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).
Experiment fitting a 7-ringed piston with a skirt to a 7CA engine.
| Identifier | Morton\M11\ img055 | |
| Date | 24th July 1917 | |
| R.R. 235a (200 T) (S.C. 536. 15-2-16) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 1547. EFC/AT24.7.17. X.2369B.-7 RINGED PISTON WITH SKIRT. This experiment has been fitted to 7CA. | ||