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).
Graph showing the drop in M.P.H. reading with a rise in temperature for two types of magnetic speedometers.
| Identifier | ExFiles\Box 165\4\ img104 | |
| Date | 3rd September 1931 guessed | |
| MAGNETIC TYPE SPEEDOMETERS CURVES SHEWING PERCENTAGE DROP IN M.P.H. READING WITH RISE IN TEMPERATURE WATFORD A.T. M.P.H. READING TEMP. DEGREES C | ||