These were careful and accurate observers, and they could not have been mistaken about a star of the first magnitude. β Leonis is now fainter than an average star of the second magnitude, and there can be no reasonable doubt that it has faded considerably since the Tenth Century. There are some other discrepancies between Al-Sûfi’s observations and modern estimates, but the above are perhaps the most remarkable. With reference to lucid stars not mentioned by Al-Sûfi, he has not, I think, omitted any star brighter than the fourth magnitude in that portion of the sky visible from his station. There are, however, a number of stars between the fourth and sixth magnitudes which he does not mention. Of these the brightest seem to be ε Aquilæ, ρ and μ Cygni, and ζ Coronæ Borealis. With reference to the distribution of the lucid stars in the sky there seems to be a well-marked tendency to congregate on the Milky Way. It is a remarkable fact that of the 15 brightest stars in the heavens, no less than 11 lie on or near the Milky Way, although the space covered by the Galaxy does not exceed one-fifth or one-sixth of the whole sky. From a careful enumeration of the stars in or near the Milky Way which I made some years ago, I found that of stars brighter than the fourth magnitude there are 118 on the Milky Way out of a total of 392, or about 30 per cent. From the Southern catalogue known as the _Uranometria Argentina_, Colonel Markwick, F.R.A.S., found 121 out of 228 stars to fourth magnitude, or a percentage of 53 per cent. These results seem to show some intimate relation between the lucid stars and the Galaxy. FOOTNOTES: [4] Except concave spectacles used by short-sighted persons. [5] This custom has since prevailed. The following are the letters and their names: α Alpha η Eta ν Nu τ Tau β Beta θ Theta ξ Xi υ Upsilon γ Gamma ι Iota ο Omicron φ Phi δ Delta κ Kappa π Pi χ Chi ε Epsilon λ Lambda ρ Rho ψ Psi ζ Zeta μ Mu σ Sigma ω Omega THE CONSTELLATIONS.—CAMILLE FLAMMARION The earth is forgotten, with its small and ephemeral history. The sun himself, with all his immense system, has sunk in the infinite night. On the wings of inter-sidereal comets we have taken our flight toward the stars, the suns of space. Have we exactly measured, have we worthily realized the road passed over by our thoughts? The nearest star to us reigns at a distance of 275,000 times 37 millions of leagues—that is to say, at ten trillions[6] of leagues (about twenty-five billions of miles); out to that star an immense desert surrounds us, the most profound, the darkest, and the most silent of solitudes.