The term 'radiophonics' is taken (in the BBC) to mean the production of sounds from natural or artificial sources to convey the mood of a broadcasting programme, but not the creation of musical compositions as such. This monograph describes the BBC's Radiophonic Workshop, the type of work which it undertakes, and the equipment used to create the desired sounds. Since the end product is almost invariably a tape recording, much of the equipment is necessarily concerned with the manipulation of tape recordings using fairly standard equipment. However, in order to carry out some of these manipulations, several ancillary pieces of equipment have been specially developed and these are described. The electronic gunfire effects generator is also described, although it is not strictly a part of the equipment of the Radiophonic Workshop; it was developed for direct, or 'spot' effects in studios some years before the workshop came into being.