When, in 1866, Robin’s Spectres were taken to a large theatre in Paris, the Châtelet, he was obliged to devise a different arrangement, for the spectators in the galleries above were able {100} to see, at the same time, both the actor and his reflection. Robin had been obliged to place his actor on a lower level because he had no room at the side of his little stage. At the Châtelet, however, space permitted a much more convenient arrangement, for it allowed the actor, who furnished the reflection, to move about freely on a horizontal plane. The glass was placed vertically and formed, on the plane, an angle of about 45° with the longitudinal axis of the theatre. The actor was hidden behind a wing; his reflection appeared in the center of the stage toward the back-drop; visible, nevertheless, to all the spectators. His field of movement, necessarily restricted, was marked out in advance upon the floor. Robin was able to preserve for a considerable time the secret of the ghost illusion; just enough to pique the curiosity of the public. It was guessed at last that he made use of unsilvered glass. The fact became known and several wags proved the presence of the glass by throwing inoffensive paper balls which struck the obstacle and fell, arrested in their flight. Robin was greatly vexed at these occurrences but the trick was none the less exposed. III. Pepper eventually brought out a new illusion called “Metempsychosis,” the joint invention of himself and a Mr. Walker. It is a very startling optical effect, and is thus described by me in my American edition of Stanyon’s _Magic_: “One of the cleverest illusions performed with the aid of mirrors is that known as the ‘Blue Room’, which has been exhibited in this country by Kellar. It was patented in the United States by the inventors. The object of the apparatus is to render an actor, or some inanimate thing, such as a chair, table, suit of armor, etc., visible or invisible at will. ‘It is also designed,’ says the specification in the patent office, ‘to substitute for an object in sight of the audience the image of another similar object hidden from direct vision without the audience being aware that any such substitution has been made.’ For this purpose employ a large mirror—either an ordinary mirror or for some purposes, by preference, a large sheet {101} of plate-glass—which is transparent at one end and more and more densely silvered in passing from this toward the other end. Mount this mirror or plate so that it can, at pleasure, be placed diagonally across the stage or platform. As it advances, the glass obscures the view of the actor or object in front of which it passes, and substitutes the reflection of an object in front of the glass, but suitably concealed from the direct view of the audience. [Illustration: FIG. 1. APPARATUS. FIG. 2. ARMOR SCENE. DIAGRAM OF BLUE ROOM.]