[ -9' ] 



ftrong aurora borealis in the pole of the dipping needle ftrengthens 

 the fame conjedlure, wiiich is flil! furtiier confirmed by tlie fitu- 

 ation of the luminous northern arch, generally the firft fymptora 

 of a ftrong aurora, and from whence, in all probability, the name 

 was taken ; for the higheft point of this arch is always found in 

 the magnetic meridian. 



This phasnomenon is certainly more common now than it was 

 a century or even half a century ago ; this I find moft people, 

 even the moft illiterate, agreed in. Upon examining the accounts 

 of the authenticated appearances of the aurora borealis, fo care- 

 fully colleded by the celebrated De Mairan, I perceive a chafm in: 

 the lift of obfervations for about forty years in the laft century, in- 

 the middle of which chafm, nearly, is the year 1661, in which 

 year we are told the variation of the needle at Paris was o... 

 "We feem alfo to colled from the fame author's refearches that the 

 frequency of this appearance feems to have decreafed with the 

 diminution of the eaftern variation, and it now feems to encreafe 

 with the encreafing weftern variation. What real connedion 

 there may be between the variation of the needle and the aurora 

 borealis, or the caufe of it, I acknowledge myfelf entirely igno- 

 rant ; but perhaps this trifling hint may engage the attention of 

 others who have both coore leifure and abilities for fuch an inte- 

 refling difquifition. ' 



