94 



ON THE PERIODICITY OF THE AURORA BOREALIS. 



Dec. 28. Kendal. Dalton. 

 " 30. Sagan. Preus. 



1791. 



Stockholm. Nicander. 



Salem. Holyoke. Lovering. 



Kendal. Dalton. 



Pyschminsk, Siberia. Hermann. 



Brussels. Mann. 



Sagan. Preus. Stockholm. Nicander. 



Sagan. Preus. Stockholm. Nicander. 



Sagan. Preus. 



Salem. Holyoke. Lovering. 



Pyschminsk, Siberia. Hermann. 



Pyschminsk, Siberia. Hermann. 



Mannheim. Hemmer. 



Mannheim. Hemmer. 



Sagan. Preus. 



Sagan. Preus. 



Eatisbon. Heinrich. 



Sagan. Preus. 



Kendal. Dalton. 



Sagan. Preus. 



Sagan. Preus. 



Kendal. Dalton. 



Stockholm. Nicander. Kendal. Dalton. 



Kendal. Dalton. 



Mannheim. Hemmer. 



Salem. Holyoke. Lovering. 



Salem. Holyoke. Lovering. 



Kendal. Dalton. 



Kendal. Dalton. 



Stockholm. Nicander. 



Salem. Holyoke. Lovering. 



Stockholm. Nicander. 



Kendal. Dalton. 



Stockholm. Nicander. Uhleaborg. Julin. 1 



Salem. Holyoke. Lovering. 



Mannheim. Hemmer. 



Sagan. Preus. 



Kendal. Dalton. 



Kendal. Dalton. 



Kendal. Dalton. 



Padua. Toaldo and Chiminello. 



Kendal. Dalton. 



Kendal. Dalton. 



Brussels. Mann. 



Mannheim. Hemmer. Brussels. Mann. 



1 Svenska Vetensk. Acad. XIV. 76. Voigt's Mag. fur. Phys. 

 XI. 3. p. 109. 



Kendal. Dalton. 



Sagan. Preus. 



Brussels. Mann. 



Mannheim. Hemmer. 



Brussels. Mann. 



Salem. Holyoke. Lovering. 



New Haven. Stiles. Loomis. 



Salem. Holyoke. Lovering. 



Salem. Holyoke. Lovering. 



Salem. Holyoke. Lovering. 



Stockholm. Nicander. 



Mannheim. Hemmer. 



Mannheim. Hemmer. 



Stockholm. Nicander. Kendal. Dalton. 



Kendal. Dalton. 



Stockholm. Nicander. Kendal. Dalton. 



Kendal. Dalton. 



Mannheim. Hemmer. 



Pyschminsk, Siberia. Hermann. 



Stockholm. Nicander. 



Stockholm. Nicander. 



Stockholm. Nicander. 



Kendal. Dalton. 



Stockholm. Nicander. 



Brussels. Mann. Kendal. Dalton. 



Stockholm. Nicander. 



Stockholm. Nicander. 



Munich. Imhof. 



Sagan. Preus. 



Kendal. Dalton. 



Kendal. Dalton. 



Kendal. Dalton. 



Brussels. Mann. 



Brussels. Mann. Kendal. Dalton. 



Sagan. Preus. Kendal. Dalton. 



Prague. Strnad. 



Stockholm. Nicander. Kendal. Dalton. 



Kendal. Dalton. 



Kendal. Dalton. 



Kendal. Dalton. 



Kendal. Dalton. 



Mannheim. Hemmer. 



Kendal. Dalton. 



Kendal. Dalton. 



Sagan. Preus. 



Kendal. Dalton. 



Brussels. Mann. Kendal. Dalton. 



Sagan. Preus. Stockholm. Nicander. 



Montreal. 1 



i Mem. Amer. Acad. II. 114. 



