ON THE PERIODICITY OF THE AURORA BOREALIS. 



77 



1 Aurora Australia. 



2 Phil. Trans. LXXX. 101. 



8 Acta Sci. Acad. Petrop. 1767. Pt. II. p. 303. 



4 Kot in the Berlin Memoirs, but in Ephem. Soc. Met. Palat. 



Berlin. Beguelin. 



Padua. Toaldo and Chiminello. 



Spydberg. Wilse. 



Spydberg. Wilse. 



Peissenberg. Schwaiger. 



Laon. Cotte. 1 



Erfurt. Planer. Jena. Zeissing. 



Laon. Cotte. 



Cambridge. Wigglesworth. Lovering. 



Rochelle. Seignette. 



Rochelle. Seignette. 



Ratisbon. Heinrich. 



St. Veran. Roberjot. 2 



St. Veran. Roberjot. 



Delphi? Van Swinden. 



Berlin. Beguelin. 



Mannheim. Hemmer. Laon. Cotte. 



Copenhagen. Bugge. Padua. Toaldo. 



Mannheim. Hemmer. 



Prague. Strnad. 



Berlin. Beguelin. 



Stockholm. Nicander. 



St. Petersburg. Euler. 



Berlin. Beguelin. 



Stockholm. Nicander. 



St. Petersburg. Euler. 



St. Petersburg. Euler. 



Stockholm. Nicander. 



Sagan. Preus. 



Mannheim. Koenig. 



Sagan. Preus. 



Sagan. Preus. 



Cambridge. Wigglesworth. Lovering. 



Jena. Zeissing. Mannheim. Koenig. 



Copenhagen. Bugge. Prague. Strnad. 



Middleburg. Van de Perre. Sagan. Preus. 



Stockholm. Nicander. Spydberg. Wilse. 



Delphi? Van Swinden. Laon. Cotte. 



Rochelle. Seignette. 



Spydberg. Wilse. Stockholm. Nicander. 



Spydberg. Wilse. 



Spydberg. Wilse. 



Spydberg. Wilse. 



Spydberg. Wilse. 



Cuba. Poey. 



Cambridge. Wigglesworth. Lovering. 



New Haven. Stiles. Loomis. 



1 Journ. des Savans, 1785, p. 243. 



2 Journ. dePhys. XXIV. 399. 



