ON THE PERIODICITY OF THE AURORA BOREALIS. 



91 



22. 



Paris. Cassini. 



New Haven. Stiles. Loorais. 



Kendal. Dalton. Paris. Cassini. 



Ratisbon. Heinrich. 



Salem. Holyoke. Lovering. 



New Haven. Stiles. Loomis. 



New Haven. Stiles. Loomis. 



Ratisbon. Heinrich. 



Salem. Holyoke. Lovering. 



New Haven. Stiles. Loomis. 



Salem. Holyoke. Lovering. 



Ratisbon. Heinrich. 



Salem. Holyoke. Lovering. 



Salem. Holyoke. Lovering. 



Salem. Holyoke. Lovering. 



Brussels. Mann. . 



Neiv Haven. Stiles. Loomis. 



Salem. Holyoke. Lovering. 



New Haven. Stiles. Loomis. 



Brussels. Mann. 



New Haven. Stiles. Loomis. 



Brussels. Mann. 



Bncssels. Mann. 



Salem. Holyoke. Lovering. 



Brussels. Mann. 



Brussels. Mann. 



Paris. Cassini. 



Cambridge. Wigglesworth. Lovering. 



Salem. Holyoke. Lovering. 



Neiv Haven. Stiles. Loomis. 



Cambridge. Wigglesworth. Lovering. 



Salem. Holyoke. Lovering. 



New Haven. Stiles. Loomis. Laon. Cotte. 



Salem. Holyoke. Lovering. 



Brussels. Mann. 



Keswick. Dalton. 



Stockholm. Nicander. 



Sagan. Preus. Kendal. Dalton. 



Paris. Cassini. Kendal. Dalton. 



Kendal. Dalton. 



Kendal. Dalton. Stockholm. Nicander. 



Cambridge. Wigglesworth. Lovering. 



Salem. Holyoke. Lovering. 



Kendal. Dalton. 



Kendal. Dalton. St. Petersburg. Euler. 



Peissenberg. Schwaiger. Sagan. Preus. 



Berne. Studer. 



Kendal. Dalton. 



Stockholm. Nicander. St. Petersburg. Euler. 



Stockholm. Nicander. 



Aug. 24. 



" 24. 



" 24. 



" 24. 



" 25. 



" 25. 



" 25. 



" 26. 



" 28. 



" 29. 

 Sept. 9. 



" 10. 



" 12. 



" 13. 



" 14. 



" 15. 



" 16. 



" 17. 



" 20. 



" 20. 



" 21. 



" 21. 



" 22. 



" 23. 



" 24. 



" 25. 



" 26. 



« 26. 



" 26. 



" 26. 



« 26. 



" 27. 2 



" x. 

 Oct. II. 3 



" 12. 



" 13. 



" 16. 



« 18. 



" 19. 



" 19. 



" 19. 



« 19. 



" 19. 



" 20. 



« 20. 



" 20. 



Cambridge. Wigglesworth. Lovering. 



Salem. Holyoke. Lovering. 



Stockholm. Nicander. Paris. Cassini. 



St. Petersburg. Euler. 



Sagan ? Preus. Ratisbon. Heinrich. 



Stockholm. Nicander. 



Paris. Cassini. Kendal. Dalton. 



Stockholm. Nicander. 



Stockholm. Nicander. 



Stockholm. Nicander. 



Salem. Holyoke. Lovering. 



Stockholm. Nicander. 



Stockholm. Nicander. 



Stockholm. Nicander. 



Stockholm. Nicander. Kendal. Dalton. 



Kendal. Dalton. 



St. Petersburg. Euler. 



Brussels. Mann. 



Stockholm. Nicander. 



Kendal. Dalton. Sagan. Preus. 



Salem. Holyoke. 

 Brussels. Mann. 

 Salem. Holyoke. 

 Kendal. Dalton. 

 Sagan. Preus. 

 Sutz. Spriingli. 

 Kendal. Dalton. 



Lovering. 



Lovering. 



Berne. Studer. 

 Falaise. Hervieu. 1 

 Rochelle. Seignette. Laon. Cotte. 

 Mannheim. Hemmer. 

 Peissenberg. Schwaiger. Berne. Studer. 

 Brussels. Mann. Paris. Cassini. 

 Stockholm. Nicander. Sagan ? Preus. 

 Falaise. Hervieu. Boue\ 

 St. Petersburg. Euler. 

 Stockholm. Nicander. 

 Stockholm. Nicander. 

 Salem. Holyoke. Lovering. 

 Kendal. Dalton. *S!f. Petersburg. Euler. 

 Cambridge. Wigglesworth. Loverin". 

 Salem. Holyoke. Lovering. 

 New Haven. Stiles. Loomis. 

 Kendal. Dalton. St. Petersburg. Euler. 

 Marseilles. St. Jacques. Moscow. Stritter. 

 Kendal. Dalton. St. Petersburg. Euler. 

 Jena. Zeissing. Moscoio. Stritter. 

 Brussels. Mann. Paris. Cassini. 



1 Encyc. Method. I. 368. 



2 Joura. de Phys. XXXVI. 440. 



3 An aurora was seen in Spain on one day of this month. 



