Observation.—If a part of a fortification is mounted between two of the mirrors, such as a curtain and two demi-bastions, the entire citadel will be seen, surrounded by six bastions; apportion of a ball-room, with a quadrille party and one gaselier, will be multiplied, and so on.
The construction can be made on a triangular or square base, and is equally agreeable; but as only three or four subjects can be shown, and the parts of those subjects are parallel with the sides of the temple, and therefore take a form like that at its base, the result is not so wonderful.
Fig. 125.
THAUMATROPE, OR WONDER TURNER.
Cut out a disc of cardboard or pasteboard, and drill three holes near the edge on two opposite sides, in each of which tie a length of string. In the centre on one side paint a jockey seated, and on the other centre, upside down as compared with the man, a running horse.
Performances.—If you take the strings, one set in each hand, and whirl the disc round as on a horizontal axle, the strings will twist and keep up the movement, during which the two pictures will unite as one. Other objects may be a bird and cage, a juggler doing the knife or ball tossing trick, a rat and trap, &c.
THE ARCADE OF VERDURE.
(Unter den Linden.)
Make a box half as wide and high as long. At one end place a mirror, exactly the size of the board, and fixed firmly against it, and remove the quicksilver within a circle agreeing with an eyehole cut in the end. Back the opposite end in the same way with a plane mirror.