No. III.] 



APPEARANCES OF THE AURORA. 



559 



February 13th, the atmosphere was so dense this night, that the stars were 

 completely obscured, and the edges of the moon could only be faintly traced 

 through the haze. At nine p. m., there was not any appearance of the 

 Aurora, and the needle rested at 348° 30', its usual position at this hour, 

 when undisturbed by the Aurora. At 11° 30', faint streams of light gleamed 

 through a large portion of the heavens, both in the zenith and near the hori- 

 zon, and immediately afterwards brilliant coruscations burst forth of the 

 most agitated kind. At llh. 40', a horizontal stream extended from 279° 

 to 31°, and the interior motion, similar to rolling smoke, passed from the first 

 point to the latter. The needle was now drawn 3° 30' to the eastward, or 

 as far as 345° 00'. At llh. 50', there appeared another stream of irregular 

 shape, which proceeded from 279° in a line nearly parallel to the horizon, until it 

 curled round at 9°, or near the direction of the magnetic meridian. The interior 

 motion flashed along this stream with the utmost rapidity. The needle moved 

 now to 343° 50', or 4° 40' eastward of its first position. And during the appear- 

 ance of this coruscation, I perceived the needle to oscillate between 343° 

 50', and 344° 40' ; and it may be remarked this was the only occasion on which 

 a vibratory motion was observed. On the disappearance of this display, bril- 

 liant semicircular curves were presented in the same quarter, ornamented with 

 all the prismatic colours. At llh, 55m., the needle had receded westward as 

 far as 347° 00'. The important fact of the existence of the Aurora, at a less 

 elevation than that of dense clouds, was evinced on two or three occasions this 

 night, and particularly at llh. 50m., when a brilliant mass of light, variegated 

 with the prismatic colours, passed between an uniform steady dense cloud and 

 the earth ; and, in its progress, completely concealed that portion of the cloud 

 which the stream of light covered, until the coruscation had passed over it, 

 when the cloud appeared as before. 



The observations of this evening seem to corroborate the remark which I had 

 previously made— that the direction in which the needle moves, appears to 

 depend on the position in which the streams of Aurora are placed, and the 

 quantity of the effect upon its proximity to, or distance from, the earth. When 

 the extremities of arches lay near the bearings of 234° and 54°, the needle 

 moved eastward ; and when near the bearings 324° and 144°, or 279° and 99°, 

 the motion of the needle was westward. Both of these facts were shewn to- 



