ON THE PERIODICITY OF THE AURORA BOREALIS. 



31 



April 18. Celsius, Frobes, and Mairan. 



May 13. Bologna. Zanotti. Mairan. 



Aug. 1. Celsius, Frobes, and Mairan. 



" 6. Celsius, Frobes, and Mairan. 



" 22. Upsal. Burman. Celsius, Frobes, and Mairan. 



" 24. Celsius, Frobes, and Mairan. 



" 31. Celsius, Frobes, and Mairan. 



Sept. 3. Cola (Russia). Croyere. 1 



" 7. Celsius, Frobes, and Mairan. 



" 14. Celsius, Frobes, and Mairan. 



" 15. Cola. Croyere. 



" 18. Cola. Croyere. St. Petersburg. Kraft. 



" 18. The Delisles, Celsius, Frobes, and Mairan. 



" 22. St. Petersburg. Kraft. The Delisles. 



" 22. Frobes and Mairan. 



" 23. Celsius, Frobes, and Mairan. 



" 29. Cola. Croyere. 



" 30. Celsius, Frobes, and Mairan. 



Oct. 2. Celsius, Frobes, and Mairan. 



" 4. Cola. Croyere. 



" 5. Celsius, Frobes, and Mairan. 



" 6. Celsius, Frobes, and Mairan. 



" 9. Cola. Croyere. 



" 13. Frobes and Mairan. 



" 14. St. Petersburg. Kraft. The Delisles. 



" 14. Upsal. Burman. Celsius, Frobes, and Mairan. 



" 15. Cola. Croyere. *Sif. Petersburg. Kraft. 



" 15. The Delisles, Celsius, Frobes, and Mairan. 



" 17. Italy. Beccari. Frobes and Mairan. 



" 18. Italy. Beccari. Mairan. 



" 19. Berlin. Kirch. Cola. Croyere. 



" 19. Celsius, Frobes, Mairan, and Pilgram. 



" 20. Upsal. Burman. Celsius, Frobes, and Mairan. 



" 21. Celsius, Frobes, Mairan, and Pilgram. 



" 21. Upsal. Burman. 



," 27. Cola. Croyere. 



" 29. Cola. Croyere. 



Nov. 1. Cola. Croyere. 



" 3. Cola. Croyere. Celsius and Mairan. 



" 4. Frobes and Mairan. 



" 6. Frobes and Mairan. 



" 7. . Cola. Croyere. 



" 13. Cola. Croyere. 



" 16. Cola. Croyere. 



" 19. Cola. Croyere. 



" 20. Upsal. Burman. Celsius, Frobes, and Mairan. 



" 22. Cola. Croyere. 



" 23. Celsius and Mairan. 



1 Delisle, Mem. pour servir a l'Histoire de 1'Astronomie. 



Dec. 



Nov. 24. 

 " 25. 

 " 25. 

 " 27. 

 " 29. 

 2. 

 6. 

 6. 

 9. 

 11. 

 11. 

 15. 

 16. 

 17. 

 19. 

 20. 

 23. 

 26. 

 31. 



Jan. 



Feb. 



Mar. 



1. 



3. 

 12. 

 20. 

 29. 

 30. 



7. 



8. 



9. 

 10. 

 11. 

 11. 

 12. 

 12. 

 13. 

 13. 

 13. 

 13. 

 14. 

 26. 

 29. 



2. 



2. 



3. 



4. 



Celsius and Mairan. 



Between Cola and Kilduin. Croyere. 



Celsius and Mairan. 



Between Cola and Kilduin. Croyere. 



Behceen Cola and Kilduin. Croyere. 



Kilduin. Croyere. 



Kilduin. Croyere. 



Celsius, Frobes, and Mairan. 



Kilduin. Croyere. 



Between Kilduin and Cola. Croyere. 



Celsius, Frobes, and Mairan. 



Between Kilduin and Cola. Croyere. 



Celsius, Frobes, and Mairan. 



Sweden. Celsius. Frobes and Mairan. 



Siceden. Celsius. Frobes and Mairan. 



Si!. Petersburg. Kraft. The Delisles, Mairan. 



Cola. Croyere. 



Cola. Croyere. 



Cola. Croyere. 



1728. 



Sweden. Celsius, Frobes, and Mairan. 



Italy. Beccari. Mairan. 



Salem. Felt. 1 



Frobes and Mairan. 



St. Petersburg. Kraft. The Delisles, Mairan. 



Sweden. Celsius. Mairan. 



Utrecht. Musschenbroek. 2 Mairan, Pilgram. 



Sweden. Celsius. Frobes and Mairan. 



Siceden. Celsius. Frobes, Mairan, PiWam. 



Sioeden. Celsius. Frobes and Mairan. 



Utrecht. Musschenbroek. 



Sweden. Celsius. Frobes, Mairan, Pilgram. 



St. Petersburg. Kraft. The Delisles. 



Sweden. Celsius. Frobes and Mairan. 



Utrecht. Musschenbroek. 



St. Petersburg. Kraft. The Delisles. 



Berlin. Kirch. Pilgram. 



Sweden. Celsius. Frobes and Mairan. 



Sweden. Celsius. Frobes and Mairan. 



Celsius, Frobes, and Mairan. 



Celsius, Frobes, and Mairan. 



St. Petersburg. Kraft. The Delisles. 



Mairan and Pilgram. 



Si!. Petersburg. Kraft. The Delisles, Mairan. 

 St. Petersburg. Kraft. The Delisles, Mairan. 

 St. Petersburg. Kraft. The Delisles, Mairan. 



i Hist, of Salem, II. 

 2 Tab. Met., 1 728. 



