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).
Hand-drawn graph with two curves related to battery ignition.
| Identifier | ExFiles\Box 37\1\ scan 298 | |
| Date | 13th September 1924 guessed | |
| Battery Ignitions | ||