[2] 1 kilometer = 0.6214 mile; 100 kilometers may be taken as 62 miles. 1 kilogram is about 2.2 lb.; 5 kilograms = 11 lb.—Translator.

[3] It is useful to know the letters of the Greek Alphabet. They are easily learned, as follows:

a Alpha
Beta
? Gamma
d Delta
e Epsilon
? Zeta
? Eta
? Theta
? Iota
? Kappa
? Lambda
Mu
? Nu
? Xi
? Omicron
p Pi
? Rho
s or ? Sigma
t Tau
? Upsilon
f Phi
? Chi
? Psi
? Omega

[4] All the stars visible at any hour during the year can easily be found with the help of the author's Planisphere mobile.

[5] Let it be remarked in passing that the stars might be much farther off than they are, and invisible to our eyes; the Heavens would then assume the aspect of an absolutely empty space, the moon and planets alone remaining.

[6] 14 = 14 seconds of arc. One second of the circle is an exceedingly minute quantity. It is 1 millimeter seen at a distance of 206 meters. One millimeter seen at a distance of 20 m. 62 = 10 secs. These values are invisible to the unaided eye.

[7] These fine double stars can be observed with the help of the smallest telescope.

[8] For the explanation of the angular distances of degrees, minutes, and seconds, see Chapter XI, on Methods of Measurement.

[9] The author has endeavored on the plates to represent the aspect of the Earth in the starry sky of Mercury, Venus, and Mars; but in all representations of this kind the stars are necessarily made too large. By calculation the diameters of the Earth and Moon as seen from the planets, and their distances, are as follows:

These aspects will be appreciated if we remember that the distance of the components of e Lyre = 207, that of Atlas in Pleione = 301, and that of the stars Mizar and Alcor = 708.

[10] A few evenings ago, after observing Venus in the calm and silent Heavens at the close of day, my eyes fell upon a drawing sent me by my friend Gustave Dore, which is included in the illustrations of his wonderful edition of Dante's Divina Commedia. This drawing seems to be in place here, and I offer my readers a poor reproduction of it, taken from the fine engraving in the book. Dante and Virgil, in the peaceful evening, are contemplating lo bel pianeta ch'ad amar conforta (the beautiful planet that incites to love).

[11] Strictly speaking, 1 kilometer = 0.6214 mile. Here, as throughout, the equivalents are only given in round numbers.—Translator.

[12] Translator: Compare the well-known English rhyme:
Thirty days hath September,
April, June, and November.
While all the rest have thirty-one,
Excepting February alone,
In which but twenty-eight appear
And twenty-nine when comes Leap Year.

[13] Fifty-eight different pictures of the aspect of the Moon to the unaided eye will be found in the Monthly Bulletins of the Astronomical Society of France, for the year 1900, in pursuance of an investigation made by the author among the different members of the Society.

[14] My readers are charged not to speak of this property (which is fairly extensive), lest the Budget Commission, at the end of its resources, should be tempted to put on an unexpected tax. This ring, which the astronomers presented to me in the year 1887, is almost in the center of the lunar disk, to the north of Ptolemy and Herschel.

[15] "La fin du Monde." Flammarion, p. 186.

[16] Victor Hugo. Tristesse d'Olympia.