ON THE PERIODICITY OF THE AURORA BOREALIS. 



33 



Oct. 17. Celsius and Mairan. 



" 18. Cola. Croyere. Mairan and Phil. Trans. 



" 19. Cola. Croyere. Mairan and Phil. Trans. 



" 24. Redbridge. Derham. 1 Mairan. 



" 24. Siceden. Celsius. Frobes and Pilgram. 



" 25. St. Petersburg. Kraft. The Delisles. 



" 25. Plymouth. Huxham. Short. 



" 25. Mairan. Pilgram. 



" 26. Plymouth. Huxham. 



" 26. Cola. Croyere. Phil. Trans, and Mairan. 



" 27. St. Petersburg. Kraft. The Delisles. Mairan. 



" 29. Utrecht. Musschenbroek. 



" 29. Cola. Croyere. Mairan. 



" 29. Pilgram and Phil. Trans. 



" 30. St. Petersburg. Kraft. The Delisles. 



" 30. Italy. Beccari. 



" 30. Utrecht. Musschenbroek. 



" 30. Mairan, Pilgram, and Phil. Trans. 



" 31. Cola. Croyere. 



Nov. 2. St. Petersburg. Kraft. The Delisles. 



" 2. Plymouth. Huxham. Utrecht. Musschenbroek. 



" 2. Celsius, Frobes, and Mairan. 



" 2. Pilgram and Phil. Trans. 



" 3. Mairan and Phil. Trans. 



" 4. Mairan. Pilgram. 



" 5. Upsal. Burman. Celsius. 



" 5. Frobes and Mairan. 



" 7. St. Petersburg. Kraft. The Delisles. Mairan. 



" 8. Celsius, Frobes, and Mairan. 



" 12. Berlin. Kirch. Mairan. 



" 13. Berlin. Kirch. Mairan. 



" 15. Cola. Croyere. 



" 16. Cola. Croyere. 



" 22. Cola. Croyere. 



" 22. Sweden. Celsius. 



" 23. Utrecht. Musschenbroek. 



" 23. Sweden. Celsius. 2 Frobes. 



" 23. Pilgram and Phil. Trans. 



" 27. Cola. Croyere. 



" 29. Cola. Croyere. 



Dec. 2. Italy. Beccari. Mairan. 



" 3. St. Petersburg. Kraft. The Delisles. 



" 3. Plymouth. Huxham. Mairan and Short. 



" 4. Frobes and Mairan. 



" 7. Cola. Croyere. 



« 10. Cola. Croyere. 



1 Phil. Trans., XXXVI. 137. 



2 Boue quotes Celsius for October 1 1 and 24 ; but Mairan 

 does not mention these days. 



VOL. X. 5 



Frobes and Mairan. 



Mairan. 



Dec. 14. 



« 15. 

 " 27. 

 " 31. 



Jan. 14. 



" 15. 



" 17. 



" 17. 



" 17. 



" 18. 



" 19. 



« 20. 



" 24. 



" 25. 



" 28. 

 Feb. 2. 



" 3. 



" 3. 



" 7. 



" 11. 



" 16. 



" 17. 



" 23. 



" 25. 



" 27. 



" 28. 

 Mar. 2. 



" 15. 



" 16. 



" 25. 



" 27. 



" 28. 



" 30. 

 Apr. 6. 



" 19. 



" 22. 



" 24. 



" 27. 



" 28. 



" 30. 



May 1. 



2. 



" 2. 



" 17. 



" 22. 



" 26. 



" 27. 



" 29. 



Frobes and Mairan. 



Cola. Croyere. 



Cola. Croyere. 



Sweden. Celsius. Frobes and Mairan. 



1729. 



Sweden. Celsius. Frobes and Mairan. 



Cola. Croyere. 



Plymouth. Huxham. Short. 



Celsius, Frobes, and Mairan. 



Pilgram and Phil. Trans. 



Celsius and Mairan. 



Between Cola and Kilduin. Croyere. 



Frobes and Mairan. 



Frobes and Mairan. 



Plymouth. Huxham. 



Kilduin. Croyere. 



Sweden. Celsius. Frobes and Mairan. 



Kilduin. Croyere. 



Sweden. Celsius. Frobes and Mairan. 



Between Kilduin and Cola. Croyere. 



Celsius and Mairan. 



Celsius, Frobes, and Mairan. 



Cola. Croyere. Frobes and Mairan. 



Cola. Croyere. 



Sweden. Celsius. Frobes and Mairan. 



Sweden. Celsius. Frobes and Mairan. 



Sweden. Celsius. Frobes and Mairan. 



Celsius, Frobes, and Mairan. 



Sweden. Celsius. Frobes and Mairan. 



Sweden. Celsius. Frobes and Mairan. 



Sweden. Celsius. Frobes and Mairan. 



Celsius, Frobes, and Mairan. 



Sweden. Celsius. Frobes and Mairan. 



Sweden. Celsius. Frobes and Mairan. 



Sweden. Celsius. Frobes and Mairan. 



Frobes and Mairan. 



Plymouth. Huxham. Mairan and Short 



Sweden. Celsius. Frobes and Mairan. 



Sweden. Celsius. Frobes and Mairan. 



Sweden. Celsius. Frobes and Mairan. 



Frobes and Mairan. 



Celsius, Frobes, and Mairan. 



St. Petersburg. Kraft. The Delisles. Mairan. 



Plymouth. Huxliam. Sweden. Celsius. Frobes. 



Plymouth. Huxham. Mairan and Short. 



Celsius, Frobes, and Mairan. 



Celsius and Mairan. 



Celsius and Mairan. 



St. Petersburg. Kraft. Frobes. 



