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PROFESSOR CHALLIS'S OBSERVATIONS OF THE 



The following are the Tables of Magnetic Observations referred to in the foregoing com- 

 munication. 



Table I. The Westerly Declinations of the Declination Magnet about the time of the Aurora 

 Borealis of November 17, 1848, as observed at the Royal Observatory of Greenwich. 



To these observations the following remarks were attached : 



" The magnet began to be disturbed at o" . 50™." 



" Rapid changes occurred from 6'' to S""." 



" It is not known to what extent the Magnet moved between g** . 25" and 9*" . 44" on one side, 

 and between lo"". 10" and lO*" . 40" on the other. The motion at these times was smooth and 

 certainly without any checked motion whatever." 



