ON THE PERIODICITY OF THE AURORA BOREALIS. 309 



1819. March 28 ; Sept. 22 (bright from ll h p. m. to 12") ; Oct. 11 (at ll b p. m.), 12- (very bright from 



8 b to ll h P. 51.). 



1820. April 3* (semicircular, from E. to W.). 



1821. Nov. 26-. 

 1823. Feb. 6, 7. 



1827. Aug. 27- (bright), 28- (extremely bright and extensive) ; Sept. 8- (bright), 25 (singular, of a red 

 color, extending to the south and around) ; Oct. 6-, lO, 16*, 18'. 



1828. Aug. 15 (bright) ; Dec. 27. 



1829. Jan. 3> (bright) ; Feb. 4 (bright) ; Sept. 18-, 19-; Dec. 19- (splendid), 22- (splendid bow), 28-. 



1830. Feb. 18> (splendid, and an arc), 21 ; March 4, 29 ; May 15- (splendid) ; Aug. 13- (a light bow), 

 14; Sept. 16-; Oct. 17-. 



1831. March 3-, 8' (brilliant, and a bow). 



1833. July 9 ; Sept. 5- (arc from N. W. to S. E., beautiful), 13- (arch 30°), 14 (arch 10°). 



1835. Nov. 16 (rays brilliant after sunset). 



1836. July 7 (N. E. to S. W.), 15 (N. E. to S. W.). 



1837. Jan. 25- (splendid, extending from N. W. to S. E. in the form of a rainbow. Stars shot forth. It 

 continued some hours, giving the whole earth a red appearance) ; April 6- (splendid, in evening). 



1838. Feb. 21* (bright in evening), 28 (in evening) ; Sept. 13- (arc), 14- (streamers. Arc from E. to 

 W.), 15- (streamers), 16- (some streamers), 20*; Nov. 12- (very brilliant in E.), 14- (arc) ; Dec 20-. 



1839. Jan. 14- (very beautiful, from N. W. to S. E.) ; April 21- ; May 10- ; Aug. 15 (brilliant, N. W. to 

 E. : in evening), 29- (beautiful in N. : evening), 31* (in the evening appeared in N. and N. E. some beautiful 

 auroras); Sept. 4- (most brilliant colors), 5 (brilliant again) ; Oct. 10- (beautiful), 11* (beautiful). 



1840. Jan. 3- (brilliant), 4- (brilliant), 6 (brilliant) ; Feb. 24-. 



1848. Oct. 23- (brilliant), 25- (brilliant), 26-, 27-, 28- ; Nov. 17- (brilliant and partly bright red). 



1849. Nov. 27- (splendid, a red appearance). 

 1857. Sept. 3-. 



TV. Observations on the Aurora, made by Lieutenant C. J. B. Riddell and Captain J. H. Lefroy, at 



Toronto, Canada. 1 



1840. Jan. 3-, 31- ; Feb. 7; 8, 28-; March 5-, 6-, 21-, 25- ; April 1-, 4- ; May 27-, 28?-, 29- ; Aug. 19-, 

 21-, 23-. 24-. 25-, 28* ; Sept. 2-, 16-, 17. 20, 21-. 25-, 27- ; Oct. 19-, 22-, 31- ; Nov. 13- ; Dec. 20-, 23«, 28>. 



1841. Jan. 9. 18-. 24-, 25«, 27- ; Feb. 11-. 12-, 15-. 23-. 24- ; March 11-, 14- ; April 13, 18-, 19-, 21«, 26 ; 

 May 2G- ; June 15- ; July C-, 14, 15, 19-, 21-. 24-. 28-, 30 ; Aug. 6, 11, 14, 22, 23 ; Sept 12-, 13-, 25- ; Oct 

 7-, 8-, 9-, 13-, 15-, 24- ; Nov. 4, 5-, 8-, 18« ; Dec. 14-, 17-. 



1842. Jan. 10, 15-, 29 ; April 10-, 11', 14-, 15-; June 4-, 14; July 2?-, 3-, 9-, 11-, 14, 31-; Aug. 5-; 

 Sept. 1. -2; 13-, 15', 16-, 28- ; Dec 5-. 



1843. March 5-, 6- ; April 5-, 6- ; June 30- ; July 2-, 7; 25-, 26 ; Aug. 3- ; Sept. 18-, 20-, 21-, 27-, 29- ; 

 Oct. 19-; Dec. 11-. 



1844. Jan. 24-, 28- ; March 2-, 7; 9- ; April 16-, 18- ; May 7; 8; 14-, 22- ; June 20'; July 8« ; Aug. 9», 

 29* ; Sept 14-, 19-, 30?- ; Oct 20- ; Nov. 13-, 16-?. 



1 From the manuscripts of Captain (now General) Lefroy. 



