Solar Eclipse of July 8th, 1842. 177 
telescope, is red or green. These irregularities, as seen by many, 
have been minutely described by Francis Baily, Esq: of London, 
in anarticle in the tenth volume of the Memoirs of the Astro- 
nomical Society, although it particularly relates:to the appearan- 
ces, observed by hiesself, in the south part of. Scotland, during 
the eclipse of May 15th, 1836, which was annular there.. Many 
of the appearances ddscrituea by Mr. Baily, were seen through’a 
red glass at the second and third contacts of the eclipse of Feb. 
12th, 1831, which was annular in the southeastern part of this 
State. Shortly afterwards, however, it having been ascertained 
| | that-a double screen, composed of one light red and one light 
gteen glass, would not only render the light of the sun very: 
pleasant to the eye, but would far better define the limbs, and 
would sometimes ‘even enable me to see a small spot, that was 
invisible throngh the dark red alone, a screen of that kind was 
adapted to the telescope, and was used for the partial eclipses of 
= 1832.and 1836, and those that were central in 1834 and 1838. 
| : _ Through this screen no one of the irregularities described by 
2 Mr. Baily, has ever been perceived, although carefully looked for. 
Indeed so remarkable was the difference between the observed 
: and expected appearances of the sun’s limbs at the second and 
third contacts at Beaufort, S. C. on Nov. 30th, 1834, that even 
, then, asuspicion was excited that the entire absence of all distor- 
tion or ‘irregularity in the cusps, just before and after the total 
obscuration, was to be attributed to the color-of the screen ; espe- 
cially since other observers in the vicinity of Beaufort saw hirotiphe 
red screens, many of most of the usual phenomena. ‘This suspi- 
cion was strengthened by the observations on the large but not 
deipialceclipse « of May, 1836; it was therefore communicated to 
several of our astronomers, who paid particular attention to it, at 
the formation and rupture of the ring on Sept. 18th, 1888, In 
Philadelphia and its vicinity there were many observers, provided 
with telescopes of nearly equal optical capacity, but protected by 
screens of different colors: ‘The result appears to be, that in every, 
or neatly every instance in which the red glass was used, many 
or all of the usual irregularities were seen, whilst those observers 
who used yellow or green screens, saw these appearances either 
greatly modified or not at all. At Princeton, near the northern 
boundary of the ring, two skilful astronomers, provided with fi 
~ feet telescopes by Dollond and Fraunhofer, were enabled dis- 
Vol. x11, No, 1.—Oct.-Dec. 1841. 
