II. 



On the Periodicity of the Aurora Borealis. 



BY JOSEPH LOVERING, 



HOLLIS PROFESSOR OF MATHEMATICS AND NATURAL PniLOSOFIIT IN HARVARD COLLEGE. 



Communicated, December 6, 18G4. 



The object of this memoir is to present a catalogue of auroras from the earliest 

 observed down to the present epoch, and upon this catalogue, as a foundation, to recon- 

 struct the laws of periodicity of the phenomenon. For the observations prior to 1750, 

 I am indebted, principally, to Mairan's first and second catalogues ; the latter itself being 

 compiled, for the most part, from numerous smaller catalogues existing in his day. 1 I 

 have introduced, however, many additional observations in high latitudes, ruled out by 

 Mairan, in accordance with the plan of his work; as well as some old auroras brought 

 to light by the investigations of Quetelet, Boguslawski, and Chasles, or by my own 

 researches. 



For the last century I have used the following materials : 390 auroras observed at 

 Cambridge, Mass., between 1742 and 1793 by Winthvop or Wigglesworth ; 316 auroras 

 observed at the same place, between 1840 and 1864, by W. C. Bond or G. P. Bond or 

 myself; 36 auroras observed at Boston, Mass., between 1818 and 1840, by Hale; 198 

 auroras observed at Salem, Mass., between 1786 and 1820, by Holyoke : — all published 

 first by myself. I have also compiled, from their original places of publication, 212 

 auroras observed at Worcester, Mass., between 1839 and 1862, by Woodward, Chandler, 

 or Bemis; 160 auroras observed at Providence, R I., between 1832 and 1860, by Cas- 

 well ; 74 auroras observed at Burlington, Vt., in 1852 and 1853, by Thompson ; 89 



1 Mairan's first catalogue consists of 229 auroras. His second catalogue of 2137 observed auroras, of which 1441 are inde 

 pendent of each other, comprises Frobes's catalogue of "96 auroras observed between 583 and 1739. To these are added Deliste's 

 catalogue of 233 auroras observed at St. Petersburg between 1 726 and 1 736 ; Celsius's catalogue of 384 auroras observed in Sweden 

 between 1716 and 1732; Kirch's catalogue of 106 auroras observed at Berlin between 1707 and 1735 ; Weidler's catalogue of 91 

 auroras observed at WiUemberg between 1730 and 1751; the catalogue of Zanoiti and Beccari which contains 88 auroras, 

 observed in Italy between 1727 and 1751 ; Short's catalogue of 148 ancient auroras ; Kirch's catalogue of 89 auroras observed 

 between 1549 and 1657 ; and 202 auroras compiled by Mairan himself from the Transactions of the Royal Society of Loudon. 

 VOL. X. 2 



