255 



formed, the lower limb of which was beautifully defined. 

 The remarkable feature in this phenomenon was the intense 

 blackness of the sky beneath the arch, as contrasted with 

 that exterior to it. The darkness of this space was such, 

 as to resemble a dense cloud, fringed by the auroral hght ; 

 and the doubt was suggested, whether the dark cloud noticed 

 by many observers, in connexion with aurora, may not have 

 been an appearance of the same kind, though less regular in its 

 outHne. In the aurora of the 19th, the blackness of the 

 space enclosed by the arch was certainly not due to the 

 presence of a cloud, for the stars were distinctly visible in it. 

 Mr. Lloyd stated, that he was so much interested in this 

 part of the phenomenon, as to lose the opportunity of ob- 

 taining a measure of the altitude of the arch. 



Soon after 10 o'clock, the arch began to break up into 

 streamers. Its appearance at this period was such as is 

 represented in the subjoined sketch. , 



From this time, until half past eleven o'clock, Mr. Lloyd 

 took no notes of the appearances, having been engaged in 



z2 



