70 COSMOS. 



red, mountain, or flame-like elevations, which, if not seen for 

 the first time, were at all events more distinctly visible during 

 the eclipse of the Sun of the 8th of July, 1842, when they 

 were simultaneously noticed by several of the most experi- 

 enced observers, have led astronomers to assume the existence 

 of a third envelope of this kind. Arago, in a treatise devoted 

 to the subject,* has with much ingenuity tested the several 

 observations, and enumerated the grounds which necessitated 

 the adoption of this view. He has at the same time shown 

 that since 1706 similar red marginal protuberances have been 

 eight times described on the occasion of total or annular so- 

 lar eclipses.f On the 8th of July, 1842, when the apparently 

 larger disk of the Moon entirely covered the Sun, the Moon's 

 disk was observed to be surrounded not only by a whitish 

 light, i encircling it like a crown or luminous wreath, but two 

 or three protuberances were also seen, as if originating at its 

 margin, and were compared by some observers to red jagged 

 mountains, by others to reddened masses of ice, and again by 

 others to fixed indented red flames. Arago, Laugier, and 

 Mauvais at Perpignan, Petit at Montpelier, Airy on the Su- 

 perga, Schumacher at Vienna, and numerous other astrono- 

 mers, agreed perfectly in the main features of the final re- 

 sults, notwithstanding the great differences in the instruments 

 they employed. The elevations did not always appear simul- 

 taneously ; in some places they were even seen by the naked 

 eye. The estimates of the angles of altitude certainly differ- 

 ed ; the most reliable is probably that of Petit, the director 

 of the Observatory at Toulouse. He fixed it at 1' 45", which, 

 if these phenomena were true sun-mountains, would give an 

 elevation of 40,000 geographical miles ; that is to say, nearly 

 seven times the Earth's diameter, which is only 112th part 

 of the diameter of the Sun. The consideration of these phe- 

 nomena has led to the very probable hypothesis that these 

 red figures are emanations within the third envelope — ?nasses 

 of clouds which illumine and color the photosphere. § Ara- 



# Arago, in the Annuaire for 1846, p. 271-438. 



t Id., Ibid., p. 440-447. 



X This is the white appearance which was also observed in the solar 

 eclipse of the 15th of May, 1836, and which the great astronomer of 

 Konigsberg very correctly described at the time by observing " that 

 although the Moon's disk entirely covered the Sun, a luminous corona 

 still encircled it, which was a portion of the Sun's atmosphere." (Bes- 

 sel, in Schum., Astr. Nachr., No. 320.) 



§ " Si nous examinions de plus pres l'explication d'apres laquelle les 

 protuberances rougeatres seraient assimilees a des nuages (de la troi- 

 6ieme enveloppe),nous ne trouvcrions aucun principe de physique qui 



