ON THE PERIODICITY OF THE AURORA BOREALIS. 



55 



1 An aurora was seen at Constantinople in 1754. Phil. Trans. 

 XLIX. 119. 



2 Svenska Vetensk. Acad. XVI. 290. 



8 Mem. de l'Acad. Sav. Etrang. III. 581. 



* Svenska Vetensk. Acad. XVIII. 61. 



* Svenska Vetensk. Acad. XVIII. 208. 



6 N. Comm. Petrop. VII. 405. 



7 Aurora Australis. 



8 Once in Upsal in January. 



9 Svenska Vetensk. Acad. XIX. 231. 



" 4. Hernosand. Gisler. Boue. 

 " 15. Upsal. Bergman. Thompson. 

 " 15. Hernosand. Gisler. Bou& 



1 Mem. de l'Acad. Sav. Etrang. IV. 242. 



2 Mem. de l'Acad. Sav. Etrang. IV. 597. 



3 Phil. Trans. LII. 474. 



♦ N. Comm. Petrop. IX. 418. 



6 Svenska Vetensk. Acad. XIX. 315. 



6 Nova Acta Sci. UpsaL I. 418 and Phil. Trans. LII. 479. 



