ON THE SECULAR PERIODICITY OF THE AURORA BOREALIS. 1(»7 



Journal of Meteorology kept at Cambridge by Professor John Winthrop, from 1742 to 

 1779; that of Professor Edward Wigglesworth, kept also at Cambridge from 1782 to 

 1793; and that of Dr. Enoch Hale, kept at Boston, from 1818 to 1848. In all these 

 journals, except the last, the auroras are noted with great care. Dr. Hale, probably, 

 recorded only the most conspicuous. This collection of manuscripts covers more than 

 a century of time, in which only two years are unrepresented, namely, 1780 and 1781. 

 From this rich storehouse of observations, I have been able to cull C24 recorded ex- 

 amples of auroras, of which only 79 are duplicates. After subtracting these, 545 inde- 

 pendent auroras remain, which have never before appeared in print. Of the 624 

 observations contained in all the manuscripts, 254 were registered by Professor Win- 

 throp, 136 by Professor Wigglesworth, 198 by Dr. Holyoke, and the balance (36) by 

 Dr. Hale. As all these observations have been made at places only a few miles apart,* 

 they are strictly comparable with each other, and furnish an almost uninterrupted 

 history of the aurora in this immediate vicinity for a century. It appears from t hese 

 journals, that during the thirty-three years, between 1792 and 1826 inclusive, only 48 

 auroras were observed ; but that during the thirty-three years next preceding 1792, 

 there are registered 387 independent auroras. And even during the eighteen years 



between 1742 and 1759 incl 



far back before 1759 as the observations 



extend), 77 auroras are recorded. And single years may be selected in which there 

 occurred nearly twice as many auroras as in the whole period of thirty-three years, 

 ending with 1826. None were observed in the years 1796, 1797, 1798, 1799, 1800, 



1801, 1807, 1808, 1810, 1811, 1812, 1813, 1816, and 1817. Observations on the aurora, 

 made exclusively in the State of New York,f between the years 1826 and 1850 inclu- 

 sive, exhibit 1152 independent appearances during that period of twenty-five years : 

 and, when combined with those already described, they manifest for this part of the 

 United States what Dalton's observations have demonstrated for England and Ireland, 

 namely, that the displays of the aurora are in a high degree intermittent. 



A study of the sequences in the succession of remarkable auroras may be even more 

 instructive than an indiscriminate attention to all ; for this reason, if for no other, that 

 such auroras can hardly have escaped detection and description in early times. In 

 the United States, great auroras were witnessed on December 17, 1719 ; on October 22 



♦ 



Winthrop's Journal was kept at Andover during May, June, July, and August, at Watertown 



and 



head 



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Obedience to Instructions from the Regents of 



Academies 



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