68 



ON THE PERIODICITY OF THE AURORA BOREALIS. 



Vienna. Pilgram. 



Franeker. Van Swinden. Holland. Cotte, 



Holland. Cotte. 



St. Petersburg. Euler. 



Cambridge. Winthrop. Lovering. 



Chinon. Cotte. 



Cambridge. Winthrop. Lovering. 



Portsmouth, N. H. Stiles. Loomis. 



Chinon. Cotte. St. Petersburg. Euler. 



St. Petersburg. Euler. 



Jena. Zeissing. Havre. Dicquemare. 1 



Montmorenci, fyc. Cotte. 



Vienna. Pilgram. Franeker. Van Swinden. 



St. Petersburg. Euler. 



Holland, fyc. Cotte. 



St. Malo. Cotte. 



Perpignan. Cotte. 



Gurzelen. Spriingli. Wolf. 



St. Petersburg. Euler. 



Cambridge. Winthrop. Lovering. 



Beziers. Bertholon. Havre. Diquemare. 2 



Franeker and Holland. Van Swinden. 



Montmorenci. Cotte. St. Petersburg. Euler. 



Montmorenci. Cotte. St. Petersburg. Euler. 



Holland. Cotte. 



Cambridge. Winthrop. Lovering. 



Berlin. Beguelin. 



Franeker. Van Swinden. 



Holland. Cotte. St. Petersburg. Euler. 



Cambridge. Winthrop. Lovering. 



Berlin. Beguelin. 



Franeker. Van Swinden. 



St. Petersburg. Euler. 



Montmorenci and Holland, fyc. Cotte. 



Franeker. Van Swinden. 



Holland. Cotte. 



Berlin. Beguelin. 8 



St. Petersburg. Euler. 



Copenhagen. Cotte. 



Jena. Zeissing. 



St. Petersburg. Euler. 



Berlin. Beguelin. 



Berlin. Beguelin. 



Cambridge. Winthrop. Lovering. 



1 Journ. de Phys. XI. 269. 



» Jonrn. de Phvs. XI. 420. 



» Dicquemare saw auroras at Havre on the last days of- 

 Mareh and on the first ten days of April, 1*78. Eneyc. Method I. 

 347. 



Apr. 21. 

 " 21. 

 " 23. 

 " 23. 

 « 25. 

 " 26. 

 " 26. 

 May 13. 

 " 14. 

 " 14. 

 June 10. 

 " 11. 



« 14. 



" 26. 



" 28. 



" 28. 



" 28. 



" 28. 



" 28. 

 July 3. 



" 7. 



" 15. 



" 31. 

 Aug. 12. 



" 22. 



" 28. 



" 28. 

 Sept. 1. 



" 3. 



Breda and Holland. Cotte. 



St. Petersburg. Euler. 



Cambridge. AVinthrop. Lovering. 



Provence. Cotte. St. Petersburg. 



Isle d' Oleron. Cotte. 



Cambridge. Winthrop. Lovering. 



Berlin. Beguelin. 



Cambridge. Winthrop. Lovering. 



Franeker. Van Swinden. 



Holland. Cotte. 



Franeker. Van Swinden. Cotte. 



Franeker. Van Swinden. Cotte. 



Cambridge. Winthrop. Lovering. 



Havre. Dicquemare. 



Cambridge. Winthrop. Lovering. 



Sinigaglia. De Toschi de Fagnaro. 1 



Franeker. Van Swinden. Reus-;. 



Montmorenci and Cadiz, S,c. Cotte. 



Spain. Rico. 



Perpignan. Cotte. 



Cambridge. Winthrop. Lovering. 



Franeker. Van Swinden. Cotte. 



Cambridge. Winthrop. Lovering. 



Franeker. Van Swinden. 



Franeker and Holland. Cotte. 



Breda. Cotte. Berlin. Beguelin. 



Euler. 



Euler. 



Euler. 



Euler. 



11. 

 12. 

 15. 

 15. 

 17. 

 17. 

 18. 

 18. 

 19. 

 20. 

 21. 

 21. 

 21. 

 22. 

 22. 

 22. 

 22. 

 22. 



St. Petersburg. 

 St. Petersburg. 

 St. Petersburg. 

 Spain. Rico. 

 St. Petersburg. 

 St. Petersburg. 

 Franeker. 

 Franeker. 



Euler. 



Euler. 

 Van Swinden. 

 Van Swinden. 



Montmorenci. Cotte. St. Petersburg. Euler. 

 Copenhagen and Holland. Cotte. 

 Berlin. Beguelin. 

 Viviers. Cotte. 

 Mur-de-Barez. Cotte. 

 Franeker. Van Swinden. 

 Montmorenci, Holland, fyc. Cotte. 

 Jena. Zeissing. St. Petersburg. Euler. 

 Cambridge. Winthrop. Lovering. 

 New Haven. Stiles. Loomis. 

 Moyitmorenci, Bordeaux, Sfc. Cotte. 

 Louvain. Chevalier. 2 St. Petersburg. Euler. 

 Jena. Zeissing. Bildersael. Pilgram. 



l Jonrn. de Phys. X. 232. Mem. del'Acad. Berlin, 1779. p. 14. 

 s Me'm. de 1'Acad. Brux. HI. p. xxvi. 



