184 PROCEEDINGS OF THE AMERICAN ACADEMY 



utes latei*, although the sky was clear. A quarter of an hour after, 

 the sky was overcast with dense vapors, which continued for nearly an 

 hour. 



At 1 P 0™ the sky had cleared up, and the moon shone brightly. 

 The luminous appendage was still visible, and even appeared more 

 brilliant than before. In order to ascertain whether this appendage 

 was visible only on one side of the moon, or if it was seen on the 

 other side, I went under the piazza of my house, and placed myself in 

 such a position as to have the moon concealed by its upper part, the 

 sky below beiug visible. As I expected, a similar appendage was 

 observed on the eastern side of the moon, exactly opposite the west- 

 ern one ; the axis of both wings, passing through the moon's centre, 

 being in the plane of the ecliptic. 



Although at this moment no auroral light was seen in the north, 

 yet up in tlie zenith there were evident signs of it, as luminous vapors 

 assembled there and rapidly dissolved, arranging themselves into bands 

 radiating from a centre after the manner of the crown of bright 

 auroras. At ll*" 20", all traces of the luminous vapors in the zenith 

 had vanished ; and at the same time the appendages of the moon were 

 almost totally invisible, although the sky remained clear. 



The fact that the zodiacal light had been unusually brilliant during 

 this evening, and that the two luminous appendages of the moon re- 

 sembled it in shape and appearance, and were situated in tlie same 

 plane, seems to indicate that the two phenomena are of the same order; 

 while the magnetic perturbation and the auroral phenomena connected 

 with the variation of brightness observed in the moon's appendages 

 would seem to indicate some kind of connection between the zodiacal 

 light and the aurora. The result of my observations of the zodiacal 

 light and the aurora during the last seven years also seems to indicate 

 some such connection ; as, when the zodiacal light was observed to be 

 particularly bright, it has generally been followed by auroral phenom- 

 ena. But only a long series of observations in this direction can solve 

 the problem. 



Cambbidge, Nov. 2, 1877. 



