ON THE PERIODICITY OF THE AURORA BOREALIS. 



255 



1 Nouveau catalogue. Mem. de 1'AcaJ. Brux. XV. 49. 

 - Wolf assigns the aurora of March 23 to March 13. He also 

 has one on Aug. 26. 

 3 Connaiss. de Tern's., 1837, p. 379. 

 « Bibliotheque Universale, Geneva, 1840, XXX. 209. 



