258 



nation amounted to53'.8, while the change of the horizontal 

 force was .004. At the time of this observation, the sky was 

 overcast with light fleecy clouds; but in the course of the 

 evening the aurora was seen. 



The following additional notes were furnished by Mr. 

 Bergin. 



"The aurora was first seen about half past five o'clock 

 p. m. as a luminous arched bank, on the N. W. horizon, 

 extending about 30° horizontally, and having a versed sine of 

 about 15° vertical, with occasional very thin, luminous, cloud- 

 like patches, stretching to the zenith. It was some mi- 

 nutes before I could be certain, whether it was aurora or 

 only vapoury clouds. About half an hour afterwards, there 

 was a very well defined luminous arch over the bank, and 

 parallel to it, perhaps 10° higher, with motionless stream- 

 ers from the bank towards the arch. From the summit of the 

 latter there sprung a vertical arch, (very faint,) which ex- 

 tended nearly to the zenith, where there was a faint circu- 

 lar patch (corona ?) 



" The space between the bank and the horizontal arch 

 was intensely dark ; yet that the darkness was not caused 

 by clouds, was evident, as a few stars were distinctly visible 

 within this space. At this time there was a very remarka- 

 ble brush of light, commencing apparently at the centre star 

 of Orion's belt, diverging southward for 10° or 12°, and 

 slightly inclined upwards : this brush was perfectly motion- 

 less, and remained altogether unchanged during an interval 

 of five minutes or thereabouts ; my attention was then for a 

 short time directed to the arch, and when I again looked 

 towards Orion, the brush had entirely disappeared. 



" About nine o'clock, the horizontal and vertical arches, 

 as well as the coronal patch, had quite disappeared; or 

 rather they had united with the bank first described. 



" At half past ten the appearance had again changed, 



