Iriscope

Apparatus contrived by Read for producing colored rings, similar to Newton's rings, by interference of light. If a little soap be rubbed on a piece of black gla , and the breath be blown upon a small area of this through a tube, a transparent film will be deposited, decreasing in thickne from the center outward. Rays of light reflected from the two surfaces of this film i ue in different phases, and so are in a condition to interfere. The interference of the different colored rays depending upon the thickne of the film, the bright rings will be colored, the le refrangible rays being within and the more refrangible on the outside.