343 



from various places where it had been observed in England and in 

 Scotland. It appears to have been actually seen in places 170 miles 

 distant from one another, in a north and south direction, and 45 

 miles distant from east to west, thus comprising an area of 7000 or 

 8000 square miles ; but it must have been visible over a much greater 

 extent. Accounts were received of its having been seen as far north 

 as Edinburgh, and as far south as Manchester and Doncaster, and at 

 most of the intermediate towns ; and from the exact correspondence 

 of the descriptions from all these places, it was impossible to doubt 

 that they referred to the same luminous appearance. In proceeding 

 from north to south, the apparent altitude of the arch continually 

 increased, still keeping to the south of the zenith till we come to 

 Kendal, at which place it, very nearly crossed the zenith ; at War- 

 rington, which is further south, the culminating point of the arch 

 was north of the zenith. Wherever seen, the arch always seemed 

 to terminate nearly in the magnetic, east and west, at two opposite 

 points of the horizon. 



The observations, in which the author places the greatest confi- 

 dence for determining the height of this aurora, were those made at 

 Whitehaven and at Warrington, places which are distant 83 miles 

 from one another, and situated nearly on the same magnetic meri- 

 dian. Calculating from the data they afford, he finds the height of 

 the arch very nearly 100 miles above the surface of the earth, and 

 immediately over the towns of Kendal and of Kirkby- Stephen. This 

 conclusion is corroborated by observations at Jedburgh ; but if the 

 former be compared with those at Edinburgh, the height will come 

 out to be 150 or 160 miles, and the position vertical about Carlisle : 

 but he thinks the former result more entitled to confidence. Assu- 

 ming the height to be 100 miles, it will follow that the breadth of the 

 arch would be 8 or 9 miles, and its visible length in an east and west 

 direction from any one place would be about 550 miles. The author 

 then proceeds to take a comparative view of the results of inquiries on 

 the height and position of other aurora which have at different times 

 appeared, and are recorded in the Philosophical Transactions and other 

 scientific journals. He also gives an account of a luminous arch seen 

 both at Kendal and at Manchester on the 27th of December last, which 

 appeared in the zenith at the former place, and was elevated 53 from 

 the north at the latter place ; whence its height is deduced to be 

 100 miles. From the general agreement of this series of obser- 

 vations, the author infers that these luminous arches of the aurora, 

 which are occasionally seen stretching from east to west, are all 

 nearly of the same height; namely, about 100 miles. Observations 

 are still wanting for the determination of the length of beams parallel 

 to the dipping-needle, which constitute the more ordinary forms of 

 the aurora borealis ; neither can it be determined whether these 

 beams arise above the arches, as from a base, or whether they de- 

 scend below, as if appended to the arches. It is remarkable that the 

 arches and beams are rarely, if ever, seen connected together, or in 



