[ ^90 1 



These effeds were diftindly feen by three different people, 

 and their point of union marked feparately by each of them. 



There is certainly no reafon for confining the effects of aurora 

 borealis to the night, although it then makes its moft magnificent 

 difplay, contrafted by the darknefs of the iky. 



The tumulous motion of the ftars at certain times in ferene 

 ikies has been Uken notice of by the Abbe De La Caille at the 

 Cape of Good Hope ; and M. De La Lande remarks that fome- 

 times, when a fouth weft wind prevails at Paris, the fame effedt 

 is produced. An aurora borealis in this country is generally fuc- 

 -ceeded by a fouth weft wind, and frequently the wind veers round 

 to that point during its appearance ; now if this phaenomenon, as 

 fu2;geited by an ingenious member of this Academy, fhauld be 

 inflammable air in a flate of inflammation, the water fo produced 

 by fuch inflammation might fatisfadorily account for this unilea- 

 dinefs of the rays, whether we fuppofe it either in the ad of 

 abforption, or in the ftate of veficular vapour defcending from 

 the upper regions of the atmofphere. 



That inflammable air, at leait fome fpecies of it, contains iron, 

 cannot well be difputed, as its efi'edt on an infufion or tindure of 

 galls fhews the prefence of iron. That there is fome connedion, 

 hitherto unexplored, between magnetifm and the aurora borealis 

 feems highly probable. The unfteadinefs of the magnetic needle 

 during the appearance of this phaenomenon is known to every 

 one, and indicates fuch connedion j the union of the radii of a 



itrong 



