138 



ON THE PERIODICITY OF THE AURORA BOREALIS. 



New Haven f Herrick. Newton and Loomis. 

 Hartford ? Herrick. Newton and Loomis. 

 Gothaab. Block. 



New Haven. Herrick. Newton and Loomis. 

 New Britain. Herrick. Newton and Loomis. 

 Gothaab. Block. Jakobshavn. Rudolph. 

 Gothaab. Block. 



Makerstoun. Broun. Gothaab. Block. 

 Gothaab. Block. 



Albany. Herrick. Newton and Loomis. 

 Christiania. Hansteen. Makerstoun. Broun. 

 Hamburg. Schmidt. 

 Neia York. Hough. Toronto. Sabine. 

 Gothaab. Block. 



New Haven. Herrick. Newton and Loomis. 

 New York. Hough. Jakobshavn. Rudolph. 

 Christiania, Hansteen. Yakoutsk, Kupffer. 1 

 Makerstoun. Broun. Dunse. Stevenson. 

 Gothaab. Block. 

 Gothaab. Block. 



Makerstoun. Broun. Jakobshavn. Rudolph. 

 New York. Hough. 

 Makerstoun. Broun. 

 Gothaab. Block. 

 Gothaab. Block. 



Jakobshavn. Rudolph. Gothaab. Block. 

 Gothaab. Block. 

 Gothaab. Block. 

 Gothaab. Block. 



Makerstoun. Broun. Gothaab. Block. 

 Gothaab. Block. 

 Gothaab. Block. 

 Gothaab. Block. 

 Parma. Colla. 

 Gothaab ? Block. 

 Gothaab. Block. 

 Cambridge. Bond. Lovering. 

 New Haven. Herrick. Newton and Loomis. 

 Gothaab. Block. 

 Gothaab. Block. 

 Jakobshavn. Rudolph. 

 Gothaab. Block. 

 Jakobshavn. Rudolph. 

 Gothaab. Block. 



New Haven. Herrick. Newton and Loomis. 

 New York. Hough. Jakobshavn. Rudolph. 

 Makerstoun, Broun. Dunse. Stevenson. 

 France. Hough. 

 . de 1'Obsery. Phj-s. Centrale de Russie, 1857. Snppl. 



