On the Height of the Aurora Borealis. 81 



and Chevallier, in the Athenaeum for November 6 ; by Mr 

 Glaisher, in the philosophical Magazine for the present month ; 

 together with my own observations in the Oxford Herald for 

 October 30, will prove that no calculations founded on the ap- 

 parent altitude of an aui'ora can be depended on ; that Auroral 

 Coronas, Streamers,and Arches are only appearances andoptical 

 illusions ; and that no two observers can see any of these Au- 

 roi'al phenomena at exactly the same time and place, any 

 more than two persons can see exactly the same halo ; or, 

 when looking at the same cloud, can see exactly the same 

 rainbow. There are many discrepancies in these reports, both 

 as regai'ds time and appearances. Professor Chevallier says, 

 " bright streamers, some white, others of a light green, were 

 seen shooting upwards from the northei'n and north-western 

 parts of the sky before half-past six o'clock ; and at intervals 

 a slight crimson flush was observed alternating with the 

 streamers, and diffused over the neighbouring parts of the 

 sky." Mr Glaisher states, that " about 6^ 30™, a bright red 

 streamer was seen to spring up from the north-west ; at 6'^ 40™ 

 another streamer was seen in the north-west ; and at the same 

 time one sprung up from the north, both of which were of a 

 beautiful redT Whilst at Oxford, " about a quarter past six 

 o'clock, a faint red colour overspread the north-Avestern ho- 

 rizon, and at the same time a- slight appearance of Auroral 

 streamers in the north. These appearances continued to in- 

 crease, but more especially the spreading of the glowing red 

 colour, till the north-western sky was covered with large 

 patches, which increased and decreased in size, appeared and 

 disappeared, with a rapidity which was truly surprising; 

 about seven o'clock it became cloudy." 



Professor Chevallier says : " Soon after eight o'clock similar 

 phenomena (to those he before described) were observed ; 

 but the streamers now rose to a greater height, some attain- 

 ing even the zenith, and the rose-coloured tinge of the sky 

 was still tnore rettiarkable." Mr Glaisher takes no notice of 

 any glowing red-coloured patches ; but states, that, from " be- 

 tween 7'' 30'" And 9'' 40'", there were occasional streamers, 

 both red mnl white." Whilst at Oxford, at about eight o'clock, 

 VOL. XLIV. NO. LXXXVII. — .IAN. 1848. P 



