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).
Hand-drawn graph with two curves, supplied by Scintilla & Co.
| Identifier | ExFiles\Box 37\1\ scan 299 | |
| Date | 14th May 1925 guessed | |
| Figure Supplied by Scintilla & Co | ||