The high-pressure mercury-vapour lamp in public lighting

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.