"And now, looking a little to the left of Copernicus, you will see that grand range of mountains, the Lunar Apennines (Fig. 7), which stretches 400 miles across the face of the moon. Other mountain ranges we could find, but none so like mountains on our own globe as these, with their gentle sunny slope down to a plain on the left, and steep perpendicular cliffs on the right. The highest peak in this range, called Huyghens, rises to the height of 21,000 feet, higher than Chimborazo in the Andes. Other mountains on the moon, such as those called the Caucasus, south of the Apennines, are composed of disconnected peaks, while others again stand as solitary pyramids upon the plains."
Fig. 7.
The Lunar Apennines.
(Copied by kind permission of MM. Henri from part of a magnificent photograph taken by them, March 29, 1890, at the Paris Observatory.)
"But we must hasten on, for I want you to observe those huge walled crater-plains which have no hill in the middle, but smooth steel-grey centres shining like mirrors in the moonlight. One of these, called Archimedes, you will find just below the Lunar Apennines (Figs. 3 and 7), and another called Plato, which is sixty miles broad, is still lower down the moon's face (Figs. 3 and 8). The centres of these broad circles are curiously smooth and shining like quicksilver, with minute dots here and there which are miniature craters, while the walls are rugged and crowned with turret-shaped peaks."
Fig. 8.
The crater Plato as seen soon after sunrise. (After Neison.)
"It is easy to picture to oneself how these may once have been vast seas of lava, not surging as in Copernicus, and heaving up as it cooled into one great central cone, but seething as molten lead does in a crucible, little bubbles bursting here and there into minute craters; and this is the explanation given of them by astronomers.
"And now that you have seen the curious rugged face of the moon and its craters and mountains, you will want to know how all this has come about. We can only form theories on the point, except that everything shows that heat and volcanoes have in some way done the work, though no one has ever yet clearly proved that volcanic eruptions have taken place in our time. We must look back to ages long gone by for those mighty volcanic eruptions which hurled out stones and ashes from the great crater of Tycho, and formed the vast seas of lava in Copernicus and Plato.