Who has not heard of all the wonders of the magic lantern?—how little figures painted upon glass become magnified into big comic men and women when seen upon the screen. It is not only a very amusing toy, but a very philosophical instrument, and we dare say that the inventor, Kircher, who was a celebrated mathematician and philosopher in the seventeenth century, little thought that children would be amused with it, because he intended it to be an object of study for the monks in their cells. This Kircher was an extraordinary man, he knew a great deal more than was common among his fellow monks, and he lias since been called a man of "immense but undigested learning ;" because he made the most extraordinary and random statements upon the deepest questions of philosophy. In one city of Europe, Nuremberg, many thousands of cheap magic lanterns are made every year, and they afford winter evenings' enjoyment to the children of the whole civilized world. We will now describe the construction of this instrument, having reference to the engraving, which is a section of a magic lantern. A is a box of wood or metal having a chimney, B, and a handle, C. In a round hole in the front is placed a piece of glass called a lens, of convex form, that is, its back is flat and its front side is rounded from the center to the edges, as seen at D; this is called the condenser, because it collects or condenses the rays of light from the lamp, G, which is placed inside the lantern, A. Beyond D is a sliding tube, having at its extremity a lens, F, which is double convex, or rounded at both its sides, in short, a magnifying glass. In a slit in this tube, the glass slide, E, having the figure, a picture, painted on it, is inserted upside down, and a white sheet being stretched across one end of a room, and all the lights, save the lantern, turned out, the exhibition is ready to commence. "Ah! but," says some young inquisitive who has seen the magic lantern's wonders, " bow is it that yon see the funny things so largo upon the sheet when they are so little on the slide ?" We will tell you. The light from the lamp has no escape except through the condenser, which throws a strong light upon and through the colors on the slide, and these colored rays, being confined by the tube, arc passed through F, which spreads them . out and so makes them meet each other at what is called the focus of the lens (of which we shall liava more to say next week), and throws them very large upon the sheet, and there being no other light in the room, they become visible right side up, because the rays have been turned round or reversed by the leu?, and it depends upon the distance of the lantern fromthe sheet whether the figures are large or small.
This article was originally published with the title "Science in Sport" in Scientific American 13, 27, 216 (March 1858)