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MAGIC LANTERN. 



MAGIC LANTERN. 



414 



have in the Greek ue-y-as, the Latin mag-is and mag-nus, the Persian 

 mi'A, and the Sanskrit mah-at. It is a curious fact that the Hindu 

 grammarians derive mah-at from a verb mah, signifying " to worship." 



(Wilson's Sanskrit Dictionary, under mah-at.) 



MAGIC LANTERN is a species of lucernal microscope, its object 

 being to obtain an enlarged representation of figures, on a screen in a 

 darkened room, by means of the pencils of light issuing from a lamp or 

 candle and passing through a convex lens. 



The instrument consists of a lantern, generally of tin, and of a 

 cubical form, in the interior of which is the light ; and at a perforation 

 in one of the gides is applied a tube projecting horizontally from it. 

 Immediately before the aperture, and within the tube, is a glass lens, 

 often nearly a hemisphere and three or four inches in diameter, serving 

 to condense the light which proceeds from the lamp both directly and 

 by reflexion from a concave mirror attached to the side of the lantern 

 which is directly opposite the aperture : this tube carries within it 

 another, which is also provided with a convex lens, and is capable of a 

 small movement for the purpose of adjustment. 



A groove in front of the lantern and parallel to that front receives a 

 rectangular frame containing the glass plates on which are painted, 

 with transparent colours, the objects of which an enlarged view is to 

 be obtained. Instead of a single convex lens, the sliding tube is some- 

 times provided with two such lenses ; these are placed at a short 

 distance from one another, and have between them a perforated plate 

 of tin, or diaphragm, crossing the Ulterior of the tube, for the purpose 

 of cutting off the more divergent rays which would render the figures 

 indistinct. The lens, or pair of lenses, is of such a focal length that the 

 rays in each of the pencils which proceed from the object may unite 

 on the screen in what is called the conjugate focus, and thus produce 

 the enlarged representation of the figure. 



Several figures are usually drawn on the same plate of glass, and the 

 plate is capable of being moved by hand in the groove so that the 

 different figures may be brought successively before the spectator : for 

 the purpose of heightening the effect, motions can be given to the 

 figures by means of a simple wheel- work. 



The magic lantern is said to have been invented by Kircher, in the 

 17th century; it is described by him in his 'Ars Magna Lucis et 

 Umbnc.' Cellini, however, who died in 1570, describes some magical 

 effects, such as spectres in the midst of ascending smoke, &c., which are 

 easily produced by the magic lantern, so that Kircher, who was not 

 born until the year 1601, was but a re-inventor, or perhaps only a 

 describer of an instrument, the possessors of which would be likely to 

 keep it secret as far as possible. The celebrated Euler proposed to 

 substitute for the lens of the lantern a concave mirror, perforated in 

 the middle like that of a Gregorian telescope : this was to be placed in 

 the interior of the lantern with its polished surface towards the light 

 and its convexity towards the object. The light was to be so disposed 

 that none of it should pass directly through the aperture in front of 

 the lantern so as to fall on the screen ; and that which was reflected 

 from the concave mirror, after falling upon one with a plane surface, 

 was from thence to be reflected in a contrary direction upon the object. 

 The rays in the pencils proceeding from the object were to pass through 

 a lens in the tube, as in the former construction ; and, by converging 

 with greater accuracy to points on the screen, they would have pro- 

 duced a more correct image than that which results from refracted 

 light alone. 



The magic lantern must have been at best an imperfect affair until 

 the invention of the Argand lamp, by Ami Argand in 1789, by which 

 a clean, clear, bright flame was for the first time produced in lamps. 

 It was not, however, until 1802, that any decided improvement was 

 made, and then M. Philipsthal exhibited at the Lyceum in London the 

 form of instrument known as the Phantatmagoria. The lantern itaelf 

 was similar to but larger than that which served for more general 

 purposes ; and the sliding tube which carried the farthest lens had a 

 greater range of motion. The objects to be exhibited were painted 

 upon a glass plate, with this remarkable difference from former 

 attempts, namely, that all the parts not occupied by the figure, were 

 covered with an opaque varnish, so that no light could pass except 

 through the figure, which was thus rendered more brilliant. The 

 machine was placed upon a stage capable of being moved on wheels in 

 a direction perpendicular to the screen on which the objects were 

 represented. The screen was a curtain made of fine muslin or gauze, 

 and covered with varnish so as to be quite transparent : it was 

 stretched in a vertical position across the theatre or apartment ; and 

 this being made quite dark, the spectators occupied the space in front 

 of the screen, while the apparatus was disposed on the opposite side. 



In any magic lantern when the tube carrying the lens which is 

 farthest from the lamp is drawn out as much as possible, the magni- 

 tude of the image represented on a screen is the smallest ; the image 

 increases in magnitude in proportion as the tubes are diminished in 

 length, or as the lens is brought nearer to the body of the lantern. It 

 increases also in proportion as the whole machine is made to recede 

 from the screen ; and the variations of the length of the tubes must, 

 by the exhibitor, be combined with the different distances of the 

 lantern from the screen, in order that by the just convergence of the 

 rays in each pencil, on the screen, the proper degree of distinctness of 

 vision may be obtained under all the variations in the magnitude of 

 the image. The consequence of this is the very serious defect that 



when the image is smallest, and apparently farthest off, it is brightest, 

 and when large, and apparently near, the light is comparatively faint 

 from being spread over a larger surface. This is partially remedied by 

 intercepting a portion of the light, when the image is small and bright, 

 by means of a gauze screen : an ingenious artificial, iris has also been 

 contrived for the purpose. 



