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).
Two photographs, Figures 1 and 2, showing different types of metal washers or rings.
| Identifier | ExFiles\Box 42\4\ Scan031 | |
| Date | 9th December 1931 guessed | |
| REPORT F/EQ/69. FIG 1. REPORT F/EQ/69 FIG 2. | ||