AURORA BOREALIS OF NOVEMBER 17, 1848. 



631 



Table II. Readings of the Horizontal Force Magnet in parts of the whole horizontal force, 

 about the time of the Aurora Borealis of November 17, 1848, as observed at the Royal Observatory 

 of Greenwich, the whole force being reckoned 10,000, and increasing numbers denoting an increase 

 of force. 



These observations were accompanied by the following remarks : 



" Between 7" . 23" and 7" . 40" small changes were constant. Between 8" . 14" and 8*' . 24", and 

 again between 8". 40" and S"". 45", the registering pencil of liglit went beyond the photographic 

 paper. The same thing happened at lO"". 2", and the light remaining oH' the paper, the reniuining 

 observations, commencing at 12''. 0", were made independently of the self-registering apparatus." 



4M 2 



