Electronics

Slide projectors are a modern invention but the underpinnings of such technology date back hundreds of thousands of years to shortly after the discovery of fire. Cavemen used fire as a source of light to project shadows on the cave walls and entertain each other with stories and legends; there were probably some quite accomplished artisans of shadow projection in prehistoric times who were considered indispensable. Over the course of millenia, humans slowly refined the principles of image projection as a storytelling medium.

The First Primitive Slide Projectors
According to unearthed Chinese documents, both the Chinese and Japanese were creating artificial image projection systems as early as the 5th century AD. Their device was called a magic mirror, and used a highly polished bronze disk to reflect light from an image off the mirror and onto a screen of white silk. The first European attempts to duplicate projected effects werent documented until almost a full thousand years later, when in 1420 a drawing in a book by an Italian named Giovanni de Fontana depicted a man bearing a jar-like lantern that seems to be casting a large projected image of the devil on a wall.

Other descriptions of medieval slide projectors began to proliferate. In 1589, Giovanni Baptista della Porta published a book on optics called Magiae Naturalis Libri Viginti, wherein he spoke of an ancient art he referred to as mirror writing. Athanasius Kircher, a German Jesuit priest, embellished della Portas ideas in 1646 in a book in which he described a system of image projection using sunlight or candlelight bouncing off a convex lens.

Finally, in 1650, Dutch scientist Christiaan Huygens, who would achieve immortality in the field of optics for developing the wave theory of light, conceived the idea of the magic lantern with the help of a mathematician named Thomas Rasmussen Walgensten. By 1663, their ideas had caught on to the point where London opticians were selling magic lanterns over the counter. More evolutions steadily followed such as revolving slides, projection clocks, and more sophisticated lenses and mirrors for starker, crisper images. By the late 18th century, these first rudimentary slide projectors were in wide use, and because the technology was still considered inscrutable and rather frightening to most people of the day, they were a popular medium for producing horror shows of eerie lights. These events were known as phantasmagoria shows.