From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
The effectiveness of different headlamp and fog lamp configurations for driving in fog.
| Identifier | ExFiles\Box 167\1\ img234 | |
| Date | 13th January 1938 | |
| - 2 - Cx{Major Len W. Cox - Advertising Manager}2/KW13.1.38. (3) A good light for driving in fog. Unfortunately the scheme under review was not able to be tested because there was not any fog, but I believe you would find it a very acceptable scheme because of the necessity of having a sufficiently powerful beam to illuminate the nearside of the road as a guide in fog. If the beam was found to be too far ahead for that purpose one could easily swing the lamp over to the left, as it is on a swivelling bracket. I had the unpleasant experience of being caught in a very thick fog just after Christmas, and was driving our present London Trials Car 3-CP-IO with dipping reflector to the nearside lamp and a Lucas spot light. No matter how I used these lamps I could see absolutely nothing but fog and the scheme was quite useless. This is because the dipped nearside headlight was so bright that the dazzle from the fog was quite blinding and there was obviously too much light to drive with, and because the light from the Lucas fog lamp was of a diffused nature and did not illuminate anything but fog. I feel quite convinced that the scheme as fitted to my car would be far better than that. Your proposal to use a spot lamp having a dipping reflector as an alternative may be very good, and I shall be very interested to hear how this works. You say it will probably provide beam and spread. The beam I think will be definitely desirable, the spread useful if not too much, because if it is too much it will dazzle oncoming drivers. My view was that with the scheme as fitted to my car the beam was provided by the spot light and the spread by the dim filaments. We know here that the spread is not objectionable. That seems to show the position under the three headings mentioned by Rm.{William Robotham - Chief Engineer} (contd) | ||