1852.] MAGNETOMETER AFFECTED. 179 



bitions of aurora occurred, and some slight deflections 

 of the magnetometer were apparent, but generally pre- 

 ceding or following. 



About three A.M. on the 12th, the aurora was reported 

 by the officer of the watch as very brilliant. But as I 

 was comfortably in bed, and it was beyond my exami- 

 nation and would vanish before I could possibly be in 

 a proper state to receive such a delicate visitor, I direct- 

 ed Messrs. May and Cheyne to pay every attention. It 

 was Mr. May's guard at the magnetometer, and Mr. 

 Cheyne was excused watch solely to attend to the elec- 

 trometers, etc. It was asserted that the electric fluid was 

 noticed on the wires fairly caught ; certes Mr. Cheyne 

 found no disturbance. I am not quite sure that he had 

 his instruments placed in connection with his wires, or 

 that he reached in time, possibly thinking as I did (?). 

 Mr. May repaired to the Observatory, and unfortunately 

 niy later orders were not then in force, or we should 

 have had a full history of this visitation. The magne- 

 tometer exhibited the most unmistakable signs of dis- 

 turbance, moving instantaneously from 114 to 128, and 

 up to 150, returning at four A.M. to 117'90. 



This, then, I consider as strong proof; and taking into 

 consideration other very decided deflections, when no 

 cause was apparent, I am induced to believe that the af- 

 fection precedes or follows what may be indistinct, or not 

 at all noticed by simple atmospheric observers, and no- 

 thing short of very close watching at the magnetometer 

 will indicate the truth. But it must be borne in mind 

 that this extra duty is a delicate service, and, to maintain 

 even moderate interest, I know full well that the greatest 



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