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spot, iii which the secondary penumbra had been plainly 
visible, and had been observed by him to consist of a fine net- 
work of bright lines. The penumbra was strikingly striated, 
and the middle of the nucleus had been occupied by a bright 
spot detached from the penumbra at first, but afterwards 
joined to it, as the spot began to close up, by one of the pro- 
jecting spurs usually observed to occur in decaying spots. 
For the purpose of the observations a trough filled with 
sulphate of indigo was placed in the cone of rays coming from 
the large mirror of a Newtonian reflector of seven inches 
aperture, before they reached the eyepiece. The sun’s image 
was a deep red colour, but the definition was very good. 
Professor Clifton suggested that the unusual visibility of 
the secondary penumbra in this case might arise from its being 
so coloured as to be rendered more visible than usual by the 
use of the sulphate of indigo. 
June 27th, 1861. 
Mr. Baxendell read a Paper entitled “ Observations of 
Comet I, 1861.” [This Paper was afterwards read at the 
Ordinary Meeting of the Society, held on the 1st October, 
1861.] 
Mr. Baxendell also read a note “ On a Solar Spot of 
Long Duration.” 
At the last meeting of the Section I exhibited a sketch 
made on the 24th April, 1861, of a solar spot in which the 
secondary penumbra had been seen with unusual distinctness. 
This spot has since twice crossed the visible disk of the sun, 
and has had a term of existence considerably above the ordi- 
nary average. It was first seen on the 17th of April, near 
