Blueprint showing a cross-section diagram of a Standard Drip Plug.
| Identifier | ExFiles\Box 27\1\ Scan262 | |
| Date | 12th July 1929 guessed | |
| STANDARD DRIP PLUG A R C B D O F L H | ||
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).