This mechanical lantern slide has a wooden frame, and a glass disc divided into fourteen (or twice seven) segments, each representing a color of the rainbow; when the disc is rotated rapidly, it appears white.
In the optical experiments that he described to the Royal Society in 1672, Isaac Newton showed that a prism would disperse sunlight into a spectrum, and identified what he deemed the seven basic colors of this spectrum. In his Opticks (London, 1717), Newton discussed the persistence of vision, noting that a burning coal moved quickly in a circle appears as a continuous circle. Newton’s Color Disc combines these two ideas.
Ref: Lorenzo Marcy, The Sciopticon Manual (Philadelphia, 1877), p. 31.