[58] We are not assured that this alteration has taken place in the part of the moon that has some resemblance to a woman's head: but there must be changes, if we judge by the volcano which has been repeatedly observed. Astron. Art. 3339.
What are you talking of? cried the Marchioness. I am not jesting, I replied. A figure has been observed in the moon which resembled a woman's head rising from among the rocks, and in that part an alteration is perceived. Some pieces have fallen off a mountain, and left the points which appear like the forehead, nose and chin of an old woman. Does it not seem, said she, as if some malignant power had a spite against beauty, since the young lady's head is the only spot in the moon that has undergone a change. Perhaps, answered I, to make amends, the alterations on our globe may give additional beauty to some face observed by the inhabitants of the moon, I mean some face formed like those of the people in that planet, for we always try to discover in distant objects, the resemblance of what we continually think of. Our astronomers discern young ladies' faces in the moon; probably if women were to examine it they would find handsome male faces. If I to look, I don't know whether I should not see your likeness, madam. I must undoubtedly, said she, feel myself obliged to any body who could find me there; but let us return to what we were talking of just now; are there any considerable alterations on the earth? In all probability there are, answered I. Many high mountains, at a great distance from the sea, have on them beds of shells, which shew that they were formerly covered with water. Sometimes likewise, at a distance from the sea, are found stones containing petrified fishes. How could they have got to that place unless the water had been there? Fables tell us, that Hercules separated with his hands two mountains called Calpe and Abila, which being situated between Africa and Spain obstructed the ocean; and the sea immediately rushed in violently, and formed the great gulph that we call the Mediterranean. Fables are not altogether fabulous; they are histories of remote periods, disguised by two very ancient and common defects; ignorance, and a love of the marvellous. It is not very credible that Hercules separated the two mountains with his hands; but I can easily believe that in the time of some Hercules, (for there have been fifty), the ocean may have torn asunder, perhaps with the assistance of an earthquake, two mountains more feeble than the rest and have by that means rushed in between Europe and Africa. Then a new spot was discovered on our globe, by the people in the moon, for you recollect, madam, that the water forms a dark spot. It is the general opinion that Sicily has been separated from Italy, and Cyprus from Syria: new islands have sometimes been formed in the sea; earthquakes have ingulfed some mountains, and produced others, as well as changed the course of rivers. Philosophers give us reason to fear that the kingdom of Naples and Sicily, being over great subterranean vaults filled with sulphur, will some time or other fall in, when the vaults are no longer strong enough to resist the fires contained in them, which now have vent at such openings as Vesuvius and Ætna. All this will be sufficient to diversify a little the appearance we make to the inhabitants of the moon.
I would rather tire them said the Marchioness, with a monotonous appearance, than entertain them by the ruin of provinces.
That is nothing, answered I, to what takes place in Jupiter. He appears to be surrounded with belts, which are distinguished from each other, or from the spaces betwixt them, by their different degrees of light. These are land and seas—or at least parts of the planet differing in their nature. Sometimes these lands grow narrower, sometimes wider. New ones are formed in various parts, and some of the old ones disappear: and all these changes visible only through our best telescopes, are in themselves much more considerable than if our ocean were to inundate all the land, and leave its own bed to form new continents. Unless the inhabitants of Jupiter are amphibious, and live with equal ease either on land or in water, I hardly know what can become of them.[59] We see likewise great alterations on the surface of Mars, even from one month to another. In that short time seas overflow large continents, and retire by a flux and reflux a thousand times more violent than ours; or if this be not the case, some change equivalent to it takes place. Our planet is very quiet compared with these; we have great reason to congratulate ourselves, especially if it is true that in Jupiter countries as extensive as Europe have been set on fire. Set on fire! cried the Marchioness; that would be a great piece of news there. It would indeed, answered I. We have observed in Jupiter, for perhaps twenty years, a long stream of light more brilliant than the rest of the planet.[60] We have had deluges here, but very seldom; perhaps in Jupiter they have now and then a large conflagration as well as frequent deluges. But be that as it may, the brilliant light I spoke of is very different from another, which apparently is as old as the world, though it has but lately been discovered.[61] How can a light be formed for concealment? said she, that is something quite out of the common way.
[59] These lands surrounding Jupiter, which are sometimes few, and sometimes in great numbers, are apparently clouds.
[60] I don't know that this observation is authentic.
[61] The zodiacal light. Astron. Art. 844.
This light, I replied, is only visible at twilight, which is most frequently long enough, and of sufficient power to conceal it; and when it is not hid by the twilight, either the vapours of the horizon prevent us from seeing it, or without great attention we may even mistake it for twilight. However, about thirty years since it was discovered with certainty, and for some time gave great delight to the astronomers, whose curiosity wanted stimulating by something new. They might find as many new subaltern planets as they chose without feeling any interest in them. The two last moons of Saturn, for instance, did not enrapture them as Jupiter's satellites had done; custom destroys the power of every thing.
We see, during a month before and after the equinox of March, when the sun is set and the twilight disappeared, a sort of whitish light resembling the tail of a comet. It is seen before the dawn and sun-rise, towards the equinox of September, and morning and night towards the winter solstice. At other times, as I have before said, the twilight conceals it; for we have reason to believe it always exists. It has lately been conjectured that it is produced by a large mass of matter, somewhat dense, which environs the sun for a certain extent. The greatest part of his rays penetrate this covering, and come to us in a straight line; but some of these rays by striking against the internal surface are reflected back to us, either before the direct rays can reach us in the morning, or after they have ceased to enlighten us in the evening. As these reflected rays come from a higher region than the direct ones, it is therefore earlier when we receive them, and later before we lose them.
On this ground I must retract what I said on the probability of the moon having no twilight, for want of a surrounding atmosphere as dense as that of the earth. She is no loser by it, if she can receive a twilight through this thick air which surrounds the sun, and reflects his light to places which could not have his direct rays. Then, enquired the Marchioness, will not this be a source of twilight to all the planets, without the necessity of a dense atmosphere to environ each, since that which surrounds the sun may produce the same effect for all the planets in the vortex? From the frugality of nature, I am disposed to believe she has effected the purpose by this means only. Yet, said I, in spite of this frugality, the earth would have two causes of twilight, one of which (the dense air before the sun), would be useless, and could only serve as an object of curiosity to the frequenters of the observatory: but it may be that the earth alone sends out exhalations sufficiently gross to produce twilight; and therefore a general resource has been provided for the other planets, if their evaporations are more pure and subtile. We, perhaps, of the inhabitants of all the worlds in our vortex breathe the grossest air; did the people of the other planets know that, with what contempt they would survey us!