CHAPTER VII.

OF THE MOON.

Is it possible, that my dear child can behold yon beauteous orb, without feeling an irresistible desire, to know something more respecting its character and influence? Let your tender mind kindle into devotion at such a season as the present, when this delicately beautiful planet is riding in awful majesty on high, attended by a multitude of lesser lights, which appear to follow in her train, or to decorate her path.

You know, mamma, how I love to hear you talk; attention does not tire me, difficulties do not discourage. I will, therefore, by immediately proposing a question to you, evince my anxiety to know more. While we are now looking at the moon, I observe a number of spots; what am I to understand they are?

Unassisted by the telescope, we naturally suppose, they are seas, and continents, mountains, and valleys; but on a more accurate inspection with the telescope we discern immense elevations and depressions, resembling the valleys, and mountains, on our earth.

And do you think, that they do not merely

resemble them, but that they really are valleys and mountains?

From the appearance of the shadows cast by these spots it is obvious, they are mountains; for in all situations of the moon, the elevated parts cast a triangular shadow in a direction opposite to the sun, while the cavities are always dark on the side next the sun, and illuminated on the opposite one, which is exactly conformable to what we observe of hills, and valleys, on the earth.

Are there any means of determining the height of these elevations?

As the tops of the mountains are considerably elevated above the other parts of the moon's surface, they are frequently illuminated, when they are at a considerable distance from the confines of the enlightened hemisphere; and the result of this circumstance is, that astronomers are enabled to determine their altitude.

And what height are they found?

P. Riccioli observed, that the hill called St. Catherine, was about one sixteenth part of the moon's diameter, and according to his calculation, its height was nearly nine miles, which is much higher than any mountain on the earth.

But you have spoken to me once, or twice, so highly of Sir William Herschel, that I should like to know, what he says of the height of the lunar mountains.

They have, he thinks, been over-rated, and that with a few exceptions the greater part do not exceed half a mile in perpendicular elevation.

Have not volcanoes been discovered in the moon?

Yes; Herschel discovered three, in the dark part of the moon, of which two appeared nearly extinct, whilst the third exhibited an actual eruption of fire, or luminous matter. It appeared to burn with great violence, and might be computed to be about three miles in diameter. The eruption resembled a piece of burning charcoal, covered by a thin coat of white ashes. All the adjacent parts of the volcanic mountain were faintly illuminated by the eruption, and, in proportion to their distance from the crater, became more obscure.

You mentioned the name of St. Catherine, as appropriated to a spot on the moon; is, then, each place of consequence, distinguished by a proper name?

Yes: Riccioli divided the lunar regions among those philosophers and astronomers who have distinguished themselves by advancing the knowledge of the heavens; giving the names of the most celebrated characters, to the largest spots, and those of less eminence to the smallest; and this method is generally followed.

Will you tell me the names, mamma?

3