Mr William Sturgeon on the Aurora Borealis. 151 



arch, by admeasurement, never exceeded 12° of altitude; its high- 

 est point being close upon the magnetic north of this place. Its 

 horizontal span was about 105°, but, in consequence of the diffused 

 character of the light constituting this principal f.ature of the aurora, 

 these dimensions ^can only be considered as close approximations to 

 the truth. Before nine o'clock, dense clouds shrouded the aurora 

 from view, and as the sky soon became covered with clouds, the spec- 

 tacle closed for the night. I had a magnetic needle delicately sus- 

 pended by a single fibre from the cocoon of the silkworm, which was 

 closely watched,\t every opportunity, during the whole time ; about 

 half-past seven it became slightly agitated, but made not any excur- 

 sion either eastward or westward ; its motion being a mere noddmg 

 in a vertical plane, which was continued for some time, probably 

 much longer than the cause continued to operate upon it, as is al- 

 ways the case when needles are thus delicately suspended. 



The next grand appearance of the aurora borealis was on Friday 

 night, 17th November. A strong south wind with heavy rain began 

 about six in the morning, and lasted till ten in the forenoon, about 

 which time the wind veered westward until it arrived at north-west ; 

 and the rain cleared away. The wind still continued high ; the 

 thermometer was 50°. Slight showers towards evening, and the 

 night was introduced by the most extensive aurora borealis I had 

 ever beheld. 



It began with the close of day, and lasted all night. I observed 

 till twelve o'clock, at which hour, though cloudy, and scarce a speck 

 of clear sky to be seen, the whole canopy was illuminated by the 

 aurora ; and the light generally, even in the southern regions of the 

 heavens, was much stronger than that afforded by a «/iMi?j/-clouded 

 full moon. 



I was in Manchester at the time of its commencement, and had 

 no opportunity of seeing it till after my arrival at Prestwich, by the 

 omnibus, about a quarter before eight o'clock. At that moment my 

 attention was attracted by the unusual glare of light, and on lookmg 

 up, I perceived immense floods of streamers flowing in almost every 

 direction, and on every side excepting the south, which appeared 

 totally devoid of them, though strongly illuminated. The cast and 

 west parts of the heavens appeared the most luminous of the whole, 

 although all around the north was in a blaze of hazy streamers ; in- 

 deed, every part of the aurora appeared as if composed of illuminated 

 aqueous vapour, distributed in various forms in different parts of the 

 circumambient aerial space. From the east, round by the north, to 

 the west, these streamers appeared to flow upwards, in the usual 

 way ; but in the zenith, all about that point, they arranged th.ni-^ 

 selves directly across the meridian ; and on both lings of this line of 

 streamers, and southwards, the auroral light consisted of fine, steady 

 blushes, without any attendant streamers whatever. 



Light fleecy clouds were passing over, with a brisk NW. wind sit 



