Mr. Key's Account of | 
That which I faw on the 12th of April, and which appeared 
like a range of bright yellow clouds, continued fixed for a 
confiderable time, though apparently formed by the comoi- 
natioti of fome corufcations, which a little betore had been 
moving with rapidity. Befides, though there were no co- 
rufcations obfervable in the arches which I law in March, 
yet all of them, except the imperfect one, were perpetu .lly 
varying in the intenfity of their light ; a circumftance which 
fometimes takes place in the aurora boreal.*, when little or no 
(hooting motion can be perceived. 
Mr. Swinton obferved in the white arch, ieen by him in 
1764, an appearance which approaches (fill nearer to that of 
the common aurora. “ An internal undulating motion or the 
“ the particles conftituting the luminous matter, w-hich w as 
“ difcernible from the firft to the laft moment of its exij - 
“ ence” And Dr. Huxiiam deferibes an appearance in the 
luminous arch feen by him, Feb. .5, i 7 5 ^ which approaches 
{fill nearer to that of the aurora borealis. “ Near the top ot 
“the arch, feveral very lucid, white, fliort, vibrating co- 
“ lumns were attached to it” at right angles, as appears by 
the annexed drawing, fome of which were tix or feven degrees 
in length. But the appearance of the arch which Haw the 
1 2th of April would,, in my opinion, have precluded or 
removed all doubt in any fpedator with regard to the nature ot 
this phaenomenon. . . , , 
The luminous arches which 1 have feen exhibited a pleafing 
diverfity with refpeft to their motion ; lome of them having 
none other than fuch as refulted from a varying intent icy or 
their livht, or an internal undulation } others moving .wwly 
and equably in all their parts; and others feeming to conlm ot 
united corufcations, or emitting the moft vivid dalhes or co- 
loured light. 
Thp 
