25S 



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, 



