On the Variation of the Magnetic Needle. 



231 



quarter before three, a most brilliant streamer 10° in breadth, ex- 

 tending up to ^ and 7 Ursse Minoris. Cloud stretching along on 

 the horizon, with an arch of light extending all along upon the 

 cloud. At five minutes before three, the streamers all moved to the 

 east, about 6°. Highest extends up a little above 7 Ursas Minoris. 

 This aurora was seen by Mr. E. C. Herrick, between Philadelphia 

 and New York, from half past twelve to three o'clock. It appear- 

 ed a little to the west of north ; a low arch about three degrees high 

 resting upon a cloud ; beams shot up about 30° high ; moved lat- 

 erally to east ; brightest between two and three o'clock, when at 

 South Amboy, N. J. Produced a very sensible illumination of the 

 village. 



This was the most remarkable aurora I have ever witnessed, and 

 the most remarkable disturbance of the magnetic needle, the entire' 

 range being 1° 41'. A particular account of the appearances, has. 

 been given in this Journal, Vol. xxix, p. 388. The needle was 

 little, if at all affected by the auroral arch which appeared during the 

 forepart of the evening, but was very violently affected by the crim- 

 son columns which formed about eleven o'clock. It is doubtful 

 whether I observed the greatest agitation of the needle at this time^ 

 for 1 did not commence my observations until the corona was almost 

 completely formed. This auroral arch was the only instance ob- 



