13. Sea of Showers

14. Aristarchus

15. Herodotus

16. Ocean of Storms

17. Copernicus

18. Apennine Mountains

19. Sea of Serenity

20. Haemus Mountains

21. Sea of Conflicts

22. Proclus

23. Sea of Tranquillity

24. Sea of Fertility

25. Hevel

26. Kepler

27. Grimaldi

28. Flamsteed

29. Bonpland

30. Ga.s.sendi

31. Sea of Vapours

32. Hipparchus

33. Albategnius

34. Ptolemaeus

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 Ptolemaeus. 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 alt.i.tude. 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.

Pa.s.sing 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 alt.i.tude.

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.