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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, affirnis 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 t, 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. l. 1. c. 7. sect. 11. Meteor. l. 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 mourtain 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 froin A B a 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. But of this in the next chapter.

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, vapo

rous 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 t, 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.

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.

1

Iue etiam extincto miseratus Cæsare Romam,
Cum caput obscura nitidum ferrugine texit,
Impiaque æternam timuerunt sæcula noctem *.
He pitying Rome when as great Cæsar dy'd,
His head within a mourning vail did hide.
And thus the wicked guilty world did fright
With doubtful fears of an eternal night.

Solis quoque

Ovid likewise, speaking of his death,

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 carth.

* Virgil, Georg. I. 1.

+ Metam. lib. 15.

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