Magic Lantern

Magic Lantern, an optical instrument said to have been invented by Athanasius Kircher in 1646, by means of which magnified images of small pictures are thrown upon a wall or screen. The instrument consists of a lantern containing a powerful argand lamp or lime-light arrangement (see LIME-LIGHT); in the side of the lantern is inserted a horizontal tube, the axis of which is on a level with the centre of the flame, and the light is generally made to pass through the tube by reflection from a concave mirror placed on the opposite side of the lantern. The tube is furnished with two lenses, one at each end; the inner one, the condenser, is a large lens of short focus, to condense a strong light on the picture, which is inserted into the tube, between the lenses, through a transverse slit. The other end of the tube is fitted with a double convex lens, or, better, a corrected combination of lenses, which receives the rays after passing through the picture, and throws them upon the screen or wall. The pictures are formed on glass slides—generally $3\backslash frac\{1\}\{4\}$ inches square—with transparent coloured varnish or by means of photography on a collodion, gelatine, or carbon tissue film on the glass, and must be inserted into the tube in an inverted position, and with the film or painted side nearest the screen, in order that the images may appear erect and unreversed. If the screen on which the image is thrown be at too great a distance, the image will become indistinct from the lessened intensity of the light. This instrument is sometimes used as a toy, but is also frequently employed to produce enlarged representations of astronomical and other scientific diagrams, and enlargements of photographic views, so that they may be well seen by an audience. Phantasmagoria, dissolving views, &c. are produced by a particular manipulation of the same instrument.