lens, which transmits the rays proceeding from the object. The image is reflected in that mirror, and the rays issuing from it are thrown up against the flat plate of ground glass placed to receive them. The objects which are reflected in the highest part of the sloping mirror, are transmitted to that part of the flat glass above, which answers to the bottom of a picture, and this simple expedient restores them to an apparently upright posture. Here, then, you may presently see a perfect miniature resemblance of a person sitting at the other end of the room; a picture which painting cannot equal; for it may speak to, or smile upon you, while you watch every varying expression of the countenance. Or, if by daylight you place the machine before a window, you will have an animated representation of every object before it. I have heard that George Smith, of Chichester, (a painter who obtained great celebrity by his accurate representations of nature, as she appears in our Sussex landscapes,) used to walk about the hills with a camera-obscura, MAGIC-LANTERN. 177 which enabled him to study in detail such objects as were worthy of notice: light, shade, colouring and perspective, were thus placed before him in small, but most faithful pictures. All who have eyes, and can use them, may be charmed with the representations of the camera. A Malayan chief, in the island of Sumatra, was so delighted with the instrument, when he first beheld it in the possession of a traveller, that he seemed inclined to offer in exchange for it almost any thing he possessed.* You are sometimes amused by the varied exhibitions of the magic-lantern; but, perhaps, may not quite understand how the effect is produced. I will endeavour to explain it. A lamp is placed within the machine, and a concave mirror fixed behind the lamp, which causes a very bright reflection of the rays issuing from it to pass through a lens placed in the sliding tube. The slips of clear glass, on which the objects are painted, are placed in the tube *Arnott, El. Phys. ii. 199. 178 PHANTASMAGORIA. between the lamp and the lens, in an inverted position; and the rays proceeding from these little pictures, after passing through the lens, (which restores the objects to an upright posture,) form magnified images, appearing in circles of light, on the sheet, or screen, which is placed to receive them. If the screen were made of thin silk, and placed between the lantern and the spectators, and if the slips of glass were so painted that no light could pass except through the figures—the image only would be visible, and appear as if it were formed in the air. By removing the lantern farther from the screen, or bringing it closer to it, the figure would be enlarged or diminished, and therefore appear as if it advanced towards the spectator, or retired to a distance. Such a representation is called a phantasmagoria.* * Joyce, vol. v. p. 220–223. |