ON THE PERIODICITY OF THE AURORA BOREALIS. 



65 



Oct. 20. St. Petersburg. Euler. 1 



" 28. St. Petersburg. Euler. 



Nov. 3. Cambridge. Winthrop. Lovering. 



" 3. Franeker. Cotte. St. Petersburg. Euler. 



" 5. Cambridge. Winthrop. Lovering. 



" 5. Franeker. Cotte. St. Petersburg. Euler. 



" 7. St. Petersburg. Euler. 



" 11. Franeker. Cotte. 



" 24. St. Petersburg. Euler. 



■ 26. St. Petersburg. Euler. 



Dee. 1. Franeker. Cotte. St. Petersburg. Euler. 



" 1. Newport, R. I. Stiles. Loomis. 



" 4. Marseilles. Cotte. 



" 26. St. Petersburg. Euler. 



" 28. St. Petersburg. Euler. 



1775. 



Jan. 1. St. Petersburg. Euler. 2 



6. Franeker. Cotte. 



20. Montmorenci and Franeker. Cotte. 



21. Montmorenci and Franeker. Cotte. 



21. St. Petersburg. Euler. 



22. St. Petersburg. Euler. 



23. Franeker. Cotte. St. Petersburg. Euler. 



24. Franeker. Cotte. 



25. Franeker. Cotte. St. Petersburg. Euler. 



26. St. Petersburg. Euler. 



27. St. Petersburg. Euler. 



28. Montmorenci and Franeker. Cotte. 



29. Cambridge. Winthrop. Lovering. 

 29. Newport, R. I. Stiles. Loomis. 



29. St. Petersburg. Euler. 



30. Franeker. Cotte. 

 Feb. 1. Brussels. Cotte. 



2. Cambridge. Winthrop. Lovering. 

 4. Brussels. Cotte. 



19. Franeker. Cotte. St. Petersburg. Euler. 



20. Bordeaux. Cotte. St. Petersburg. Euler. 



21. Cambridge. Winthrop. Lovering. 

 21. Franeker. Cotte. St. Petersburg. Euler. 

 23. St. Petersburg. Euler. 

 28. Franeker. Cotte. 



Mar. 19.* Franeker. Cotte. 

 « 20. Franeker. Cotte. 



1 All the St. Petersburg observations from Jan. 17, 1772 to 

 the bottom of page 64 should be corrected by subtracting 1 1 

 days from their respective dates : the error having originated in 

 reducing to new style dates already corrected. 



2 N. Comm. Petrop. XX. 643. 



VOL. X. 9 



Mar. 21. 



" 22. 



" 24. 



" 25. 



" 26. 



" 27. 



" 28. 



" 29. 



" 30. 

 Apr. 1. 



" 2. 

 4. 



" 13. 



" 15. 



" 17. 



" 18. 



" 19. 



" 20. 



" 23. 

 May 2. 



" 15. 



" 20. 

 July 18. 



" 20. 



" 21. 

 Aug.24. 



" 27. 

 Sept.15. 



" 16. 



" 17. 



" 19. 



" 22. 



" 23. 



" 24. 



" 27. 

 Oct. 13. 



" 18. 



" 21. 

 Nov. 23. 

 Dec. 15. 



Jan. 18. 



" 18. 



« 20. 



" 21. 

 Feb. 11. 



Franeker. Cotte. 

 St. Petersburg. Euler. 

 St. Petersburg. Euler. 

 Cambridge. Winthrop. 



Lovering- 



Franeker. 



Franeker. 



Franeker. 



Franeker. 



Franeker. 



St. Petersburg. 



St. Petersburg. 



Cotte. 

 Cotte. 

 Cotte. 

 Cotte. 

 Cotte. St. Petersburg. 



Euler. 



Euler. 



Euler. 



Franeker. 

 Franeker. 

 Franeker. 

 Franeker. 

 Franeker. 

 Franeker. 

 Franeker. 



Cotte. 

 Cotte. 

 Cotte. 

 Cotte. 

 Cotte. 

 Cotte. 

 Cotte. 



St. Petersburg. Euler. 

 Franeker. Cotte. 



Franeker. 



Franeker. 



Cambridge 



Franeker. 



Franeker. 



St. Petersburg. 



St. Petersburg. 



Cotte. 

 Cotte. 



Winthrop. 

 Cotte. 

 Cotte. 



Euler. 



Euler. 



Lovering. 



Franeker. Cotte. 



Franeker. Cotte. 



Montmorenci and Franeker. Cotte. 



Vire. Normandy. Cotte. 



Franeker. Cotte. 



Franeker. Cotte. 



St. Petersburg. Euler. 



Franeker. Cotte. St. Petersburg. Euler 



St. Petersburg. Euler. 



Brussels. Cotte. 



Vienna. Pilgrarn. 



Franeker. Cotte. 



Franeker. Cotte. Berlin. Beguelin. 



1776. 



Berlin. Beguelin. 

 St. Petersburg. Euler. 1 

 Franeker. Cotte. 

 Franeker. Cotte. Berlin. 

 Franeker. Cotte. 



Beguelin. 



1 Acta Sci. Acad. Petrop. 1777, Pt. 1, p. 384. 