Care is taken that during the exhibition all light shall be excluded 

 both before and behind the screen, except that which, in proceeding 

 from the lantern, produces the image to be observed ; and the screen 

 being itself invisible, the spectators can scarcely divest themselves of 

 the idea that they are looking into a dark cavern, in which the objects, 

 at first dimly visible as specks in its deepest recesses, appear to be 

 gradually advancing towards them, increasing in magnitude as they 

 seem to approach : after the objects have been some time apparently in 

 the immediate presence of the company, perhaps surrounded by a blaze 

 of light, they seem as gradually to retire, and at length they vanish, 

 leaving the place in profound darkness. 



Several of these particulars are derived from a ' Treatise on the 

 Magic Lantern,' written in 1854 by Mr. Tomlinson, and published by 

 a maker of the instrument for the benefit of his customers. This 

 treatise lets us into the secret of many of the effects which always 

 excite the admiration, if not the wonder, of the spectators. The 

 following, for example, is the introduction to a description of dissolving 

 views : 



" Dissolving views are produced by means of two magic lanterns 

 of the same dimensions and optical power. They are placed on the 

 same table or horizontal plane, with their lens-tubes inclined towards 

 each other in such a way as to produce a single disc of light upon the 

 opposite wall or screen, instead of two discs, which would be formed 

 if the lens-tubes were parallel. Now it is evident that if by the con- 

 joint action of these two lanterns a disc of light be formed on the 

 screen, the dark shutter of either lantern may be let down, without 

 destroying such disc, but only depriving it of half it light. Suppose, 

 further, that each lantern contained a slider, one representing the 

 exterior of a building, and the other representing the interior, if both 

 lanterns were acting uu the screen at the same time, the super -position of 

 images would produce a confusion which the eye could not unravel ; 

 but if the dark shutter were let down, so as to intercept the light of 

 one lantern, the other would act with full effect. While the spectators 

 are enjoying one view, the shutter of the other lantern is raised, and 

 that of the first is gradually let down ; and it is during this process of 

 moving the shutters that the dissolving effect takes place, because a 

 portion of the light from both lanterns falls upon the screen at the 

 same time ; but the moment one shutter is quite down and the other 

 fully raised the dissolving effect ceases. There is one effect which 

 usually excites a great deal of surprise among the spectators namely, 

 the view of the interior of a large building, deserted and solitary, and 

 while the spectator is gazing, the same building becomes filled with 

 people ; this is produced by painting the same building on two sliders 

 of precisely the same dimensions, and with all the same details in both 

 cases, only in one case empty and in the other full of people ; or as it 

 is not necessary to repeat any part of the painting, one slider may have 

 the building only, and the other the people on a ground of the deepest 

 shade used in the former slide. While the lantern containing the 

 slider representing the empty building is acting on the screen, the 

 shutter of the other lantern is slowly raised, and that of the first as 

 slowly lowered. Thus without any necessary dissolving effect, since 

 the two sliders represent the same object, the empty building appears 

 gradually to fill with people. In the same way a leafless tree covered 

 with snow, may quickly put on the verdure of summer." 



In the following passage the means of producing some of the effects 

 before referred to are described : 



" Many beautiful effects are produced by allowing both lanterns to 

 act together ; one lantern being first employed to produce an effect, 

 and the other being used to heighten it, or to produce some new 

 feature. Thus, for example, a rainbow may be made to appear in the 

 sky of a landscape, as represented by one lantern. For this purpose 

 the landscape without the rainbow is shown by one lantern, and a 

 slider containing only a rainbow, or a &ky and a rainbow, being placed 

 in the second lantern, the shade is removed from it. and the landscape 

 is enlivened by this beautiful addition. By means of a second slider, 

 lightning may also be represented, but in such case the effects of the 

 flash are due to two glasses, both blackened, and containing the same 

 flash of lightning, one of which is fixed and the other moveable. The 

 latter is moved rapidly so as to allow the flash to be seen for an instant 

 and then shaded from view. The dancing of the aurora borealis is pro- 

 duced in a similar way. The whirling of smoke issuing from a volcano 

 is produced by a painting set in a circular brass frame, and capable of 

 revolving round and round by means of a little cog-wheel fitting into 

 the teeth of a circular rack. On tuniing a handle which projects from 

 the side of the slider, the cog-wheel is made to revolve, and this gives 

 motion to the ring of teeth to which the painting is attached. In this 

 way the smoke appears to whirl out of the crater of the volcano, and 

 to be dissipated by the wind. An effect which produces great surprise 

 is that of falling snow. This is managed by a piece of black silk per- 

 forated with holes formed into a roll, mounted in a mahogany frame, 

 and used as a slider, as the paintings are. By means of a small pro- 

 jecting handle at the side the silk can be wound upon another roller, 



