REV. JAMES FARQUHARSON ON THE AURORA BOREALIS. Ill 



vei-ified by others ; and it is a fortunate circumstance that those which I have 

 now detailed are almost all incidentally verified by some or other of the many 

 observations collected by Mr. Dalton, although evidently none of these have 

 been made under the impression of those views of the peculiar arrangement 

 of the meteor, which frequent opportunity for observation had opened up to 

 me. I shall briefly point out the verifications. The references are to Mr. 

 Dalton's paper in the Philosophical Transactions. It is unnecessary to refer 

 specifically to the testimonies to three facts, as almost all the observations co- 

 incide regarding them. 1st, That the arch of the aurora, when at the zenith, 

 is placed at right angles to the magnetic meridian : 2nd, That there it is only 

 of small breadth : and 3rd, That it moves southwards. None of the observers 

 appear to have had an opportunity for observing the transition of the vertical 

 streamers from a low northerly situation into the zenith arch ; but Messrs. 

 Coldstream and Foggo at Edinburgh saw, and have well described some of 

 the concluding stages of this transition, and the transformation which the 

 figures and intensity of the lights undergo at the approach to the zenith. The 

 sudden formation of the meteor, only " a few degrees to the north of the 

 zenith," gave them no opportunity for observing the earlier stages. They say ; 

 " When first formed, it" (an arch of silver light) " was a few degrees to the 

 north of the zenith of this place ; the light in the centre was rather diffuse ; its 

 edges were irregular ; and the western limb had, as it were, a plumose appear- 

 ance. It soon evinced a decided motion towards the south, and in a few 

 minutes reached our zenith. Its edges were now sharply defined, and through- 

 out its whole course it was nearly uniform in appearance and breadth ; the in- 

 tensity of light in its zenith had increased, while in the same quarter the 

 breadth had considerably diminished." These terms might be interchanged 

 with the description of this last stage of the transition, given by me in 1823. 



The enlargement of the breadth of the arch after it has passed considerably 

 to the south of the zenith, is verified by the observer at Newton-Stewart : " It 

 was a bow or arch of silvery light, stretching from east to west, and inter- 

 secting the meridian at a few degrees to the southward of the zenith ; after ex- 

 panding a little in breadth and shifting for a short way further to the south, it 

 disappeared." Unfortunately no notice is taken of the breadth of the arch as 

 seen at Jedburgh, 30° and ultimately 50° south of the zenith : but the ob- 



