No. Ill ] Dr. RICHARDSON ON THE AURORA. 621 



masses of light in other parts of the sky. The best defined part of the circle 

 was in the N.E. quarter, and here a quick lateral motion to and fro was pro- 

 duced, as if by its separation into perpendicular bars. It was about 8° broad 

 at this place, During the continuance of this phenomenon, many beams of 

 light rose perpendicularly from the upper margin of the circle, but before they 

 reached the zenith, their extremities were bent from their course so as to make 

 various curves side-ways, or even to appear as if rolled up upon themselves. 



When the Aurora had exhibited itself in this form for a considerable space 

 of time, the whole mass of light suddenly appeared in motion, and sweeping 

 round on each side, was gathered together to the southward of the zenith. 

 Immediately thereafter a large portion of it was seen in the S.E., assuming an 

 exact resemblance to a curtain suspended in a circular form in the air, and 

 hanging perpendicularly to the earth's surface. The lower edge of this curtain 

 was very luminous, and had a waving motion ; and the illusion was farther 

 heightened by the momentary appearance of perpendicular dark lines or 

 breaks in the light, in rapid succession round the circle, exactly as the waving 

 of a curtain would cause the dark shades of its folds to move along it. This 

 beautiful curtain of light was about 40° high, of a pale-yellowish colour, and 

 sent forth on the one side a process which approached the S.E. b. E. point of 

 the horizon, and on the other was connected with a long regular arch, termi- 

 nating in the N.W. horizon, similarly constructed, and having the same waving 

 motion with the curtain itself. All this time the sky was perfectly clear ex- 

 cept in the southern quarter, which to the height of 4° or 5° was occupied by 

 dark clouds, apparently intermediate between stratus and cirro-stratus. 



Half an hour after its first appearance, this curtain-formed Aurora was re- 

 solved into a number of detached irregular portions, which sometimes increased 

 rapidly in every direction until they met with other masses, either before ex- 

 isting or appearing at the instant, and formed an uniform sheet of light which 

 covered the whole sky. The formation of this great sheet of light was so rapid, 

 that the eye could only trace its progress partially, and its dissolution and re- 

 appearance were equally sudden. 



At 2h. p. m., the moon arose. A clear sky. The Aurora fainter and farther 

 to the southward than before. 



