ON THE PERIODICITY OF THE AURORA BOREALIS. 303 



LX. AURORAS OBSERVED AT HELSINGFORS, ARRANGED BY YEARS AND MONTHS. 



* Continued from page 18-1. 



t This table contains the auroras observed at Abo, from 1748 to 1828 ; and at Ilelsingfors, from 1829 to 1843. 

 by G. G. Hallstrom in Acta Soc. Sci. FennictB, III. Mb. 



Sec Memoir 



