In this box place two mirrors, 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 sides of this box with four oval frames, and transparent glasses, and cover each of them with a curtain, so contrived that they may all draw up together.
Place four persons in front of the four sides, and at equal distances from the box, and then draw up the curtains, that they may see themselves in the mirrors; when each of them, instead of his own figure, will see that of the person who is next him, and who, at the same time, will seem to him to be placed on the opposite side. Their confusion will be the greater, as it will be very difficult for them to discover the mirror contained in the box. The reason of this phenomenon is evident; for, though the rays of light may be turned aside by a mirror, yet they always appear to proceed in right lines.
The Wonderful Phantoms.
In a partition make two apertures of a foot high, and ten inches wide, and about a foot distant from each other. Let them be at the common height of a man’s head; and in each of them place a transparent glass, surrounded with a frame, like a common mirror.
Behind this partition place two mirrors, inclined to it in an angle of forty-five degrees (that is, be halfway between a line drawn perpendicular to the ground and its surface); let them be both eighteen inches square; let all the space between them be enclosed by boards, or pasteboard, painted black, and well closed, that no light may enter. Let there be also two curtains to cover them, which may be drawn aside at pleasure.
When a person looks into one of these supposed mirrors, instead of seeing his own face, he will perceive the object that is in front of the other; so that, if two persons present themselves at the same time before these mirrors, instead of each one seeing himself, they will reciprocally see each other.
Note.—There should be a sconce, with a candle placed on each side of the two glasses in the wainscot, to enlighten the faces of the persons who look in them; otherwise this experiment will have no remarkable effect.
This curious trick may be considerably improved, by placing the two glasses in the partition in adjoining rooms; and, a number of persons being previously placed in one room, when a stranger enters the other, you may tell him his face is dirty, and desire him to look in the glass, which he will naturally do; and on seeing a strange face he will draw back; but, returning to it, and seeing another, and another, like the phantom kings in Macbeth, what his surprise will be is more easy to conceive than express. After this, a real mirror may be privately let down on the back of the glass, and, if he can be prevailed to look in once more, he will then, to his further astonishment, see his own face, and may be told, perhaps persuaded, that all he thought he saw before was mere imagination.
How many tricks, less artful than this, have passed in former times for sorcery, and pass at this time, in some countries, for apparitions!
Note.—When a man looks in a mirror that is placed perpendicular to another, his face will appear entirely deformed. If the mirror be a little inclined, so as to make an angle of eighty 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 sixty 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 glass comes to forty-five 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, their different inclinations will produce other effects, as the situation of the object relative to these mirrors is quite different.