Pepper’s ghost is an illusion technique used in theater, amusement parks, museums, television, and concerts. It is named after John Henry Pepper, a scientist who popularized the effect in a famed demonstration in 1862. It has a long history, dating into the 16th century, and remains widely performed today.
Notable examples of the illusion are the ‘Girl-to-Gorilla’ trick found in old carnival sideshows and the appearance of ‘ghosts’ at the ‘Haunted Mansion’ at Disneyland. Teleprompters are a modern implementation of Pepper’s ghost. They reflect a speech or script and are commonly used for live broadcasts such as news programs. Examples of concert illusions based on Pepper’s ghost are the appearance of Tupac Shakur onstage with Dr. Dre and Snoop Dogg at the 2012 Coachella Music and Arts Festival and Michael Jackson at the 2014 Billboard Music Awards.
The basic trick involves a stage that is specially arranged into two rooms, one that people can see into or the stage as a whole, and a second that is hidden to the side, the ‘blue room.’ A plate of glass (or Plexiglas or plastic film) is placed somewhere in the main room at an angle that reflects the view of the blue room towards the audience. Generally this is arranged with the blue room to one side of the stage, and the plate on the stage rotated around its vertical axis at 45 degrees. Care must be taken to make the glass as invisible as possible, normally hiding the lower edge in patterning on the floor and ensuring lights do not reflect off it.
When the lights are bright in the main room and dark in the blue room, the reflected image cannot be seen. When the lighting in the blue room is increased, often with the main room lights dimming to make the effect more pronounced, the reflection becomes visible and the objects within the blue room seem to appear in thin air. A common variation uses two blue rooms, one behind the glass and one to the side, which can be switched visible or invisible by alternating the lighting.
The hidden room may be an identical mirror-image of the main room, so that its reflected image matches the main rooms; this approach is useful in making objects seem to appear or disappear. This illusion can also be used to make one object or person reflected in the mirror appear to morph into another behind the glass (or vice versa). This is the principle behind the Girl-to-Gorilla trick found in old carnival sideshows and in the James Bond movie ‘Diamonds Are Forever.’ The hidden room may instead be painted black, with only light-colored objects in it. In this case when light is cast on the room, only the light objects reflect the light and appear as ghostly translucent images superimposed in the visible room. This can be used to make objects appear to float in space.
Giambattista della Porta was a 16th-century Neapolitan scientist and scholar who is credited with a number of scientific innovations, including the camera obscura. His 1584 work ‘Magia Naturalis’ (‘Natural Magic’) includes a description of an illusion, titled ‘How we may see in a Chamber things that are not’ that is the first known description of the Pepper’s ghost effect.
Porta’s description, from the 1658 English language translation, is as follows: ‘Let there be a chamber wherein no other light comes, unless by the door or window where the spectator looks in. Let the whole window or part of it be of glass, as we used to do to keep out the cold. But let one part be polished, that there may be a Looking-glass on bothe sides, whence the spectator must look in. For the rest do nothing. Let pictures be set over against this window, marble statues and suchlike. For what is without will seem to be within, and what is behind the spectator’s back, he will think to be in the middle of the house, as far from the glass inward, as they stand from it outwardly, and clearly and certainly, that he will think he sees nothing but truth. But lest the skill should be known, let the part be made so where the ornament is, that the spectator may not see it, as above his head, that a pavement may come between above his head. And if an ingenious man do this, it is impossible that he should suppose that he is deceived.’
The Royal Polytechnic Institute London was a permanent science-related institution, first opened in 1838. With a degree in chemistry, John Henry Pepper joined the institution as a lecturer in 1848. The Polytechnic awarded him the title of Professor. In 1854, he became the director and sole lessee of the Royal Polytechnic. In 1862, inventor Henry Dircks developed the ‘Dircksian Phantasmagoria,’ his version of the long-established phantasmagoria performances. This technique was used to make a ghost appear on-stage. He tried unsuccessfully to sell his idea to theaters. It required that theaters be completely rebuilt to support the effect, which they found too costly to consider. Later in the year, Dircks set up a booth at the Royal Polytechnic, where it was seen by John Pepper.
Pepper realized that the method could be modified to make it easy to incorporate into existing theatres. He first showed the effect during a scene of Charles Dickens’s ‘The Haunted Man,’ to great success. Pepper’s implementation of the effect tied his name to it permanently. Dircks eventually signed over to Pepper all financial rights in their joint patent. Though Pepper tried many times to give credit to Dircks, the title ‘Pepper’s ghost’ endured. The relationship between Dircks and Pepper was summarized in an 1863 article from ‘Spectator’: ‘This admirable ghost is the offspring of two fathers, of a learned member of the Society of Civil Engineers, Henry Dircks, Esq., and of Professor Pepper, of the Polytechnic. To Mr. Dircks belongs the honor of having invented him, or as the disciples of Hegel would express it, evolved him from out of the depths of his own consciousness; and Professor Pepper has the merit of having improved him considerably, fitting him for the intercourse of mundane society, and even educating him for the stage.’
The Daily Omnivore 
Leave a Reply