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).
Two-filament headlamp bulbs and the defects of 'Wood-lites' headlamps.
| Identifier | ExFiles\Box 61a\1\ scan0417 | |
| Date | 30th November 1928 | |
| OY2.R.11.30.28 X4477 November 30th, 1928. TO: Mr. Nadin cc - Mr. Beaver Mr. Ross Mr. Burton Mr. Hives (England) Mr. Robotham (England) Mr. Bailey (England) FROM: Mr. Olley RE HEADLAMPS - SECTION 7460 In response to a request from Mr. Robotham we are sending him a package of 10 two-filament headlamp bulbs, 12 volt 21-21 c.p. These will be despatched immediately. In addition we attach copy of letter from Mr. R.E. Carlson of the General Electric Company which refers to the general subject of headlighting. The "Wood-lites" referred to in this letter are of a type which has several times been introduced (and in each case discarded) in which an elliptical reflector is used with the main axis horizontal and pointing in the direction of motion and the bulb deep set within the lamp. The lens is very small and the glare is reduced by reason of the small visible opening. They seem to suffer from two main defects:- (1) Impossibility of two-filament dimming. (2) Too-sharp cut off of the light in a vertical plane for safe driving. As far as can be seen the present parabolic reflector will remain standard for several years, with increasing demand in the various States for two-filament dimming. Introduced first on the cheaper cars, it is probable that lamps without fore and aft adjustment of the bulb will become popular and will finally be required by State law as the bulb manufacturers progress in making bulbs of accurate focal length. OY. r/ | ||