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).
Drawing of two rings.
| Identifier | ExFiles\Box 179\2\ img257 | |
| Date | 17th February 1932 guessed | |
| C 12 / 1 2 | ||