In this article, the author links his own experiences from the 1920s onwards to his 75-year review of London street lighting practice. The article's table gives statistical data about British street lighting at 15-year intervals since 1923-24, which is also presented in a graphic diagram. There is a comparison of electrical and total annual performances for the three main parameters of energy, useful light, and cost. These statistics are analysed briefly, and there is also a supplementary table, on the growth of vehicle lighting of roads by low-voltage electricity, which is not analysed in detail. When the Association of Professional Lighting Engineers (APLE) was formed in 1924, most of Britain's street lighting was supplied from `town gas' supplies, and the number of gas lanterns continued to grow in the 1920s and early 1930s. From 1930 onwards, electric lighting began to displace gas lighting. The changeover was completed some time in the 1950s, though portable gas lights were still used for maintenance work. During the 1950s, many blue mercury lamps were installed, but, in the 1960s, these lamps in turn began to be replaced by yellow sodium lamps. Bulk switching was introduced after 1945, and electronic control from the 1980s on. The article also briefly analyses the economics of street lighting in the UK.
Samenvatting