rages, and many vast waves are lifted up, yet all may appear plain enough to one that stands at the shore. So where there are so many hills, the inequality will be less remarkable if it be discerned at a distance. 2. Though there be mountains in that part which appears unto us to be the limb of the moon, as well as in any other place, yet the bright vapours hide their appearance; for there is an orb of thick vaporous air that doth immediately compass the body of the moon; which though it have not so great opacity, as to terminate the sight, yet being once enlightened by the sun, it doth represent the body of the moon under a greater form, and hinders our sight from a distinct view of her true circumference. of this in the next chapter. But 3. Keplar hath observed*, that in the solary eclipses, when the rays may pass through this vaporous air, there are some gibbosities to be discerned in the limb of the moon. I have now sufficiently proved, that there are hills in the moon; and hence it may seem likely that there is also a world for since providence hath some special end in all its works, certainly then these mountains were not produced in vain; and what more probable meaning can we conceive there should be, than to make that place convenient for habitation. *Somn. Astr. not. 207. PROP. X. That there is an Atmo-sphæra, or an orb of gross, vaporous air immediately encompassing the body of the Moon. As S that part of our air which is nearest to the earth is of a thicker substance than the other, by reason it is always mixed with some vapours which are continually exhaled into it: so is it equally requisite, that if there be a world in the moon, that the air about that should be alike qualified with ours. Now that there is such an orb of gross air, was first of all (for ought I can read) observed by Meslin*, afterwards assented unto by Keplar and Galilæus, and since by Baptista Cittacus, Scheiner, with others, all of them confirming it by the same arguments; which I shall only cite, and then leave this proposition. 1. It is not improbable that there should be a sphere of grosser air about the moon; because it is observed that there are such kind of evaporations which proceed from the sun itself. For there are discovered divers moveable spots, like clouds, that do encompass his body; which those authors who have been most frequently versed in these kind of experiments and studies, do conclude to be nothing else but evaporations from it. The probability and truth of which observations may also be inferred from some other appearances. As, 1. It hath been observed that the sun hath sometimes for the space of four days together †, appeared as dull and ruddy almost as the moon in her eclipses, insomuch that the stars have been seen at mid-day. Nay, he hath been constantly darkened for almost a whole year, and never shined but with a kind of heavy and duskish light, so that * Vide Euseb. Nicrem. de Nat. Hist. 1. 2. c. 11. there was scarce heat enough to ripen the fruits. As it was about the time when Cæsar was killed. Which was recorded by some of the poets. Thus Virgil speaking of the sun. Ille etiam extincto miseratus Cæsare Romam, He pitying Rome when as great Cæsar dy'd, Ovid likewise, speaking of his death, Solis quoque tristis imago Lurida sollicitis præbebat lumina terris. † The sun's sad image then Did yield a lowering light to fearful men. Now these appearances could not arise from any lower vapour: for then, 1. They would not have been so universal as they were, being seen through all Europe: or else, 2. That vapour must have covered the stars as well as the sun, which yet notwithstanding were then plainly discerned in the day-time. You may see this argument illustrated in another the like case, chap. 12. Hence then it will follow, that this fuliginous matter, which did thus obscure the sun, must needs be very near his body; and if so, then what can we more probably guess it to be than evaporations from it? 2. It is observed, that in the sun's total eclipses, when there is no part of his body discernible, yet there does not always follow so great a darkness as might be expected from his total absence. Now it is probable that the reason is, because these thicker vapours being enlightened by his beams, do convey some light unto us, notwithstanding the interposition of the moon betwixt his body and our earth. * Virgil, Georg. 1. 1. + Metam. lib. 15. 3. This likewise is by some guessed to be the reason of the crepusculum, or that light which we have before the sun's rising. Now if there be such evaporations from the sun, much more then from the moon, which does consist of a more gross and impure substance. The other arguments are taken from several observations in the moon herself, and do more directly tend to the proof of this proposition. 2. It is observed, that so much of the moon as is enlightened, is always part of a bigger circle than that which is darker. The frequent experience of others hath proved this, and an easy observation may quickly confirm it. But now this cannot proceed from any other cause so probable as from this orb of air; especially when we consider how that planet shining with a borrowed light, doth not send forth any such rays as may make her appearance bigger than her body. 3. When the moon being half enlightened, begins to cover any star, if the star be towards the obscurer part, then may it by the perspective be discerned to be nearer unto the center of the moon than the outward circumference of the enlightened part. But the moon being in the full, then does it seem to receive these stars without its limb. 4. Though the moon do sometime appear the first day of her change, when so much as appears enlightened cannot be above the 80th part of her diameter, yet then will the horns seem at least to be of a finger's breadth in extension; which could not be, unless the air about it were illuminated. 5. It is observed in the solary eclipses, that there is sometimes a great trepidation about the body of the moon, from which we may likewise argue an atmosphæra, since we cannot well conceive what so probable a cause there should be of such an appearance as this, Quod radii solares a vaporibus lunam ambientibus fuerint intercisi*, that the sun-beams were broken and refracted by the vapours that encompassed the moon. 6. I may add the like argument taken from another observation which will be easily tried and granted. When the sun is eclipsed, we discern the moon as she is in her own natural bigness; but then she appears somewhat less than when she is in the full, though she be in the same place of her supposed excentrick and epicycle; and therefore Tycho hath calculated a table for the diameter of the divers new moons. But now there is no reason so probable to solve this appearance, as to place an orb of thicker air near the body of that planet, which may be enlightened by the reflected beams, and through which the direct rays may easily penetrate. But some may object, that this will not consist with that which was before delivered, where I said, that the thinnest parts had least light. If this were true, how comes it to pass then that this ait should be as light as any of the other parts, when as it is the thinnest of all? I answer, if the light be received by reflection only, then the thickest body hath most, because it is best able to beat back the rays; but if the light be received by illumination (especially if there be an opacous body behind, which may double the beams by reflexion) as it is here, then I deny not but a thin body may retain much light; and perhaps some of those appearances which we take for fiery comets, are nothing else but a bright cloud enlightened; so that probable it is there may be such air without the moon: and hence it comes to pass, that the greater spots are only visible towards her middle parts, and none near the circumference; not but that there are some as well in those parts as elsewhere, but they are not there perceiveable, by reason of those brighter vapours which hide them. |