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).
Recommending the use of frosted glass bulbs in patch instruments.
| Identifier | ExFiles\Box 61a\2\ scan0038 | |
| Date | 26th March 1929 | |
| BY.{R.W. Bailey - Chief Engineer} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} X7800 Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}6/LG26.3.29. Please note that the glass bulbs we recommend for use in the patch instruments will be frosted. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||