Mr. W. Pringle on the cofilinuance of a Solar Spot. 49 



joined. On the eastern margin of this nucleus, or rather on 

 the interior edge of the penumbra trenching on it, I may 

 mention, a singular patch of a half-burnished colour which 

 attracted my attention after the spot had passed the sun's 

 centre, and for several succeeding days. It was not like 

 those white or bright stellar appearances sometimes seen, and 

 of which there were also at the same time several scattered 

 over the general shallow or shaded space ; it rather resembled 

 some dim, distant fire, seen through a foggy atmosphere at 

 night; and I thought at times that I could detect a gradation 

 of tints from reddish-orange to yellowish-green. It partook 

 so much of a certain lustre, that I imagined at first that it was 

 in the glass. But it was not. Could the electric principle 

 have had any part there? or was the lurid reflexion merely 

 the result of a particular fusion of the luminous and nebulous 

 matter; different in degree though not in kind to that which 

 is thought to occasion the stellate specks ? The large nucleus 

 alluded to became latterly enveloped in a partial penumbra of 

 its own, of the usual smooth and comparatively clear surface, 

 though still involved in and connected with tl»e darker dis- 

 coloured base, or ground of the entire spot. 



Another large round nucleus became formed by the combi- 

 nation of the small ones on the eastern side of the spot before 

 its disappearance at the end of September, which circumstance 

 at the time gave some reason to suspect the possibility of the 

 united group breaking up into two distinct spots, as in August. 

 Nor wassuch a metamorphosis even improbable; and from some 

 observations made in July I am much disposed to consider that 

 it had previously undergone a similar one. Among some 

 memoranda made during the latter month, I find a notice of 

 a spot or cluster which was seen by the naked eye on the 29th 

 and 31st of July, consisting of one large spot, with well-defined 

 nucleus and umbra, closely connected with an extensive com- 

 pact group of minute nuclei imbedded in a dusky penumbra. 

 A rough detached draft represents this spot somewhat ad- 

 vanced past the centre of the sun, going westwards, though 

 the exact date of the drawing is not given underneath. As it 

 was evidently somewhat past the centre, it could not have been 

 more than six days from its disappearing. Taking the time 

 from the 30th of July, the intermediate day, this would give 

 the 6th of August for its passing the western edge of the sun, 

 and the 19th of August for its arrival at the eastern limb, or 

 reappearance. The supplied data must, of course, render this 

 hypothetical, though it is far from being improbable. 



But I am retrograding to the detail of former appearances, 

 which would have been more appropriate in the previous 



Phil. Mag. S, 3. Vol. 34. No, 226. Jan. 1849. E 



