Drawing of a lever-operated valve or drain tap.
| Identifier | ExFiles\Box 137\3\ scan0048 | |
| Date | 23th February 1939 guessed | |
| Rm. {William Robotham - Chief Engineer} 1/BA/FJH. {Fred J. Hardy - Chief Dev. Engineer} | ||
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).