This slide consists of two revolving glass discs, rotating in opposite directions. Both glass discs are 65 mm (2 ¾ inches) in diameter, each with rack-work rim. The discs are held together by a wide brass rim and are rotated through a wooden handle connected to a steel pinion with toothed-end. The whole is assembled on a wooden frame 16 X 9 cm (6 ½ X 3 ½ inches). The glass discs are painted in blue, red, yellow and black arcs and their rotation produces a dazzling kaleidoscopic effect.