[Gk. kalos, beautiful; eidos, a form; and skopein, to see.] An optical instrument invented by Sir David Brewster in 1817. It consists of a tube' containing two glass mirrors, making an angle of 60° with one another, and extending the whole length of the tube. One end of the tube has a small opening to serve as an eye-glass, and the other end has two glasses, one of ground and the other of clear glass, with little pieces of colored glass lying loosely between them. These colored bits of glass are reflected in the looking-glasses, and regular figures of the most beautiful form, which change -whenever the instrument is shaken, are seen on looking through the instrument. It forms a cheap and pretty toy, and is also used, in a more expensive form, by pattern-drawers and others, who get from it an endless variety of designs.