The spacing/height ratio of lighting units

In the present paper a method of evaluating the lightdispersing power of a light source is given, together with methods of calculating suitable values of spacing/height ratio from the polar distribution curve of the source. Optimum polar distribution curves corresponding to certain values of spacing/height ratio are shown, and information is given from which the optimum polar distribution curve corresponding to any value of spacing/height ratio may be drawn. A new criterion applicable to polar distribution curves and indicating their suitability for producing uniform illumination is suggested. New methods of testing lighting fittings are described. Suggestions are also made relative to the preparation of technical literature on the subject.