226 AURORA BOREALIS. 



criminately iu one catalogue all the auroras reported from any part of the world, 

 and thus incorporating occasional lists embracing, perhaps, one or two years' 

 observations from polar regions where auroras are seen almost every clear night, 

 the total number of auroras for the different years exhibits an inequality not 

 due to any real change in the frequency of .auroras, but rather to a change iu 

 the place of observation. I have, therefore, sought to obtain, as far as possible, 

 continued series of observations from single localities. In this I have been but 

 partially successful, but think the data are sufficient to warrant some important 

 conclusions. The following table embraces several such partial lists, and ex- 

 tends from 1685 to 1864. 



The column marked 1 is taken from a catalogue of auroras seen throughout 

 Europe, as collected by Mairan in his Traite de I'Aurore Boreale, 2d ed., 

 pp. 552-554. 



The column marked 2 contains the auroras observed in Sweden, chiefly at 

 Upsala and Christiania, latitude 59"^ 52' or 54'. The observations from 1716 

 to 1733 are given in Mairan, p. 497. The observations from 1739 to 1762, and 

 from 1S46 to 1853, are from the Bulletin de I'Acaderaie R. de Belgique, t. 21, 

 pp. 284-300 ; those from 1837 to 1846 are from the Metnoires de I'Acad. R. de 

 Belgique, t. 20, p. 117; and the remaining observations are from Wolf's Vier- 

 teljahrs Schrift, 1863, p. 108. 



The column marked 3 contains the auroras observed at St. Petersburgh, lati- 

 tude 590 56'. Those from 1726 to 1739 are from Mairan, p. 512. The others 

 have been collected from the successive volumes of the Memoirs of the Academy 

 at St. Petersburgh. 



The cokxmn marked 4 contains a catalogue of auroras observed in different 

 parts of Europe, collected by Ootte, in his Memoires sur la Meteorologie, v. 1, 

 p. 366. 



The column marked 5 contains Dalton's catalogue of auroras as published in 

 his Meteorological Essays, pp. 54-58 and 218-226. The first seven years are 

 for Kendall and Keswick, Scotland, latitude 54"^ 17' and 54^ 33' north. The 

 other observations are for Great Britain generally. The numbers for 1835 and 

 1836 I have added from Bone's catalogue, in order to supply a gap in the series. 



The column marked 6 contains the auroras observed at Mannheim, latitude 

 49° 29', taken from Ephemerides Met. Palatinae, 1781-1792. 



The column marked 7 contains observations at Dunse, Scotland, latitude 

 55° 47', from Phil. Soc. Abstracts, vi, p. 291. 



The column marked 8 contains observations at Makerstoun, Scotland, lati- 

 tude 55° 35', from the Edinburgh Phil. Trans., v. 19, p. 81. 



