Hand-drawn schematic of a DC motor circuit with a battery.
| Identifier | ExFiles\Box 53\3\ Scan230 | |
| Date | 18th June 1923 guessed | |
| R, F-, +, - | ||
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).