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).
Letter to Joseph Lucas Ltd. comparing the design of Hall and Lucas headlamps.
| Identifier | ExFiles\Box 61a\2\ scan0096 | |
| Date | 15th July 1930 | |
| Messrs. Joseph Lucas Ltd. Great King St.{Capt. P. R. Strong} Birmingham. 15th July, 1930. -2- In regard to the Hall lamp the front is removable on opening, but the Lucas front is hinged at the top and has to be held up when opened for bulb changing and focus alteration. In the Hall lamp the requisite dispersion is produced by the front glass (mainly downward) whereas the Lucas has a 4" diameter glass centre to the reflector which produces a diverging cone of circular section. Yours faithfully, FOR ROLLS-ROYCE LIMITED. P. S. The lamp is known as "The Depress Beam Headlamp 10". | ||