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This paper records the experience which has now been gained over three years in the use of high-pressure mercuryvapour lamps in public lighting. The engineering and photometric characteristics of the lamps and the design of the auxiliary apparatus are discussed. The overall characteristics of the lamp and its auxiliaries are given, together with certain peculiarities of street-lighting circuits which affect its performance. The effect of the illuminating engineering aspects upon the realization of the efficiency of the lamp is discussed, and the developments of the theory of street lighting which its use has brought about are indicated. Novel designs of lanterns, which are rendered necessary by the peculiar shape of the source, are described; and special optical, thermal, and constructional problems which arise from the use of the lamps, and also other points which have occurred in practical experience, are recorded.

The paper describes the electrical installation in the Royal Festival Hall and illustrates some of the problems encountered in its design. Lightning protection, the power installations, and the primary, secondary and stage lighting are described, special attention being given to the development of the dimming arrangements for coldcathode lighting. The description of the sound amplification system includes arrangements for hearing-aids, simultaneous interpretation, and an unorthodox type of interval signal. Other features of the installation are the provisions made for B.B.C. sound and television broadcasts, stage signalling, cueing systems and internal telephones.

The object of the paper is to outline briefly the design and performance features of lighting equipment used in television studios. Almost all the lighting equipment, together with the appropriate optical and electrical accessories as used to-day, is the result of considerable development over a number of years in film studios, which may be likened to television studios in so far as lighting requirements are concerned. This does not mean, however, that the similarity of lighting-equipment requirements, convenient as it is, will continue, and indeed there are several original pieces of equipment designed to satisfy the peculiar needs of television lighting.