Natural Magick. c BooJ^ 17.
upon the ground; then place your eye ar some hole or chink that is somewhat di-stant from the Glass, and let it be fixed, that it may not move here and there: overagainst the Glass break the wall, and make it like to a window : let it be Pyramidalin shape, and let the sharp point be within, and the basis without, as men use todo, when a Picture or any Image is placed for the Cye to look upon; but let it bereflected on by the superficies of the Pyramidal Glass, that the Picture placed with-out, which your eye cannot fee through the hole, may seem to hang pendulous inthe Air; which will cause admiration to behold. A Pyramidal Convex-glass willdo the same, if you fit it so that it may represent the fame Image. It may be donealso by a Sphæiical Convex apd Concave. But the matter promifeth more in theFrontispiece written upon it, then it will performe in the conclusion. Whereforethe Image will be seen without the Glass, but by the means of the Glass ; so thatthe thing beheld in the Glass, will seem to be without it. But he is foully mistakenhere, as in other places. He had said better, by a Cylinder of Crystal: For as apillar it would make an irradiation outwardly, yet it would be worse seen than in thepillar, as I shall shew. But I shall discover what I purposed always to conceal;
That neither the ObjeEl nor (j lass may be /<rr», jet the Image shall seem to hang alone , pen-dulous in the middle os the ( hamber ;
And walking about, you shall behold the Image every where. But is such a thingfit to be discovered to the people? shall I do such an unworthy Act ? Ahlmy pen fallsout of my hand. Yet my desire to help posterity,overcomes; for perhaps from thisgleaning as it were, greater and more admirable inventions may be produced. Letit be so: get not a Spherical Cylinder, ot Convex dissection of a Pyramidal Concave,the portion of which segment is not known; but let it be that which may descendupon his right Angle by a half Cylinder and a square, and is parted by an obliqueA n° le. Of two parts it must be received pendulous, and beneath in the half of itsdiameter it is conveyed from the middle. Let all the windows of the house be(hut: stop all the chinks, that the light may not come in beneath. In that placewhere the spectacle is prepared, if the Sun ot Moon beams fall in, the whole stiew isspoiled. So place the beams of the Image that are beaten back , that the head of icmay by repercussion fall right upon the earth. So will the visible Object that ccmesby repercussion, be reflected above and beneath; It will follow the fashion of thefirst Glass: let a Brass or Marble Table be so placed upon it, as we said ; and lestthe light falling from the window should light upon the plain Cylinder, and thecrooked Glass, it mu 1 be stopped by a shutter of a hands-breath, that is three timesas broad as the hole ; for it will break forth every way : You shall cover the appari-tion, that the Image may be fitted very deep, that there may seem to be a pic: as thebeams meet, let the spectator come, w ho cannot be in any great mistake. But covervour sight r und,that the Glass offend noc yonr eye. Then is the Image seen, and itshall not appear above the Table, where the falling of the Catheters will cut theline of sight through the Centre of the Glass, I could open the matter no plainer,I have done what I could ; I know he that can understand it,willrejoyccvery much.
Chap, IX.
Mixtures of Glajfec, and divers apparitions of Images.
N Ow will I try to make a Glass, wherein many diversities of Images (hall appear:
and though such a one be hard to make,yet it will recompence all by the di-versity of Images, and the benefit of it. If then you would
Mafy a Cjlxss thatjhallrepresent much diversity os Images.
Take a great or small circle, as you would have your Glass, and here and there cutoff two parts of the circumference, one to the quantity of a Pentagon, the other ofa Hexagon , asls clear in the Mathematicks: let the arch of the Pentagon be madehollow with some table, or Iron, that it may exactly receive ic into it, and may seem