Suggestions are made from time that the minimum mounting height for head lamps should be lowered. At the request of the International Committee on Illumination the effect of head lamp height on the performance of meeting beams is considered for the extremes in current practice, namely the British and The asymmetrical European meeting beams. It is assumed that whatever the mounting height, the angular setting of the meeting beams remains the same and it is possible that different conclusions would be obtained if the aim of the meeting beams had been varied. Taking on to account observations on seeing distances under conditions of glare, is shown that in clear weather the optimum performance of a meeting beam would be obtained if all the head lamps were mounted at the same height as the drivers eyes. This is an impracticable arrangement lamps have to be higher or lower and the results as a whole show that it is better to mount existing lamps below this level rather than above it. For a given head lamp height, elevation of the drivers eyes above the lamps leads to a more marked improvement with the British lamps than with the European. It is concluded that existing head lamps should never be mounted at a height greater than the eye level of the private car driver, which in Modern cars is about 4 ft. European lamps cannot be mounted with their centres less than 2 ft. above the road without incurring a marked loss in performance. The same lower mounting limit is desirable for British lamps.
Abstract