M. Quêtelet, a living and highly respectable authority, and a man of science peculiarly devoted to the study of subjects of exactitude. "Our vast continents, our seas, even our forests," says M. Quêtelet, (Astronomie Elémentaire, Paris, 1826,)" are visible to them: they perceive the enormous piles of ice collected at the Poles, and the girdle of vegetation which extends on both sides of the Equator; as well as the clouds which float over our heads, and sometimes hide us from them. The burning of a forest or town could not escape them; and, if they had good optical instruments, they could even see the building of a new town, or the sailing of a fleet!" But some, at least, of these things will appear the less incredible to you, the more you know about the real intimate relations between What does M. Quêtelet think of the sights which might be seen upon the earth from the moon, supposing that there were in the moon people like ourselves, and telescopes like ours? D the earth and moon; and the reported facts which follow, will perhaps assist you in that respect. It frequently happens, about three or four days after the new moon, that within the crescent appears the rest of the figure of the moon. I have represented this appearance in the beautiful figure which forms my Frontispiece; and which I repeat here, considering it, at present, only as showing the ash-coloured light which covers so large a part of the disc, and which is that of which I am now speaking. This phenomenon is what the French call la lumière cendrée; that is, "the ash-coloured light;" and it arises from the reflection of the light (that is, of the sunshine) from the earth upon the moon, which thus illuminates, to a certain degree, that face of the moon which is presented to the earth. The thin crescent, at such a time, reflects to us the full blaze of the solar light; and the rest of the surface of the moon reflects to us the light reflected upon it from a body thirteen times larger than the moon, while moonlight comes to the earth from a body thirteen times less! It is observed that this lumière cendrée is brighter upon the moon when the continents of the earth are opposite, than when either the Atlantic or Pacific Ocean is in that position. The sea reflects less light upon the moon than the dry land; and consequently the latter, in those circumstances, reflects less of the lumière cendrée upon the earth. But here, again, you will understand, why the spots, or dark parts of the moon, have sometimes been called its seas and lakes-its brighter parts being taken for dry land. According to others, however, the moon has no water whatever; and its spots are dry vales, and cavities and basins, and shadows of mountains; but all Do the French astronomers, after the ancients, apply to a certain appearance of the moon the name of la lumière cendrée, or "ash-coloured light:" in Latin, lumèn incinerosum? without the refreshment of a single drop of water. I have questioned this already, and cited at least one astronomer to the contrary. The moon, too, it is equally said, is without an atmosphere, that is, without air, (though Sir David Brewster, as we have seen, lifts his lunar mountains into lunar "air,") and without clouds or vapour. But none of these things are finally agreed upon, even by our living astronomers; and, if we consult their various writings, we shall find that there is still room for inquiring whether the moon has air, that is, an atmosphere; whether the moon has water; and even whether its light is really but a light borrowed from the sun; that is, a reflection of the light of the sun; and not a light of its own, drawn forth by the action of the mass of the sun? As to clouds, which are vapour, and which directly imply the presence of water, I have told you that M. Gruïthuisen believes himself to have discovered them on the mountains in the moon. |