^8 Natural Magick. 17.

A (frystal Sphere, or portion of it.

And if a Sphxre be wanting, we may supply it with a Vial full of water , that isround and of Glass, set against the Sun : if you set behind it any combustible mat-ter, that is friendly to the fire , so soon as the rays unite about the superficies, icforthwith Itindleth fire , to the wonder of the Spectators : when they fee fire rai-sed from water,that is extreme cold, so will the portions of Sphxres, as spectacles,lenticular?, and such like, which we speak of already.

A Crystal par abolick?G last will kindle fire most vehemently of aU,we (hall see it,because the beams all meeting, it kindles more than a Glass. We mayalso, as I said of a Glass

By refraction, kindle fire asar off,

And almost terfefinite distance, as is demonstrated by Obtick reasons • and the woreby how much as refractions work more forcibly than reflections: and I {hallper-form this many ways , as I said before, not onely by reason, but by experience.Almeen said, That he made the same way parallel lines cut across. I have said also,that if they be opposed in place, Crystal Sphxres are so perfectly opposite by coition,as are Sphxral and Cylindrical portions. Nor do they cast forth fire so far, that itis hard to believe k, and more than imagination can comprehend. Behold,! shall{hew you a more forcible way to kindle fire. It sends forth also uneqnal, and com-bust parallels. Let a uniform Section fall in, and it will carry forth oblique beams,yeushall fee the fire by a hidden and open beam, falling upon a right superficies, andit will ceme Forcibly and uniformly into that place , where the beams unite most ina fit combustible matter: sorts that combustible matrertbat is opposite, be not dry,it is in vain to set a Glass against it, either a Convex Cylindrical, or Concave Spha-rical; for the matter will be found almost pierced through with strong fire , and if itbe not truly opposite it will burn, whether it be small or great. But it is considera-ble, the portion of which it is. It will do also the same thing, if the thing be op-posite, and be small or great, if need be.

Chap. XX.

In a hollowed Class how the Image may hang without.

B Efore I depart from a plain Glass, it is performed by the later Artists industry,that in the fame Glass many faces may be seen, ot likenesses of the fame Image,without any hindrance to the first dor behind it they make the Glass hollow^md makea little Concave, whence a foil being laid on, as I shall {hew, and fitted well, it willhold another forth without. Hence comes it to pass by this excellent invention,that a man locking in a Glass, may fee the upright Image of feme other thing, andwonders at it, for catching at it, hecan catch nothing hut Air. I remember thatI have often seen it, and the matter is thus. A Glass being made of Crystal, theymake a hollow place on the backside like an Image, as curiously as they can-, thenthey foil it over, and fet it in its place, bow as deep as the hollow is with iu, so tnudhwill it shew it self without the superficies; and you cannot fatisfie your self, unlessyou touch it with your bands, whether it truly stick without the Glass or nor. SoLetters are truly read, that they will seem to be made in Silver upon the Crystal; nork the eyes© quick, but it may be deceived when it locks on. Nor will I tswk theArtifice,

To fee in a plain (j lass that which appears no where.

I have often much delighted my friends , and made them admire with this Glass.Provide thirty or forty little Tables ready, ©fa foot and half ]o^, and two fingersbread, and a third part of a finger thick; so artificially hewed, that the thickness

may be upon the one side, and the thinness en the other side, like the edge of a knife.

Piacc