Part 18 (1/2)
_The Enchanted Palace._
On the six-sided plane A B C D E F, Fig. 21, draw six semi-diameters; and on each of these place perpendicularly two plane mirrors, which must join exactly at the centre, and which, placed back to back, must be as thin as possible. Decorate the exterior boundary of this piece, (which is at the extremity of the angles of the hexagon,) with six columns, that at the same time serve to support the mirrors by grooves formed on their inner sides. Add to these columns their entablatures, and cover the edifice in whatever manner you please. In each one of these six triangular s.p.a.ces, contained between two mirrors, place little figures of pasteboard, in relief, representing such subjects, as, when seen in an hexagonal form, will produce an agreeable effect.
To these add small figures of enamel, and take particular care to conceal by some object that has no relation to the subject, the place where the mirrors join, which, as before observed, all meet in the common centre.
[Ill.u.s.tration: Fig. 21.]
When you look into any one of the six openings of this palace, the objects there contained, being reflected six times, will seem entirely to fill up the whole of the building. This illusion will appear very remarkable, especially if the objects chosen are properly adapted to the effect which the mirrors are intended to produce.
If you place between two of these mirrors part of a fortification, as a curtain, and two demi-bastions, you will see an entire citadel with six bastions; or if you place part of a ball-room, ornamented with chandeliers and figures, all these objects being here multiplied, will afford a very pleasing prospect.
_Opaque Bodies seemingly Transparent._
Within the case A B C D, place four mirrors O P Q R, Fig. 22, so disposed, that they may each make an angle of 45 degrees, that is, that they may be half-way inclined from the perpendicular, as in the figure. In each of the two extremities A B, make a circular overture; in one of which fix the tube G L, in the other the tube M F, and observe, that in each of these is to be inserted another tube, as H and I. [_Observe._ These four tubes must terminate in the substance of the case, and not enter the inside, that they may not hinder the effect of the mirrors. The four-fold reflection of the rays of light from the mirrors, darkens in some degree the brightness of the object; some light is also lost by the magnifying power of the perspective.
If, therefore, instead of the object-gla.s.s at G, and concave eye-gla.s.s at F, plain gla.s.ses were subst.i.tuted, the magnifying power of the perspective will be taken away, and the object appear brighter.]
[Ill.u.s.tration: Fig. 22.]
Furnish the first of these tubes with an object-gla.s.s at G, and a concave eye-gla.s.s at F. You are to observe, that in regulating the focus of these gla.s.ses with regard to the length of the tube, you are to suppose it equal to the line G, or visual pointed ray, which entering at the aperture G is reflected by the four mirrors, and goes out at the other aperture F, where the eye-gla.s.s is placed. Put any gla.s.s you please into the two ends of the moveable tubes H and L; and lastly, place the machine on stand E, moveable at the point S, that it may be elevated or lowered at pleasure.
When the eye is placed at F, and you look through the tube, the rays of light that proceed from the object T, pa.s.sing through the gla.s.s G, are successively reflected by the mirrors O P Q and R to the eye at F, and there point the object T in its proper situation, and these rays appear to proceed directly from that object.
The two moveable tubes H and I, at the extremity of which a gla.s.s is placed, serve only to disguise the illusion, for they have no communication with the interior of the machine. This instrument being moveable on the stand E, may be directed to any object; and if furnished with proper gla.s.ses, will answer the purpose of common perspective.
The two moveable tubes, H and I, being brought together, the machine is directed towards any object; and, desiring a person to look at the end F, you ask him if he sees that object distinctly. You then separate the two moveable tubes, and, leaving s.p.a.ce between them sufficiently wide to place your hand or any other solid body, you tell him that the machine has the power of making objects visible through the most opaque body; and as a proof, you desire him to look at the same object, when to his great surprise he will see it as distinctly as if no solid body interposed.
This experiment is the more extraordinary as it is very difficult to conceive how the effect is produced; the two arms of the case appearing to be made for the purpose of supporting the perspective-gla.s.s; and to whatever object it be directed, the effect is still the same.
_The Deforming Mirrors._
If a person look in a concave mirror placed perpendicularly to another, (that is, supposing one mirror to be laid on the floor, and the other attached to the ceiling,) his face will appear entirely deformed. If the mirror be a little inclined, so as to make an angle of 80 degrees, (that is, one-ninth part from the perpendicular,) he will then see all the parts of his face, except the nose and forehead.
If it be inclined to 60 degrees; (that is, one-third part,) he will appear with three noses and six eyes: in short, the apparent deformity will vary at each degree of inclination, and when the gla.s.s comes to 45 degrees, (that is, half-way down,) the face will vanish. If, instead of placing the two mirrors in this situation, they are so disposed that their junction may be vertical, then different inclinations will produce other effects, as the situation of the object relative is quite different.
_The Magic Tube._
Procure a small tube of gla.s.s, whose ca.n.a.l is extremely narrow, and open at both ends; let one end of it be plunged in water, and the water within the tube will rise to a considerable height above the external surface: or if two or more tubes be immersed in the same fluid, the one with a narrow ca.n.a.l, and the other wider, the water will ascend higher in the former than the latter.
_The Magician's Mirror._
Construct a box of wood, of a cubical shape, A B C D, Fig. 23, of about fifteen inches every way. Let it be fixed to the pedestal P, at the usual height of a man's head. In each side of this box let there be an opening, of an oval form, ten inches high, and seven wide. In this box place two mirrors, A D, with their backs against each other.
Let them cross the box in a diagonal line, and in a vertical position.
Decorate the openings in the side of this box with four oval frames and transparent gla.s.ses, and cover each with a curtain so contrived as all to draw up together.