256 



ON THE PERIODICITY OF THE AURORA BOREALIS. 



Dec. 



Sept. 5. 

 *Nov. 17. 



* " 18. 



* " 18. 

 " 24. 



8. 



8. 

 10. 

 13. 

 23. 



Feb. 20. 

 *March 17. 



" 23. 



♦.May 20. 



♦Sept. 13. 



" 14. 



* « 15. 



" 16. 



" 30. 



Wasa. Von 

 Helsingfors. 

 Helsingfors. 

 Wasa. Von 

 Helsingfors. 

 Helsingfors. 

 Wasa. Von 

 Helsingfors. 

 Helsingfors. 

 Helsingfors. 



Schoultz. 

 Argelander. 

 Argelander. 

 Schoultz. 

 Argelander. 

 Argelander. 

 Schoultz. 

 Argelander. 

 Argelander. 

 Argelander. 



1836. 

 Helsingfors. Argelander. 1 

 Helsingfors. Argelander. 2 

 Helsingfors. Argelander. 

 Paris. Bouvard. 8 

 Helsingfors. Argelander. 



Helsingfors. Argelander. 



Helsingfors. Argelander. 

 Hels in gfors. Argel ander. 

 Helsingfors. Argelander. 



Oct. 8. Helsingfors. Argelander. 



* " 11. Helsingfors. Argelander. 



* " 11. Braunsberg. Fcldt. Wolf. 4 

 " 12. Helsingfors. Argelander. 

 " 12. Braunsberg. Feldt "Wolf. 



* " 15. Helsingfors. Argelander. 



* " 18. Helsingfors. Argelan 



* " 18. Wasa. Von Schoultz. Braunsberg. 

 " 19. Switzerland? Vogel. Wolf. 



Nov. 27. Augsburg? Stark. Wolf. 



1837. 

 *Jan. 25. Philadelphia. Peirce. 6 



* " 25. Helsingfors. Argelander. 

 Feb. 13. Augsburg? Stark. Wolf. 



" 14. Zurich? Wolf. 6 



* " 18. Paris. Bouvard. 7 



* " 18. Helsingfors. Argelander. 



*March 29. Zurich ? Wolf. " 



• 



1 Wolf assigns this aurora to Feb. 22. 



2 According to the Vermont Chronicle only one aurora was 

 seen in the winter of 1835-6, though twelve appeared in the 

 preceding winter. — American Almanac, 1838, p. 179. 



» Connaiss. de Terns., 1840, p. 397. 



* Pogg. Annalen der Physii, 2X1., 54-3. 



5 Meteor. Account of the Weather, pp. 29 and 228. 



6 Meteor. Beobacht. der Naturforsch. Gesellsch. in Zurich. 



7 Connaiss. de Terns., 1841, p. 417. 



May 2. Augsburg? Stark. Wolf. 



July 28. Augsburg? Stark. Wolf. 



*Oct. 6. Paris. Bouvard. 



18. Pekin. Kupffer. 



5. Paris. Bouvard. 



6. Augsburg. Stark. Wolf. 

 12. Paris. Bouvard. 



14. Philadelphia. Peirce. Pari.-;. Bouvard. 



15. Paris. Bouvard. 

 15. Cat/. rg. Kupffer. 



1838. 



Oct. 21. Bravais. Wolf. 1 



1 BuUetin de l'Acad. Roy. Brux. VIII., 45. 

 - Med. and Surer. Jonrn., XX. 35, 163, 291. 

 3 Annal. de l'Observ. Physique Centrale de Russii 

 Suppl. pp. 15 et 119. 

 4 Meteorolog. Beobacht. Zurich. 

 ' Med. and Surg. Jonrn., XXL. 151, 231, and 295. 



