FOR the lighting of tennis courts it is essential that there should be complete freedom from glare and that the light should have a high speed of discrimination. In Philips Technical Review (Eindhoven) of August last, it is pointed out that both these requirements are exceptionally well fulfilled by a lighting system employing sodium lamps. Although no satisfactory method has yet been found for making-quantitative measurements of the disturbing effect produced with different types of light, experience has shown that the presence of a source of light in the field of vision is less disturbing with sodium lamps than with other lamp sources of equivalent total candle power. This is due to the comparatively low luminous intensity of sodium lamps. Several experimenters have also proved that the speed of discriminating objects is quicker with sodium light than with other types of light. The illumination of tennis courts is particularly important in regions with a tropical climate where the heat renders play during the day impossible, and where during the evening, when the atmosphere is cooler, darkness sets in very quickly. Three open-air tennis courts in the Netherlands East Indies were recently equipped with sodium lamps. Good results have been obtained with an arrangement of eight 150 watt sodium lamps arranged in two rows, containing four each, on the sides of the court and situated 20 feet above the ground.