50 METEOROLOGICAL 



first quarter. "Occasionally, as on the 7th January, 

 1831, printed characters could be read without 

 difficulty."" Indeed, the intensity of the Northern 

 or Polar light is sometimes very great ; and 

 Lowenorn assures us, that on the 29th June, 1786, 

 he recognized the coruscation (trembling motion) 

 of the Aurora Borealis in bright sunshine. 



Some splendid manifestations of the Aurora 

 Australisj or Southern light, were witnessed by 

 Captain J. Koss in his voyage to the South Pole.* 

 These Southern lights have often been seen in 

 England by Dalton, and Northern lights have been 

 witnessed in the Southern hemisphere 14th Ja- 

 nuary, 1831 as far as 45 degrees latitude. 



It has been shown, by many experiments, that 

 the electric light, whatever be its source, does not 

 show any signs of polarization. Now this has been 

 lately proved to be the case with the light of the 

 Aurora, which shows no polarization, according to 

 Mr. Rankine ; but when it is viewed reflected from 

 the surface of a river, polarization is detected, 

 which proves that in the former case the want 

 of polarization is not owing to the weakness of 

 the Aurora observed. 



A curious phenomenon was noted by Admiral 

 Wrangel, when he was on the Siberian coast of the 

 Polar Sea. He observed, that during an Aurora 



* The Aurora Australia was seen for the first time by Captain 

 Cook in his first voyage, and again in his second voyage. 



