The Auroral Arch of March 20, 1865, as seen in Ireland. 383 



caused by a magnificent auroral arch, commencing west of the 

 constellation Taurus, rising to a great height, though not 

 actually to the zenith, and terminating close to Arcturus, at a 

 few degrees over the eastern horizon. 



Its shape was of an extraordinary regularity, like a broad 

 path of white light, and it was so intensely visible, and so 

 sharply defined, that it occurred to me to compare it to the 

 brazen meridian of a globe, realized as a luminous band. I 

 viewed it at first with feelings not unmixed with alarm, yet 

 more with deep admiration ; then the thought, ' c It will soon 

 fade away/' led me to make the attempt to look at it with 

 calmness, and note some points to impress on the memory. 



But "look at it" is scarcely the expression to use. It 

 was so large, the eye could not view it as a whole, but pro- 

 gressively, by following it along its sweep of a hundred and 

 forty degrees. 



It remained visible during about half an hour from the time 

 when I first caught sight, of it. When it disappeared, I began 

 at once to write down what I had observed, and marked its 

 place with black paint on the celestial globe. The notes made 

 were to the following effect : — 



"When I first saw it, its left margin (southern) was much 

 brighter than its right, especially at the western extremity, that 

 is, near Taurus. Its breadth there was greatest, viz., about 8°. 

 On turning round quickly and directing attention to the eastern 

 end, that is, near Arcturus, I could observe it was narrower 

 there, but could not trace any appearance of narrowing by 

 carrying the eye along the arch from the western to the eastern 

 end, as its sides then appeared to be parallel to each other. 

 The general stillness of the arch was remarkable ; there were, 

 however, slight exceptions. A distinctly-marked dark cleft 

 appeared in it, running up its centre lengthwise from the 

 western end, to about its highest point. This cleft soon be- 

 came less marked, seeming to close up abruptly. Another 

 movement was to be observed for a few moments along the 

 whole arch, its outline appearing waved, and again resuming 

 its straightness. My view of the western end was impeded 

 by the tops of trees ; nevertheless, I have a distinct impres- 

 sion that it terminated very near the Hyades. The other 

 end was in full view. It just passed Arcturus, and re- 

 mained quite fixed there, the only change being that a 

 small faint streak extended from this extremity to the 

 horizon for a few moments, but quickly faded. This fixed- 

 ness of position was by no means the case with the western 

 extremity, for the arch, during its whole visibility, moved 

 bodily at that end from a position close to Aldebaran to one 

 close to Bellatrix in Orion. I mean that the right or north- 



