Lighting Research & Technology

The visual problems of drivers on the motorway have been studied by new techniques and compared with the problems on traffic routes, with special reference to the possible need for fixed lighting. By day the visual problems are generally much less severe on the motorways, but the vehicle and the driver have less in hand to cope with emergencies and consequences of an accident are often more grave. By night the information presented to the driver by headlights, reflector studs, rear lights and signals are found to be inadequate and often confusing. Fixed lighting of good quality has been shown to be capable of giving the driver all the information he needs, and it is concluded that a technical case for its installation can be made out. The accident rate on motorways is low at present traffic density, but on motorways abroad where the density is greater high accident rates occurred which have been substantially lowered by the installation of fixed lighting. Technical characteristics for fixed lighting on the motorway are derived from the observed requirements. The paper does not discuss questions of engineering, economics or policy. Some suggestions for guidance and visual signalling on the motorway are discussed in an appendix.

The intention of this paper is to describe the development of stage lighting equipment (dimmers and control excluded) in Britain during the past 25 years, and to indicate the forces which have been and are at work to produce this development. The effects of stage design and economics are considered. The great difference between British and German practice, and the lesser difference between British and the United States practice, are outlined. The post-war influence of the New York theatre on lighting layouts in London's West End is described (without enthusiasm) and contrasted with the happy isolation which financial stringency has ensured to the amateur and little theatre movements.

As our eyes age the amount of light reaching the retina decreases. This is attributable largely to changes in the pupil diameter, to the yellowing of the lens and, to a smaller extent, to a change in the effective path-length of light through the lens. The age variation of retinal illumination is estimated on the basis of published data for standard illuminants A and C, and for three types of fluorescent lamp. In all five cases the small difference found to exist between the light-adapted and dark-adapted eye is greater than differences between the lamps considered. In general, retinal illumination at the age of 60 is about one-third of the value corresponding to an age of 20. The practical significance of the estimate is discussed.

Transactions, Volume 26, Number 1, page 48 (1961)-‘A Note on Quantities of Light’ by J. G. Holmes. In the diagram the extrene right-hand line denoting the Utilance Ratio should terminate opposite Fitting Flux and Utilized Flux.