| 1 | Furnerius | 14 | Albategnius | 27 | Arzachel |
| 2 | Petavius | 15 | Hipparchus | 28 | Walter |
| 3 | Langrenus | 16 | Manilius | 29 | Clavius |
| 4 | Macrobius | 17 | Eudoxus | 30 | Tycho |
| 5 | Cleomedes | 18 | Aristotle | 31 | Bullialdus |
| 6 | Endymion | 19 | Cassini | 32 | Schiller |
| 7 | Altas | 20 | Aristillus | 33 | Schickard |
| 8 | Hercules | 21 | Plato | 34 | Gassendi |
| 9 | Romer | 22 | Archimedes | 35 | Kepler |
| 10 | Posidonius | 23 | Eratosthenes | 36 | Grimaldi |
| 11 | Fracastorius | 24 | Copernicus | 37 | Aristarchus |
| 12 | Theophilus | 25 | Ptolemy | ||
| 13 | Piccolomini | 26 | Alphonsus |
| A | Mare Crisum | F | Mare Imbrium | V | Altai Mountains |
| B | Mare Fercunditatis | G | Sinus Iridum | W | Mare Vaporum |
| C | Mare Nectaris | H | Oceanus Procellarum | X | Apennine Mountains |
| D | Mare Tranquilitatis | I | Mare Humorum | Y | Caucasus Mountains |
| E | Mare Serenitatis | K | Mare Nubium | Z | Alps |
The constantly growing progress of optics leads to perpetual new discoveries in science, and at the present time we can say that we know the geography of the Moon as well as, and even better than, that of our own planet. The heights of all the mountains of the Moon are measured to within a few feet. (One cannot say as much for the mountains of the Earth.) The highest are over 7,000 meters (nearly 25,000 feet). Relatively to its proportions, the satellite is much more mountainous than the planet, and the plutonian giants are much more numerous there than here. If we have peaks, like the Gaorisankar, the highest of the Himalayas and of the whole Earth, whose elevation of 8,840 meters (29,000 feet) is equivalent to 1⁄1,140 the diameter of our globe, there are peaks on the Moon of 7,700 meters (25,264 feet), e.g., those of Doerfel and Leibniz, the height of which is equivalent to 1⁄470 the lunar diameter.
Tycho's Mountain is one of the finest upon our satellite. It is visible with the naked eye (and perfectly with opera-glasses) as a white point shining like a kind of star upon the lower portion of the disk. At the time of full moon it is dazzling, and projects long rays from afar upon the lunar globe. So, too, Mount Copernicus, whose brilliant whiteness sparkles in space. But the strangest thing about these lunar mountains is that they are all hollow, and can be measured as well in depth as in height. A type of mountain as strange to us as are the seas without water! In effect, these mountains of the moon are ancient volcanic craters, with no summits, nor covers.
At the top of the highest peaks, there is a large circular depression, prolonged into the heart of the mountain, sometimes far below the level of the surrounding plains, and as these craters often measure several hundred kilometers, one is obliged, if one does not want to go all round them in crossing the mountain, to descend almost perpendicularly into the depths and cross there, to reascend the opposite side, and return to the plain. These alpine excursions incontestably deserve the name of perilous ascents!
No country on the Earth can give us any notion of the state of the lunar soil: never was ground so tormented; never globe so profoundly shattered to its very bowels. The mountains are accumulations of enormous rocks tumbled one upon the other, and round the awful labyrinth of craters one sees nothing but dismantled ramparts, or columns of pointed rocks like cathedral spires issuing from the chaos.
As we said, there is no atmosphere, or at least so little at the bottom of the valleys that it is imperceptible. No clouds, no fog, no rain nor snow. The sky is an eternally black space, vaultless, jeweled with stars by day as by night.
Let us suppose that we arrive among these savage steppes at daybreak: the lunar day is fifteen times longer than our own, because the Sun takes a month to illuminate the entire circuit of the Moon; there are no less than 354 hours from the rising to the setting of the Sun. If we arrive before the sunrise, there is no aurora to herald it, for in the absence of atmosphere there can be no sort of twilight. Of a sudden on the dark horizon come flashes of the solar light, striking the summits of the mountains, while the plains and valleys are still in darkness. The light spreads slowly, for while on the Earth in central latitudes the Sun takes only two minutes and a quarter to rise, on the Moon it takes nearly an hour, and in consequence the light it sends out is very weak for some minutes, and increases excessively slowly. It is a kind of aurora, but lasts a very short time, for when at the end of half an hour, the solar disk has half risen, the light appears as intense to the eye as when it is entirely above the horizon; the radiant orb is seen with its protuberances and its burning atmosphere. It rises slowly, like a luminous god, in the depths of the black sky, a profound and formless sky in which the stars shine all day, since they are not hidden by any atmospheric veil such as conceals them from us during the daylight.