188 ANNUAL OF SCIENTIFIC DISCOVERY. 



spots not black but luminous. These have been called faculae, others 

 of much smaller dimensions and generally round, have been called 

 lucules. These latter cause the surface of the sun to appear spotted. 

 It is a singular fact; but I may trace the origin of the discovery of the 

 facula? and lucules, to an administrative visit to a shop of novelties on 

 the Boulevards. " I have to complain," said the master of the estab- 

 lishment, " of the Gas Company ; it ought to direct on my goods the 

 broad side of the bat- wing burner, whilst, by the carelessness of their 

 servants, it is often the edge which is directed on them." " Are you 

 certain," said one of the assistants, " that in that position the flame 

 gives less light than in the other ?" The idea, appearing ill-founded, 

 and I would say, absurd, it was submitted to accurate experiment ; and 

 it was determined that a flame sheds upon any object as much light 

 when it illuminates by its edge as when its broad surface was presented 

 to it. Thence resulted the conclusion, that a gaseous incandescent 

 surface of a determined extent is more luminous when seen obliquely 

 than under perpendicular incidence. Consequently, if, like our atmos- 

 phere, when dappled with clouds, the solar surface presents undulations, 

 the parts of these undulations which are presented perpendicularly to 

 the observer, must appear comparatively dim, and the inclined portion 

 must appear more brilliant ; and hence every conic cavity must appear 

 a lucule. It is no longer necessary in accounting for these appear- 

 ances, to suppose that there exists on the sun millions of fires more 

 incandescent than the rest of the disc, or millions of points distinguish- 

 ing themselves from the neighboring regions by a greater accumula- 

 tion of luminous matter. 



After having proved that the sun is composed of a dark central 

 body, of a cloudy-reflecting atmosphere, and of a photosphere, we 

 should naturally ask if there is nothing besides. If the photosphere 

 terminates abruptly and without being surrounded by a gaseous atmos- 

 phere, less luminous in itself, or feebly refracting ? Generally, this 

 third atmosphere would disappear in the ocean of light with which the 

 sun always appears surrounded, and which proceeds from the reflec- 

 tion of its own rays upon the particles of which the terrestrial atmos- 

 phere is composed. A means of removing this doubt presented itself; 

 it was selecting the moment, when, during a total eclipse, the moon 

 completely obscures the sun. Almost at the moment when the last 

 rays emanating from the margin of the radiant orb, disappeared tinder 

 the opaque screen formed by the moon, the atmosphere, in the region 

 which is projected between the moon, the earth, and the neighboring 

 parts, ceased to be illuminated. In all our researches upon solar 

 eclipses, innumerable unexpected appearances invariably present 

 themselves ; thus the observers were not a little surprised when, after 

 the disappearance of the last direct rays of the sun behind the margin 

 of the moon, and after the light reflected by the surrounding terrestrial 

 atmosphere had also disappeared, to see rose-shaped prominences from 

 two to three minutes in height, dart, as it were, from the circumference 

 of our satellite. Each astronomer, following the usual bent of his 

 ideas, arrived at an independent opinion regarding the causes of 



