Kaleidoscope, ka-li'do-skop, an optical toy. The name is from the Greek and signifies a beautiful view. The instrument was invented by Sir David Brewster about 1815. It consists essentially of a brass or paper tube, from four to twelve inches in length, shaped like a telescope. Two strips of mirror nearly as long as the tube are placed within it and cemented together at any angle, as 120 deg, which is a submultiple of 360 deg. At one end of the tube is a small eye hole fitted with clear glass so arranged as to bring the eye as nearly as possible in the plane of both mirrors. The other end of the tube is closed with what is called the object-box. This consists of two disks of glass, one against the end of the mirrors and the other at the end of the tube, the two thus forming a little box or cage in which a number of beads, bits of colored glass, or other diaphanous substances are inclosed. The object-box is just large enough to permit the inclosed objects to change position freely. On looking through the tube these bright objects are seen multiplied as many times as the angle of the reflecting surface, is contained in the whole circumference of a circle. For instance, if the mirrors be placed in the tube at an angle of sixty degrees the figures will appear six times, all symmetrically arranged about a point which is the center of the circle bounded by the tube. The outer glass of the box or cage holding the bits of glass is ground so as to prevent interference of outside objects without obstructing the light. The richer the colored objects, the more beautiful the effect. Tiny glass tubes partially filled with liquid and hermetically sealed, slender threads of twisted glass, bits of netting woven of gold wire,--all produce fine effects. If the tube be twirled slowly the objects shift into new positions and an almost infinite variety of patterns is obtained. In fact, the kaleidoscope is employed to obtain suggestive patterns for decorative work. See TOY.