28 ON T1IE RECENT SECULAR PERIOD 



Bossckop (lat. G9° 58'), recorded 143 auroras in two hundred and six days. The 

 greatest number recorded in any one year, in the temperate zone, is believed to be 

 75, which is given in the Regents' Report as the number for 1840. The auroral 

 arch of August 28th, 1827, which marked the commencement of the period under 

 review, was the first auroral exhibition seen in the southern part of Ohio, after the 

 settlement of the State; and that of September 3d, 1839, was the first ever seen in 

 Tennessee by the generation then on the stage. 1 On comparing the same latitudes 

 on the eastern and on the western continents, it is found that a far greater number 

 occur on the western continent. Indeed, at the latitudes of Spain and Italy, these 

 exhibitions are seldom seen at all, while in the same latitudes in New England, 

 many usually occur every year ; and, in the State of New York, from 1832 to 1848, 

 inclusive, the number recorded in the Regents' Reports, is 780 — being an average 

 of more than 43 per annum. We have, in fact, many more auroras in New England 

 and New York, than occur in England ten degrees north of us. The greatest 

 number ever recorded by Dalton, in England, in a single year, appeared in 1830, 

 being 30, which was nearly twice the average of auroras from 1827 to 1834, a 

 period which Dalton considers as very extraordinary for these exhibitions, although 

 during this period, the average number, per annum, was 1G; while from 1819 to 

 1820, the average number was only II. According to a record of auroras kept at 

 Deerfield, Massachusetts, by General Field, the average for 1830 and 1831, was 56. 2 

 Although the aurora occurs in the southern hemisphere, yet such evidence as we 

 have, indicates that it is less frequent and less magnificent, than in the northern 

 hemisphere. I have conversed with whalers and others, who have been repeatedly 

 around Cape Horn without ever seeing an aurora australis ; and, although we find 

 in Commodore Wilkes's Narrative of the United States Exploring Expedition, 

 instances described and delineated sufficient to establish the fact of the existence 

 of these lights around the southern pole, yet the number appears to be far less 

 than in corresponding latitudes of the northern hemisphere. In the year 1750, 

 Mairan addressed a note of inquiry respecting the aurora australis to Don Ulloa, 

 the celebrated navigator who carried out the French Academicians to Peru. The 

 reply of Don Ulloa, who was much conversant with the southern hemisphere, is so 

 curious and instructive, that it appears to me worthy of more general notice than 

 it is likely to receive in the old and rare volume where it was first published, and 

 I therefore subjoin the original form, as given by Mairan. 3 



M. C'est avec bien du plaisir que j'ai recu la lettre que vous in' avez fait l'honneur cle lnYerire, du 

 '24 de ce mois, sur les Aurores de 1 'hemisphere austral, dont M. Jallabert vous a parle, d'aprfes l'entretien 

 que j'avois eu avec lui sur ce sujet. Je lui ai dit que j'en avois vu quelques-unes, lorsque le temps 

 etoit favorable, mais non que j'en eusse fait des observations dans tous les formes, comment il auroit et<§ 

 a desirer, parceque le brouillard plus ou moins epais dont notre navire etoit presque toujours enveloppe 

 ne le permettoit pas. C'est la raisou pourquoi je n'en ai point parle dans la relation de mon voyage. 

 Et il est bon que je vous dise a ce sujet, que tout ce que j'ai pu distinguer, lorsque les brouillards se 



1 In this classification of the general facts, we may be permitted to repeat occasionally individual 

 facts which have been mentioned before. 



a Amer. Jour. Sci., XX, p. 272. 3 Mairan, Traite de l'Aur. Bor., p. 439. 



