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).
Merits of plain glass bulbs and lamp glasses for headlamps over frosted ones.
| Identifier | ExFiles\Box 61a\2\ scan0220 | |
| Date | 1st February 1934 guessed | |
| C. From Hs{Lord Ernest Hives - Chair}/Wst. c. to Hn.{F. C. Honeyman - Retail orders} 86116 Hs{Lord Ernest Hives - Chair}/Wst.4/MA.1.2.34. HEADLAMPS. Answering your Cl/I.31.1.34., we quite agree that the use of plain glass bulbs and plain lamp glasses will increase the total available light. Frosting the glass for a given wattage inevitably reduced the available lumens of light. We understand that Messrs.Lucas use frosted lamps because they even out the beam. The ordinary polished reflectors can not always be guaranteed to be exactly parabolic, also the lamp bulb glass thickness may be uneven giving a lens effect at various places on the reflector. We doubt whether the frosted glass does anything at all to mitigate dazzle. In view of the fact, however, that the art of both making reflectors and lamp bulbs must have been greatly improved in recent years we propose as suggested by you approaching Messrs.Lucas on the subject of adopting clear bulbs and glasses on our headlamps. Hs{Lord Ernest Hives - Chair}/Wst. | ||