[Illustration: The magic mirror.] [Illustration: Fig. 266. Plan of room. A A. The frame of the looking-glass. A B. Mirror put back to an angle of 45 degrees. C. The confederate who manages the lantern and shuts the glass to the frame after each fortune is told. D. The magic circle, to which the rays are reflected.] [Page 279] Does it spring from the education which during many ages the human race has received from its first instructors? A vast and novel question, but with which I have nothing to do. It is sufficient to observe that as the lover of the wonderful always prefers the most surprising to the most natural account, this last has been too frequently neglected, and is irrevocably lost. Occasionally, however (and we shall cite more than one instance), simple truth has escaped from the power of oblivion. Credulous man may be deceived once, or more frequently; but his credulity is not a sufficient instrument to govern his whole existence. The wonderful excites only a transient admiration. In 1798, the French _savans_ remarked with surprise how little the spectacle of balloons affected the indolent Egyptian.... But man is led by his passions, and particularly by _hope_ and _fear_." When parallel rays fall upon a convex mirror, they are scattered and dispersed in all directions, and the image of an object reflected in a convex mirror appears to be very small, being reduced in size because the reflected picture I M is nearer the surface of the mirror than the object A B. No. 1. (Fig. 267.) [Illustration: Fig. 267. A B, D H. (No. 2) represent two parallel rays incident on the convex surface B H, the one (A B) perpendicularly, the other (D H) obliquely. C is the centre of convexity. H E is the reflected ray of the oblique incident one, D H; whilst C H I is the perpendicular.] Convex mirrors are not employed in any optical deception on a large scale, although some ingenious delusions are producible from cylindrical and conical mirrors, and are thus described by Sir David Brewster: