An interchangeable cell for David Brewster's kaleidoscope, invented in 1816. The cell contains fragments of colored glass between two glass faces, one of transparent glass, which faces the viewer when inserted, and one of ground glass, which faces the source of light and diffuses it. Brewster experimented with a variety of objects in addition to glass fragments, including metal wires, beads, lace, hand-drawn figures and transparent paint (Brewster 1819, 68).

As with Charles Wheatstone, the inventor of the stereoview, Brewster's primary interest was scientific. He invented the kaleidoscope while investigating the polarization and refraction of light. He gave Philip Carpenter (who later developed a transfer process for producing magic lantern slides) rights to manufacture kaleidoscopes, but in the face of skyrocketing demand, he soon licensed 16 other manufacturers. Years later his daughter Margaret Maria recalled:

This beautiful little toy, with its marvelous witcheries of light and colour, spread over Europe and America with a furor which is now scarcely credible. …[but] as it often has happened in this country, the invention was quickly pirated, and thousands of pounds of profit went into other pockets than those of the inventor, who never realized a farthing by it (Gordon 1870, 97).