I, however, again reminded them that, although these areas are termed seas and oceans, no water exists there now, whatever may have been the case in the long distant past. They are now only large depressions, and not often level but intersected by hills, ridges, and even mountains.
As we passed along I called their particular attention to the magnificent "Bay of Rainbows" on the north-eastern coast of the Sea of Showers. "From Cape Laplace (9000 feet high) on the western extremity, to Cape Heraclides (4000 feet high) on the eastern extremity, this great bay is about 140 miles across, the depth of its curvature being over eighty miles. It bears a very strong resemblance to many large bays on our sea-coasts in various parts of the world, but I am not aware of any such bay which is bordered by a mass of such lofty mountains as this is.
"We are looking at it now under a high sun, but when the sun has only just risen sufficiently high to illuminate all those high mountains, whilst the lower surroundings are still in shadow, the great bay presents in the telescope the appearance of a brilliant luminous arch springing from the lighted part of the moon and extending far out over the dark part of the disc.
"Farther eastward, and lower down on the Ocean of Storms, you will observe what is admitted by all to be the very brightest large formation upon the moon, viz. Aristarchus—a ring-plain nearly thirty miles in diameter, the floor of which is 5000 feet below the surface level. It possesses a central mountain, very difficult to measure on account of the general brightness, but believed to be about 1300 feet high. Well-defined terraces are seen on the mountain walls enclosing the area, and many external ridges are connected with the walls, especially to the south. This formation is evidently covered with some substance which reflects light to a greater extent than that on similar formations; indeed it appears so bright that when the moon is new and the whole of this part of the disc is dark, Aristarchus can still be seen with a telescope, and this gave rise in the past to the idea that it was a volcano in actual eruption. The explanation is, however, more prosaic, because the mountain is really brought into view by earthshine on its bright covering. When the moon is new the earth is almost fully lighted on the side toward the moon, and sheds a faint light on the dark portion of its disc, thus producing the phenomenon known as 'the old moon in the new moon's arms.'
"Close to Aristarchus you will notice another ring-plain, which is called Herodotus, about twenty-three miles in diameter, with a floor 7000 feet depressed; but this formation is not nearly so bright as its neighbour. That high plateau between them is notable on account of the T-shaped cleft in it, which runs into that other long zig-zag cleft (in some parts two miles wide and 1600 feet in depth), whose direction changes abruptly several times in its length of over one hundred miles.
"Turning from this towards the south-west you will see the most majestic formation to be found upon the moon—the great ring-plain called 'Copernicus,' after the founder of our present system of astronomy. It is about sixty miles in diameter, only roughly circular in shape, and as it stands isolated upon the great ocean-bed it is most favourably situated for observation. A large number of very high ridges, separated by deep valleys, radiate from it in all directions to a distance of hundreds of miles, presenting the appearance of a grand system of buttresses to the mountain walls. These walls are high, and contain a very large number of peaks which, when seen through the telescope as they catch the sunlight, look like a string of bright pearls shining on the border of the ring. A peak on one side is 12,000 feet in altitude, on the other side is one only 1000 feet lower, whilst, rising from near the central part of the floor, are no less than five small mountain peaks. Owing to its size, brightness, and isolated position, this splendid ring-mountain can be seen from the earth without the aid of a glass; but even a field-glass will reveal much in this and similar formations which cannot be detected by the unaided eye.
"The Rev. T.W. Webb has termed Tycho, in the southern hemisphere, 'the Metropolitan Crater of the Moon,' but, in my opinion, Copernicus is, owing to its position and grandeur, much more worthy of that dignity. Tycho is fine in itself, but is not so favourably situated, being surrounded by other formations somewhat in the same way as St. Paul's Cathedral is surrounded and shut in, for the most part, by other and meaner buildings.
"How much more should we appreciate the splendid proportions and majesty of our Metropolitan Cathedral if we could view it as an isolated building with a fine open space all around it!"
"I quite agree with that, Professor," remarked John, "and I have always thought it a great pity that Sir Christopher Wren was not allowed to carry out his original plan in this respect."
We were looking at the Carpathian range of mountains just to the northward of Copernicus, when M'Allister touched my arm, exclaiming, "Look, Professor, at all those tiny craters near the western side of Copernicus. Why, there are so many of them that the ground for miles round looks like a honeycomb, and in some places there are straight rows of them!"