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proportion of two to seven. Suppose withal that the earth's diameter contains about 7000 Italian miles, and the moon's 2000 (as is commonly granted.) Now Galilæus hath observed, that some parts have been enlightened, when they were the twentieth part of the diameter distant from the common term of illumination. From whence it must necessarily follow, that there may be some mountains in the moon so high, that they are able to cast a shadow a hundred miles off. An opinion that sounds like a prodigy or a fiction; wherefore it is likely that either those appearances are caused by somewhat else besides mountains, or else those are fallible observations; from whence may follow such improbable, inconceivable consequences. But to this I answer;

1. You must consider the height of the mountains is but very little, if you compare them to the length of their shadows. Sir Walter Rawleigh* observes that the mount Athos, now called Lacas, casts its shadow 300 furlongs, which is above 37 miles; and yet that mount is none of the highest. Nay Solinus + (whom I should rather believe in this kind) affirms that this mountain gives his shadow quite over the sea, from Macedon to the isle of Lemnos, which is 700 furlongs, or 84 miles, and yet according to the common reckoning it doth scarce reach 4 miles upwards in its perpendicular height.

2. I affirm that there are very high mountains in the moon. Keplar and Galilæus think that they are higher than any which are upon our earth. But I am not of their opinion in this, because I suppose they go upon a false ground, whilst they conceive that the highest mountain upon the earth is not above a mile perpendicular.

Whereas it is the common opinion, and found true enough by observation, that Olympus, Atlas, Taurus and Emus, with many others, are much above this height. Tenariffa, in the Canary islands, is commonly related to be above 8 miles perpendicular, and about this height (say Poly. Hist. c. 21.

*Hist. 1. 1. cap. 7. sect. 11.

some) is the mount Perjacaca in America. Sir Walter Rawleigh* seems to think that the highest of these is near 30 miles upright: nay Aristotle, speaking of Caucasus in Asia, affirms it to be visible for 560 miles, as some interpreters find by computation; from which it will follow, that it was 78 miles perpendicularly high; as you may see confirmed by Jacobus Mazonius †, and out of him in Blancanus the Jesuit. But this deviates from the truth more in excess than the other doth in defect. However, though these in the moon are not so high as some amongst us; yet certain it is they are of a great height, and some of them at the least four miles perpendicular. This I shall prove from the observation of Galilæus, whose glass can shew to the senses a proof beyond exception; and certainly that man must needs be of a most timorous faith, who dares not believe his own eye.

By that perspective you may plainly discern some enlightened parts (which are the mountains) to be distant from the other about the twentieth part of the diameter. From whence it will follow, that those mountains must necessarily be at the least four Italian miles in height.

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*Hist. 1. 1. c. 7. sect. 11. Meteor. 1. 1. c. 11.

+ Comparatio Arist. cum. Platone, sect. 3. c. 5, Expost in loc. Matth. Arlis loc. 148.

For let B D E F be the body of the moon, A B C will be a ray or beam of the sun, which enlightens a mountain at A, and B is the point of contingency; the distance betwixt A and B must be supposed to be the twentieth part of the diameter, which is an 100 miles, for so far are some enlightened parts severed from the common term of illumination. Now the aggregate of the quadrate from A Ba hundred, and B G 1000 will be 1010000; unto which the quadrate arising from A G must be equal; according to the 47th proposition in the first book of elements. Therefore the whole line A G is somewhat more than 104, and the distance betwixt H A must be above 4 miles, which was the thing to be proved.

But it may be again objected, if there be such rugged parts, and so high mountains, why then cannot we discern them at this distance? Why doth the moon appear unto us so exactly round, and not rather as a wheel with teeth?

I answer, by reason of too great a distance; for if the whole body appears to our eye so little, then those parts which bear so small a proportion to the whole, will not at all be sensible.

But it may be replied, if there were any such remarkable hills, why does not the limb of the moon appear like a wheel with teeth, to those who look upon it through the great perspective, on whose witness you so much depend? Or what reason is there that she appears as exactly round through it, as she doth to the bare eye? certainly then either there is no such thing as you imagine, or else the glass fails much in this discovery.

To this I shall answer out of Galilæus.

1. You must know, that there is not merely one rank of mountains above the edge of the moon, but divers orders, one mountain behind another, and so there is somewhat to hinder those void spaces which otherwise, perhaps, might appear,

Now where there be many hills, the ground seems even to a man that can see the tops of all. Thus when the sea

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.

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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.
† So A. D. 1547, April 24th to the 28th.

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