CLAVILUX, a keyed projection instrument which makes possible the use of light as a medium for aesthetic expression. It was invented by the American artist, Thomas Wilfred, who gave the new art of light its first comprehensible status with the theory that form, colour and motion are its three basic factors. The in strument consists of a number of projectors grouped before a large white screen and controlled from a keyboard that is either attached to the projectors or placed at a distance. The keys, which slide in grooves graduated from o to 10o, are grouped in tiers, each comparable to a pipe-organ manual. A tier contains three sets of keys connected with the form, colour and motion-producing de vices in the corresponding projector in which a strong beam of white light from an incandescent lamp, after passing through the three devices, is projected on the screen as one or more mobile im ages depending in form, colour and motion upon the positions and movements of the various keys. A skilled player may select to play a silent visual composition previously written by another artist and recorded by means of a special notation system. The instrument has also been used for visual accompaniments to music, dance and drama, in the latter instance permitting projected scen ery and a much more delicate control of lighting than is possible by means of the electrician's switchboard. (T. W1.)