fact that the 

 earth's orbit lies in front of the orbit of solar movement 

 and not on the same plane : both poles therefore conduct 



