OF THE AURORA BOREALIS. 37 



which are still longer intervals when it is hardly seen in any of its higher forms, 

 I must regard it as a problem of much interest to ascertain the length of these 

 cycles after which a great return of the aurora borealis may be expected, and the 

 number of years it may be expected to prevail. 



The interval from the middle of one secular period to the middle of another, 

 appears, so far as we can judge from imperfect historical data, to be about sixty-five 

 years. Pliny says, " We sometimes see (than which there is no presage of woe 

 more calamitous to the human race) a flame in the sky, which seems to descend 

 to the earth in showers of blood; as happened in the third year of the 107th 

 Olympiad, when Philip was endeavoring to subjugate Greece." He adds, that 

 about the year G41 from the building of Rome, they saw, during the night, a light 

 which shone as the day; that it was nothing uncommon about that time to see the 

 heavens all on fire. He cites examples of those which appeared to meet in conflict 

 from the east and west ; and says that they heard the clash of arms and the sound 

 of trumpets ; and that the heavens themselves were on fire. 1 



Along with the fabulous accompaniments which usually graced such narrations 

 among the ancients, Ave recognize in these statements the middle of one of the 

 great returns of the aurora; nor have the same phenomena, at much later periods, 

 been described without a tincture of the marvellous; for it was the popular belief, 

 at least among the more uneducated classes, during the great auroral period which 

 immediately preceded the one under review, namely, that which covered the time 

 of the American revolutionary war, that conflicts of armies were frequently wit- 

 nessed in the skies. 



About the year 400, historians relate that columns were seen suspended in the 

 sky for the space of three days, and that a fire burned behind a cloud which was 

 terrible for its splendor, sometimes overspreading the sky. 3 Comparing the interval 

 between this period and that described by Pliny, we find that eight periods, of 65 

 years each, would bring us to the year 408, or into the midst of the remarkable 

 exhibition of auroras thus described. 3 In the year 585, occurred the famous aurora 

 recorded by Gregory of Tours, which Mairan considers as resembling the great 

 exhibitions of his time, as that of 1726, most of all those described by the ancients, 4 

 and this would fall in the third return after that which occurred about the year 

 400. In the month of September, 1583, there arrived in Paris, in formal proces- 

 sion, and in the habit of penitents, or pilgrims, eight or nine hundred persons, to 

 present their gifts and ask prayers, on account of signs seen in the heavens, and 

 fire in the air. On comparing this date with the period mentioned by Pliny, which 

 was 112 years before the Christian era, we have an interval of 1695 years, 

 embracing twenty-six periods, of 65 years each. In 1607, November 17th, a great 

 aurora occurred, and is minutely described by Kepler, which greatly resembled our 

 auroras of the first class. Since the aurora of 1583 excited great surprise, it was 

 probably the commencement of the period, and that of 1607 near its close, making 

 the duration 24 years. 



1 Hist, Nat., 1. 11, c. 57. 3 Mairan, p. 1*79. 



3 Building of Rome, B. C. 753; and 753— 611 x 40S=520=8x65. 4 Mairan, p. 181. 



