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).
Graph plotting minutes lost over a period of days for a Smith Motor Type electric clock operating at 12 volts.
| Identifier | ExFiles\Box 164\1\ img258 | |
| Date | 30th January 1939 guessed | |
| SMITH MOTOR TYPE ELECTRIC CLOCK AT 12 VOLTS. MINUTES LOST- DAYS:- AT 9 AT 10 AT 6 | ||