ABSTRACT
Automatic projection was controlled by the audio-tape, and the audio-player paused automatically in response to control pulses. An indicator lamp showed that the programme presentation had been halted. As for the production services, one can first generalise about the characteristics governing the retrieval process since these apply regardless of the medium. It is suggested that there are four: reliable; readily available; quickly serviced; and capable of giving a high-quality presentation. The basic design housed no equipment but was fitted with a light as, otherwise, due to the height and length of the walls, the level of illumination would have been far too low for adequate illumination of the work-surface. An aspect of carrel design which overlaps that of a management system for a carrel installation is, for the former, a means of controlling the availability of electrical power and, for the latter, a means of knowing which carrels are occupied or, conversely, vacant.
