ON THE PERIODICITY OF THE AURORA BOREALIS. 



29 



Jan. 30. 

 Feb. 4. 



" 11. 

 Mar. 24. 



" 25. 



" x. 

 April 14. 

 May 4. 



" 22. 

 Aug. 4. 



" 12. 



" 17. 



" 24. 



" 31. 

 Sept. 9. 



" 22. 



" 23. 

 Oct. 16. 



" x. 

 Nov. 8. 



" 9. 



" 16. 

 Dec. 6. 



" 7. 



" 8. 



" 25. 



Jan. 7. 



" 8. 

 9. 



" 12. 



" 13. 

 Feb. 6. 



" 9. 



" 11. 



" 12. 



" 15. 

 Mar. 16. 

 April 2. 



" 17. 



" 24. 



May 2. 



Sept. 6. 



" 9. 



" 11. 



" 16. 



" 19. 



Frobes and Mairan. 



Frobes and Mairan. 



Siveden. Celsius. Frobes and Mairan. 



Celsius, Frobes, and Mairan, 



Upsal. Burman. Frobes and Mairan. 



Mairan and Pilgram. 



Upsal. Burman. Celsius, Frobes, and Mairan 



Celsius, Frobes, and Mairan. 



Celsius, Frobes, and Mairan. 



Frobes and Mairan. 



Frobes and Mairan. 



Celsius, Frobes, and Mairan. 



Frobes and Mairan. 



Frobes and Mairan. 



Frobes and Mairan. 



Frobes and Mairan. 



Frobes and Mairan. 



Upsal. Burman. Frobes and Mairan. 



Mairan and Pilgram. 



Upsal. Burman. Celsius, Frobes, and Mairan. 



Sweden. Celsius. Mairan. 



Upsal. Burman. Frobes and Mairan. 



Upsal. Burman. Frobes and Mairan. 



Upsal.^ Burman. Frobes and Mairan. 



Upsal. Burman. Frobes and Mairan. 



Frobes and Mairan. 



1725. 

 Sweden. Celsius, Frobes, and Mairan. 

 Celsius, Frobes, and Mairan. 

 Celsius, Frobes, Mairan, and Pilgram. 

 Celsius, Frobes, and Mairan. 

 Celsius, Frobes, and Mairan. 

 Frobes and Mairan. 



Sweden. Celsius. Frobes and Mairan. 

 Frobes and Mairan. 

 Berlin. Kirch. Mairan. 



Burman. 1 Frobes and Mairan. 



Kirch. Mairan. 



Burman. Frobes and Mairan. 



Burman. Frobes and Mairan. 



Kirch. Mairan. 

 Celsius and Mairan. 

 Upsal. Burman. 2 

 Upsal. Burman. 

 Upsal. Burman. 

 Mairan and Short. 

 Upsal. Burman. 



Upsal. 

 Berlin. 

 Upsal. 

 Upsal. 

 Berlin. 



1 Acta Lit. Suecirc, II. 141. 



Frobes and Mairan. 

 2 Ibid., III. 



Jan. 

 u 



Feb. 

 Mar. 



21. 



3. 

 19. 



7. 

 2. 

 6. 

 " 10. 

 " 10. 

 " 14. 

 " 24. 

 " 25. 

 " 26. 

 " 26. 

 " 27. 

 " 27. 

 " 27. 

 " 28. 

 April 2. 

 " 23. 

 5. 

 26. 

 28. 

 10. 

 14. 

 14. 

 15. 

 17. 



Sept. 



Oct. 



Berlin. Kirch. Ireland. Dobbs. 1 



Sweden. Celsius. Frobes. 



Upsal. Burman. Mairan and Pilgram. 



Ireland. Dobbs. 



Celsius, Mairan, and Pilgram. 



Ireland. Dobbs. Berlin. Kirch. 



Lynn. Rastrick. Upsal. Burman. Celsius. 



Frobes, Mairan, and Pilgram. 



Celsius, Frobes, and Mairan. 



Celsius, Frobes, and Mairan. 



Mairan and Short. 



Mairan and Short 



Upsal. Burman. Celsius, Frobes, and Mairan. 



Celsius, Frobes, and Mairan. 



Celsius, Frobes, and Mairan. 



Celsius, Frobes, and Mairan. 



Celsius, Frobes, and Mairan. 



Sweden. Celsius. Frobes and Mairan. 



1726. 

 Mairan and Short. 



Sweden. Celsius. Frobes and Mairan. 

 Celsius, Frobes, and Mairan. 

 Upsal. Burman. 2 Frobes and Mairan. 

 Mairan and Phil. Trans. 

 Frobes, Mairan, and Phil. Trans. 

 Upsal. Burman. 



Upsal. Burman. Frobes, Mairan, Phil. Trans. 

 Celsius, Frobes, and Mairan. 

 Mairan and Phil. Trans. 

 Frobes, Mairan, and Phil. Trans. 

 Upsal. Burman. 



St. Petersburg. Kraft. 3 The Delisles. 

 Upsal. Burman. Celsius and Frobes. 

 Mairan and Phil. Trans. 

 Mairan and Phil. Trans. 

 Phil. Trans, and Mairan. 

 Phil. Trans, and Mairan. 

 Celsius, Frobes, and Mairan. 

 Near Paris. Mairan. Pilgram. 

 Celsius, Frobes, and Mairan. 



Short. 



Lynn. Rastrick. 4 



Upsal. Burman. Frobes, Mairan, and Short. 



Lynn. Rastrick. Short. 



Frobes, Mairan, and Phil. Trans. 



i Phil. Trans., XXXIV. 128. 



2 Acta Lit. Sueciae, II. 257. 



3 Coram. Petrop., IX. 



4 Phil. Trans., XXXIV. 255. 



