CHAPTER VIII

OPTICAL PRINCIPLES

AMONG principles of the optical type, the first is Mirror Masking. It is well known in connect-ion with devices such as "The Sphinx," where mirrors radiating from the center of a curved: or polygonal recess, and having their edges hidden by the legs of a table, are used to conceal a person behind them.

The Reflected Image principle is the converse of the preceding. Instead of masking an object, the mirrors serve to make an object appear where, in reality, none exists. The illusion introduced by Professor Pepper at the London Polytechnic, and known to magicians as "The Walker Illusion," illustrates this principle excellently.

With Professor Pepper and the Polytechnic is also associated the introduction of Transparent Reflectors. The mention of "Pepper's Ghost" is a sufficient description of the method and its mode of application to magical purposes.

Lantern Projection has been employed in magic, almost from the date of its invention by Kircher. It is, however, seldom employed by modern magicians. Except in an unusually clear atmosphere, the beam of light from the lantern is so distinctly visible, and the need for complete or semi-darkness so objectionable, that the possibilities of this principle are limited within very narrow bounds.

Background Work is the principle of masking by means of a screen, having the same color as a plain background against which it is seen. It has long been used in small effects, such as the appearance of objects within frames with black centers; the objects produced being temporarily concealed by pieces of black material, snatched away at the proper moment. Its adaptation to stage illusions proper was made by de Kolta, at the Egyptian Hall, London, in 1886. The title of "Black Magic," adopted by him for the act in which this invention was employed, has since become a technical term, denoting the use of the background principle with black material. In this sense, however, the term is liable to create false impressions. Firstly, it suggests that the use of black against black, in any way whatever, is a device which de Kolta claimed to have invented. Secondly, it suggests that de Kolta's invention was limited to black alone. Such ideas are by no means in accordance with the facts. Reference to de Kolta's patent will show that his invention relates to the obliteration of visible contour by the destruction of shadow, and that any color whatever may be used in connection with it. In practice, the distinction between de Kolta's invention and previous applications of this principle may be said to consist in the production of effects upon a large scale, as compared with the concealment of small objects.

Chiaroscuro is a principle depending upon variations of shade and tint for the creation of deceptive appearances. The painting of a flat surface to resemble a concavity or convexity will represent an application of this principle. Similarly, the disguising of a hollow or projection to resemble a plain surface will equally fall within this category of devices. An example is the sunken cavity, used as a receptacle for small articles, in what appears to be a flat table-top, decorated with a painted or inlaid pattern.

Previous | Next | Contents