Magic Lantern, machine invented by Father Kircker, Jesuit, [1] that has the property of making small figures painted on thin pieces of glass appear larger on a white wall, and with fully transparent colors. [2] 

For this effect, one places a strong light behind the painted glass, on which is placed the representation of the object, and in front, some distance away from the glass, one places two lenticular lenses that have the property of separating the rays that leave the object, of making them diverge, and consequently projecting on the opposite wall a representation of the image that is much larger than the object. Ordinarily, one places these two lenses in a tube, where they are mobile, so that one can move them closer together or farther apart sufficiently to render the image distinctly on the wall.

This tube is attached to the front of a square box within which is the object-holder; and so that the lantern makes an even greater effect, a spherical mirror is placed in the same box, whose light occupies the foyer; and in front of the object-holder, between it and the light, a third lenticular lens is placed. Ordinarily, one slides the object-holder by using a runner operated at M close to the third lenticular lens. See [plate 1] figure 10 of Optics, where you will see the shape of the magic lantern . N O is the object-holder, on which are painted different figures that we know how to pass successively between the tube and the box, as represented in the figure.  On the magic lantern , we can consult the physics essay of Mr. Musschenbroek section 1320 and following, and the Leçons de Physique of the Abbé Nollet, book V near the end.  [3] The theory of the magic lantern is founded on a simple proposition; if one places an object a little beyond the foyer of a lens, the image of this object will be found on the other side of the lens, and the size of the image will be the same as the object, more or less as the distance between the image and the lens is the same as that between the object and the lens. See Lens . Thus, we can make magic lanterns with one lenticular lens; the multiplication of these lenses serves to augment the effect.

1. Athanasius Kircher (1602-1680), who came up with the idea but did not invent the actual machine. See Magic lantern.

2. There are many similarities between the original French text and the entry for “Magic Lanthorn” in Chambers’s Cyclopaedia (1728).

3. Peter Van Musschenbroek (1692-1761) was a Dutch physicist known for his discovery of the Leyden Jar, the first capacitor. French clergyman and physicist Jean-Antoine Nollet (1700-1770), also known as Abbé Nollet, was known for his research in electricity. There were many editions of his Leçons de physique expérimentale in the eighteenth century; this one was published in Paris in 1764.