286 Aurora Borealis of November 14, 1837. 
It is stated by M. Wartmann, of Geneva, in the Bibliotheque 
Universelle for October, 1836, that “an illustrious philosopher, 
M. Arago, has often announced in advance, the early appearance 
of an Aurora Borealis; being apprised of its approach by the ex- 
traordinary oscillations of the magnetic needle, which is regularly 
observed every day at the Royal Observatory of Paris; and that 
the event has confirmed his prediction on the same day, though 
frequently the phenomenon has occurred at such a distance as not 
to be observable at Paris.” It would hence appear, that auroral 
action has been detected during the day, by the aid of the needle: 
and it is quite probable that the light would also have been 
observed in the absence of the sun. 
Although the Aurora undoubtedly manifests itself, on many 
occasions, contemporaneously in places situated in every direction 
from the pole, there is no reason to believe that its intensity is, in 
the same latitude, every where the same at any given moment; 
nor that its successive fits come on, or reach their height, in dif- 
ferent longitudes precisely at the same time. There is great rea- 
son, however, for the contrary opinion ; as is manifest, indeed, 
from the various accounts which we have condensed in the pres- 
‘Nor does it seem that the disturbing influence of the Aurora 
upon the magnetic needle is similar in different longitudes. There 
are three observations, of the four recorded in the extract above 
cited from Loudon’s Magazine, which we are able to compare 
with corresponding observations made in New Haven. After ma- 
king ample allowance both ways, for possible errors in time, We 
are able nevertheless to say with positiveness, that, while the nee 
dle in New Haven was deflected to the east; in Brookfield, neat 
Manchester, its disturbance was in the contrary direction ; sess 
ordinary variation in both places being westward. 
Not only are the causes of the Aurora as yet a sealed book to 
us, but we have not been able to ascertain, otherwise than con- 
jecturally, the altitude of the illuminated substance above the 
earth’s surface. {[t is even a question whether this substance is 
within or beyond the limits of the atmosphere. The question is 
one which it is exceedingly difficult to settle. To identify posi- 
tively, particular beams seen from different situations, is not 5? 
simple a matter as it may seem. The same beams observed from 
different points of view, may present very different phases ; while 
