1 1 % Don ulloa’s Qbfervations 
ter for reflecting the rays of light, fince otlierwife the 
ring would not have been equally clear, Alining, and co- 
loured throughout the whole circumference of the 
Lunar dilk. It cannot be faid, that this luminous ring is 
the effeCt of the rays of the Sun reflected by the atmo- 
fpliere of the earth, becaufe the apparent diameter of the 
Sun is fmaller than that of the Moon, whofe dilk en- 
tirely hid that of the Sun. Befides, if the luminous cir- 
cle had been made by the atmofphere of the earth, its 
colours would have been like thole of the rainbow, and 
it would have appeared fixed without motion, inftead of 
which, that which was feen is the fame as that which is 
feen by the naked eye upon the Sun when it is juft above 
the horizon a little after Sun-rife or before Sun-fet, fo 
that one may conclude, that this luminous circle is a part 
of the dilk of the Sun feen after refraction through the 
atmofphere of the Moon. 
The 
I’effet des rayons da Soleil reflechis fur l’atmofpherede la Terre, puifque le dia- 
metre apparent du Soleil eft plus petit que celui de la Lune,dont ledilque cachoit 
entierement a nos regard ou a ceux du globe terreftre celui du Soleil. D’ailleurs, 
li cetoit fur l’atmofphere de la Terre que le cercle lumineux fut forme, ce cercle 
auroit ete femblable dans fes conleurs a l’arc-en-ciel, et il auroit paru fixe fans 
mouvement ; au lieu que celui qui a ete aper^u eft le meme qu’on diftingue dans 
le Soleil en le regardant dire&ement avec la fimple vue fur l’horizon peu apres foil 
lever ou un peu avant fon coucher : enforte qu’on peut conclure que ce cercle 
lumineux eft une partie du difquedu Soleil vu par refradlion fur l’atmofphere de 
la Lune. 
