The first thing is the explanation of how the man becomes released from the shackles. It principally lies in the construction of the board. There is no deception about the keys, locks, or manacles, since it is not at all necessary to the deception that there should be. The board is hollow and contains cunningly concealed levers, four in number, which move simultaneously. The eyes that the manacles slip over, and to which the locks are fastened, go into the board and are held fast by the ends of these levers, which enter a hole or notch, as the case may be, in the eye. The shackles and neck piece and their respective eyes are all made fast to an iron plate or bed which is bolted to the board; a bolt at each corner of the plates goes through the board and secures another plate at the bottom of it, making all firm. There is one bolt, however, that does not go through; it is riveted to one of the short levers, and by its means the system of levers is pushed backward or forward. There is a nut on the bottom plate to make it appear as if this identical bolt went completely through, the same as the others. The levers run in grooves made in any suitable part of the board and covered by a strip of wood or other material, thus rendering the mechanism invisible, and appearing as if the board was solid.
FIGS. 4-7.—DETAILS OF THE MECHANISM.
FIG. 8.—THE ESCAPE OF THE PRISONER.
At each corner of the board is a ring or screw eye, into which the chain provided with a hook is secured, by which to suspend the board. The four levers are pivoted to a rocking lever in the center of the board, which is likewise pivoted. By this means all the levers are moved simultaneously. When the lever is moved it releases all the shackles, and the prisoner is then, of course, free, and it is but the work of a moment to climb out through an opening in the scene at the back, where the lady who is to take his place is now waiting on the end of a long board pushed out through the opening in the scene. The lady gets on the trick board, the man slams the shackles into place, moves the bolt back, thus shoving the levers back into their notches in the eyes, again making everything fast, makes his escape through the scene, and appears a minute later from the front of the theater.
The trick is varied sometimes by using double curtains at the back; concealed between them is the lady. After the exchange the man hides in the same place, and another man, his exact counterpart, is the one who makes his appearance in the audience.