The North Carolina School of Science and Mathematics hosts an informative online exhibit about several optical toys and "illusionary devices" from before the twentieth century. From the description of Magic Lanterns, like the one pictured here:
"A magic lantern consists of seven functional sections: the lamp, reflector, condensing lens, lens tube, body, base, and smokestack. The lamp is the sole source of illumination, which often came from burning oil or gas, a burning piece of calcium, or later, electricity. The reflector reflects the light from the lamp toward the condensing lens, which focuses the light onto the slide being projected. The lens tube serves to magnify the illuminated slide, so that projected images from 6 to 12 feet wide can be obtained. The body is often made completely of metal, and houses all of the previous components except the lens tube. The base lifts the magic lantern above the surface of a table. This is important because the body will become intensely hot from the illuminating lamp, and the base helps to prevent table burns. Finally, the smokestack serves to vent the smoke coming from the lamp, so that the smoke doesn't accumulate inside the lantern and put out the fire."
Link (via MetaFilter)
