THE characteristic and peculiar colours of the discharge lamps used for street lighting have attracted much interest to this important public service. With the development and research departments of great companies behind it, this branch of lighting has made rapid progress. In a paper read to the Royal Society of Arts by J. M. Waldram on January 17, it was pointed out that the use of these lamps has led to material improvements in our knowledge, leading to a new technique. One of the immediate problems of street lighting is connected with the question of who is to pay for it. It is an anomaly that a national trunk road should be built, drained and maintained at the national expense, and the lighting left to local authorities, each lighting its section according to its own ideas and naturally being sometimes very limited as to the cost. The requirements of the motorist are the most difficult to satisfy. He has when moving at high speed to see every obstruction in the road many feet in advance, whatever the condition of the road surface. Claims have been made that certain lights have more fog-penetrating power than others, but recent experiments throw doubt on this. Experience shows that from the safety point of view, when driving, the spectral colour of the light matters little. In general, recent progress has been made mainly in the direction of lowering the cost of production of the light and thus making more light available, and in distributing it over the road in such a way that it is more helpful to both pedestrians and motorists.