ON THE PERIODICITY OF THE AURORA BOREALIS. 



35 



Apr. 9. St. Petersburg. Kraft. The Delisles. Mairan. 



Plymouth. Huxham. Berlin. Kirch. 



Paris. Mairan. Frobes, Pilgram, and Short. 



Frobes and Mairan. 



St. Petersburg. Kraft. The Delisles. Mairan. 



Abo. Sporing. Celsius and Frobes. 



St. Petersburg. Kraft. The Delisles. Mairan. 



Italy. Beccari. Paris. Mairan. Pilgram. 



St. Petersburg. Kraft. The Delisles. Mairan. 



Frobes and Mairan. 



St. Petersburg. Kraft. The Delisles. Mairan. 



Abo. Sporing. Celsius, Frobes, and Mairan. 



Celsius, Frobes, and Mairan. 



Sweden. Celsius. Frobes and Mairan. 



Berlin. Kirch. Mairan. 



St. Petersburg. Kraft. The Delisles. 



Paris. Mairan. Frobes and Pilgram. 



Bologna. Zanotti and Beccari. 



Wittemberg. Weidler. Frobes and Mairan. 



Frobes and Mairan. 



Frobes and Mairan. 



Frobes and Mairan. 



Sweden. Celsius. Frobes and Mairan. 



Abo. Sporing. Celsius, Frobes, and Mairan. 



St. Petersburg. Kraft. The Delisles. Mairan. 



St. Petersburg. Kraft. The Delisles. 



Sweden. Celsius. Frobes and Mairan. 



St. Petersburg. Kraft. The Delisles. Mairan. 



Abo. Sporing. Celsius and Frobes. 



Sweden. Celsius. Frobes and Mairan. 



Abo. Sporing. 



Sweden. Celsius. Frobes and Mairan. 



Abo. Sporing. Celsius, Frobes, and Mairan. 



Sweden. Celsius. Frobes and Mairan. 



Sweden. Celsius. Frobes and Mairan. 



Abo. Sporing. 



Sweden. Celsius. Frobes and Mairan. 



St. Petersburg, Kraft. The Delisles. Mairan. 



Sweden. Celsius. Frobes and Thompson. 



Sweden. Celsius. Frobes and Mairan. 

 8. St. Petersburg. Kraft. The Delisles. 

 8. Plymouth. Huxham. Short. 



8. Sweden. Celsius. Frobes and Mairan. 



9. Sweden. Celsius. Frobes and Mairan. 

 10. Sweden. Celsius. Frobes. 



10. Mairan and Phil. Trans. 



11. Italy. Beccari. Mairan. 

 11. Sweden. Celsius. Frobes. 

 13. St. Petersburg. Kraft. The Delisles. Mairan. 

 17. St. Petersburg. Kraft. The Delisles. 



Sweden. 

 Berlin. 

 Sweden. 

 Sweden. 



Sept.17. 



" 20. 



" 21. 



" 27. 



" 27. 



" 28. 



" 30. 



" 30. 

 Oct. 3. 



" 4. 



" 4. 



" 5. 



" 5. 

 G. 

 6. 



" 7. 



" 7. 



" 7. 



" 8. 



" 8. 



" 9. 



" 9. 



" 9. 



" 9. 



" 10. 



" 11. 



" 11. 



" 12. 



" 12. 



" 14. 



" 16. 



" 17. 



" 17. 



" 20. 



" 23. 



" 20. 



" 21. 



" 22. 



" 23. 



" 23. 



" 26. 



Nov. 2. 



2. 



" 2. 

 2. 



" 2. 



" 2. 



« 3. 

 i Phil. Trans., XXXVII., 55. 

 2 Svenska Vetcnsk. Acad. Handl. XIII. 145. 



Sweden. Celsius. Frobes and Mairan. 

 Sweden. Celsius. Frobes and Mairan. 

 Sweden. Celsius. Frobes and Mairan. 

 Paris. Mairan. Pilgram. 

 Sweden. Celsius. Frobes. 



Celsius. Frobes and Mairan. 

 Kirch. Mairan. 



Celsius. Frobes. 



Celsius. Frobes and Mairan. 

 St. Petersburg. Kraft. The Delisles. Pilgram. 

 Sweden. Celsius. Frobes and Mairan. 

 Huxham. Plymouth. Sioeden. Celsius. 

 F robes, Mairan, Short, and Pilgram. 

 Huxham. Plymouth. Short. 

 Sweden. Celsius. Frobes and Mairan. 

 Plymouth. Huxham. Wittemberg. "Weidler. 

 Paris. Mairan. Abo. Sporing. 

 Sweden. Celsius. Frobes and Pilgram. 

 Berlin. Kirch. Abo. Sporing. 

 Sweden. Celsius. Frobes and Mairan. 

 St. Petersburg. Kraft. The Delisles. Pilgram. 

 Wittemberg. Weidler. Paris. Mairan. 

 Abo. Sporing. Celsius and Frobes. 

 Berlin. Kirch. 



Paris. Mairan. Abo. Sporing. Frobes. 

 St. Petersburg. Kraft. The Delisles. 

 Sweden. Celsius. Frobes and Mairan. 

 Sweden. Celsius. Frobes and Mairan. 

 Abo. Sporing. Pilgram. 

 Boue. 



Sweden. Celsius. Frobes and Mairan. 

 St. Petersburg. Kraft. The Delisles. 

 Sweden. Celsius. Frobes and Mairan. 

 St. Petersburg. Kraft. The Delisles. Mairan. 

 Mairan and Pilgram. 

 Berlin. Kirch. Celsius and Frobes. 

 Frobes and Mairan. 



St. Petersburg. Kraft. Frobes and Mairan. 

 <Si. Petersburg. Kraft. The Delisles. Pilgram. 

 Mairan and Pilgram. 

 Frobes and Mairan. 

 Paris. Mairan. Berlin. Kirch. 

 St. Petersburg. Kraft. The Delisles. 

 Cambridge, Mass. Winthrop and Greenwood. 1 

 Salem. Felt. Philadelphia. Kahn. 2 

 Annapolis, Maryland. Lewis. 

 Sweden. Celsius. Frobes and Thompson. 

 Berlin. Kirch. Mairan. 



