1. Are the spots upon the moon occasioned by the peculiarity of its surface? Is that surface diversified into mountains and valleys? Are the mountains said to contain volcanoes? 2. What did the ancient Greek philosophers say of the moon? 3. What is the evening telescopic figure of the crescent, or growing or increasing moon, a little after the new moon?

CHAPTER VI.

PARLEY TELLS OF THE MOUNTAINS IN THE MOON. SIR DAVID BREWSTER'S DESCRIPTION OF THE MOUNTAIN-SCENERY IN THE MOON, AND HIS DISAGREEMENT WITH SIR WILLIAM HERSCHEL AS TO THE HEIGHT OF THE MOUNTAINS.

1. BEFORE the time of Sir William Herschel, some of the mountains in the moon were held to be of the most extraordinary height, in proportion to those of the earth; and you may still meet with statements of that kind in many modern books; but "I believe," says Sir William, "that the height of the lunar mountains is in general overrated, and that when we have excepted a few, the generality do not exceed half a mile in perpendicular elevation."

2. The following description of the mountain-scenery of the moon, by Sir David Brewster (if, considering its poetical tone, it can be wholly trusted), is, in the meantime, sufficiently striking: "The mountain-scenery of the moon bears a stronger resemblance to the lowering sublimity and terrific ruggedness of the Alpine regions (the Swiss Alps) than to the tamer inequalities of less elevated countries. Huge masses of rock rise at once from the plains, and raise their peaked summits to an immense height in the air, while projecting crags spring from their rugged flanks, and, threatening the valleys below, seem to bid defiance to the laws of gravitation. Around the base of these frightful emi

nences are strewed numerous loose and unconnected fragments, which time seems to have detached from the apparent mass; and, when we examine the rents and ravines which accompany the overhanging cliffs, we expect every moment that they are to be torn from their base, and that the process of destructive separation, which we had only contemplated in its effects, is about to be exhibited to us in tremendous reality! The mountains called the Apennines, which traverse the moon's disc from north-east to south-west, rise with a precipitous and craggy front from the level of the Mare Imbrum. In some places, their perpendicular elevation is above four miles; and, though they often descend to a much lower level, they present an inaccessible barrier to the north-east, while, on the south-west, they sink in gentle declivity to the plains."

3. But Sir John Herschel, the son of the late Sir William, carries us still further, as to the description of the mountains in the moon; and, here, let me caution my little readers, that I am now talking of mountains in the moon, which are topics of astronomy; and not of the mountains of the Moon, (so called,) which are certain mountains in Africa, and belong, therefore, to geography.

4. After this account of the mountain-scenery in the moon, which (if you have not heard it before) must, no doubt, have greatly surprised you, it will still appear very wonderful that Sir John Herschel, by the help of improved telescopes, is able to talk of the actual geology

C

of the moon, or of the stratification and composition of those rocks which Sir David Brewster so minutely and terrifically pictures!

5. "The generality of the mountains in the moon present," says Sir John, "a striking uniformity and singularity of aspect. They are wonderfully numerous,

occupying by far the greater part of the surface, and almost universally of an exactly circular or cup-shaped form, foreshortened, however, into ellipses towards the limbs; but the larger have, for the most part, flat bottoms within, from which rises centrically a small, steep, conical hill. They offer, in short, in its highest perfection, the true volcanic character; and, in some of the principal ones, decisive marks of volcanic stratification, arising from successive deposits of ejected matter, may be clearly traced with powerful telescopes."

6. The appearance of these "cup-shaped" summits, or craters, will be remarked as conspicuous in my figures. The "foreshortening," mentioned above, belongs to the perspective of the circles, which are turned away from the eye, upon the retiring sides of the globe or ball of the moon.

7. The figure upon the next page, besides showing you some of these craters of the volcanoes in the moon, shows you also the moon in its decrease, or third quarter; or when only its eastern half is enlightened.

QUESTIONS.

1. What has been said about the height of the mountains in the moon? 2. What description has been given of the mountainscenery in the moon? Does Sir David Brewster seem to support, at least partially, the older opinion, as to the great height of the mountains in the moon? 5. How does Sir John Herschel describe rocks, bountains, and volcanoes in the moon? 6. How does Sir John Herschel's account of the numerous craters in the moon agree with the circular figures upon Parley's three maps? What are the craters of volcanoes? 7. What is the telescopic figure of the moon in its decrease?