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).
Photograph showing a comparison of three numbered engine pistons.
| Identifier | ExFiles\Box 148\3\ scan0406 | |
| Date | 28th May 1931 | |
| P.D.S. / 28.5.31 1 2 3 | ||