22. Proclus
23. Sea of Tranquillity
24. Sea of Fertility
25. Hevel
26. Kepler
27. Grimaldi
28. Flamsteed
29. Bonpland
30. Gassendi
31. Sea of Vapours
32. Hipparchus
33. Albategnius
34. Ptolem?us
35. Alphonsus
36. Arzachel
37. Theophilus
38. Cyrillus
39. Catherina
40. Sea of Nectar
41. Langrenus
42. Vendelinus
43. Petavius
44. Schickard
45. Wargentin
46. Tycho
47. Maurolycus
48. Clavius
49. Newton
50. Straight Wall
51. Sea of Moisture
52. Sea of Clouds]
Proceeding on our tour of inspection, we crossed the Ocean of Storms to a point near the central part of the lunar surface, and I showed them the fine walled plain called Ptolem?us. This is 115 miles in diameter, and contains an area as large as the combined areas of Yorkshire, Lancashire, and Westmorland, its highest peak being 9000 feet in altitude. It forms the most northerly of a line of walled plains, the most southerly being Arzachel, which is sixty-six miles in diameter, and has a very depressed floor; while one peak on the walls rises to a height of 13,000 feet.
Passing farther west, we next examined another splendid group of three ring-mountains, arranged in a line running nearly north and south, viz. Theophilus, Cyrillus, and Catherina. The first is the most northerly, and is about sixty-four miles in diameter, with several very high peaks—one rising as much as 18,000 feet, and two on the opposite side being 16,000 and 14,000 feet high respectively. Even the central mountain is very large in area, and 6000 feet high. “That,” I remarked to M’Allister, “is nearly half as high again as Ben Nevis, the highest mountain in Scotland, which is, after all, only 4400 feet high.”
“Ben Nevis, Professor, is 4406 feet high!” corrected M’Allister.
“That’s right, M’Allister,” said John, clapping him on the back, “stick up for bonnie Scotland, and don’t let her be robbed of that six feet of mountain!”
Proceeding, I then said that Cyrillus, the middle ring, was, as they could see, very irregular in shape; and the walls were in some parts very much broken and damaged.
Catherina is the largest of the three, being over seventy miles in diameter, and its highest peak is 16,500 feet in altitude.
I should have liked to have shown them the splendid double-walled plain called Petavius, which has a convex floor some 800 feet higher in the centre than at the edges. We were, however, too late both for that and Langrenus, another fine formation on the same meridian, for the sun had set upon them and they were in darkness, so it was no use going any farther in that direction.
We now directed our course over the Sea of Clouds till we arrived at what is known as the “Straight Wall.”
“M’Allister,” I said, “that ought to interest you, for there is a somewhat similar formation in Scotland. You see this is an escarpment, or cliff, over sixty miles long, and varying from about 600 feet to 900 feet in height.
“This cliff is one of the best known examples on the moon of what in geology is termed a ‘fault,’ indicating either that one part of the general surface has been greatly elevated, or that the adjoining part has been depressed. We have many examples of such ‘faults’ on the earth—for instance, one runs a long way across Scotland, from Stonehaven round to Helensburgh, between the Highlands and the Lowlands, and is about 120 miles in length. That is about twice the length of the Straight Wall; so you see that Scotland can beat the moon in that respect!”
This brought M’Allister up to the scratch. “Scotland,” he exclaimed excitedly, “can hold her own in most things! Why, mon, the empire is indebted to her for the finest statesmen, the cleverest lawyers, the best engineers and scientists, and, allow me to say, the bravest soldiers in the whole world! Scotsmen go everywhere, and can do anything!”
“Oh yes, M’Allister,” said John, with a laugh, “and a Scotsman has got to the moon! but, please, do not forget that two Englishmen planned the trip, and devised the means of accomplishing the journey!”
M’Allister smiled a rather wintry smile, and then subsided. John was a bit too smart for him that time.
Passing on, we inspected the large cleft running parallel to the Straight Wall, and the small mountain close by named after Birt, the well-known selenographer. We then crossed the Sea of Clouds again, and had a long look at the great system of straight clefts near Campanus and Hippalus, together with the fine walled plain Gassendi, the floor of which is at some parts 2000 feet above the lunar surface. I had often studied this through the telescope, as it is a most interesting formation.
“Well, Professor,” remarked M’Allister, “I have travelled nearly all over our own world, but in all my journeyings I have never seen such wild and rugged scenery as I have during the few hours we have been passing over the moon. The mountains seem to be split and rent in all directions, especially where there are volcanic craters in the neighbourhood—and, really, they seem to be everywhere; while landslips are very numerous, and the mountain passes are extremely rugged and gloomy.”
“Yes,” I replied, “my telescopic observations had prepared me for a great deal, but the weird ruggedness of the lunar scenery exceeds all my anticipations.”
“What is the explanation of it all?” M’Allister inquired.
“I should think, M’Allister, that much of it was originally caused by the extreme violence of volcanic outbursts,” I answered; “but the excessive expansion and contraction, resulting from the alternate spells of intense heat and intense cold to which the moon is continually exposed, will account for the formation of many of those tremendous chasms and precipices which we see everywhere around us, as well as for the huge mounds of dislodged rocks and debris, which are piled up in such chaotic confusion on the ledges of the mountains and round their bases.
“On the earth such debris would very soon have become smoothed by atmospheric erosion, the interstices would have been filled up with dust and soil, while the growth of vegetation would have added a new charm to the effect.
“You have seen the great landslip in the Isle of Wight! When it fell all was wild desolation, but it has become covered with such a luxuriant growth of vegetation that it now presents a scene of beauty.
“On the moon, however, there is neither atmosphere, rain, nor moisture to produce weathering of the rocks or to encourage the growth of vegetation; so the rocks remain just as sharp, rugged, and bare as they were ages ago when they were first split off from the mountains.
“No doubt very large masses of rocks are still frequently being dislodged, and if we could see them falling from the upper part of a mountain, rebounding along the spurs, with fragments flying in all directions and ultimately
