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).
Test record for an A.T. speedometer, showing MPH readings at various temperatures.
| Identifier | ExFiles\Box 59\2\ Scan084 | |
| Date | 27th October 1930 | |
| X. 4308, A.T. SPEEDOMETER TEST RECORD. Date :- 27-10-30 Speedometer :- C.83.800 13/52 Remarks :- Speedometer off 20 EX Drive counter Counter revolutions per mile 792.0 (found by actual trial). Correct miles per hour reading when driven at 600 r.p.m. :- 45.4 Temperature (°C) | M.P.H. indicated at 600 r.p.m. exactly. 17.0 | 46.6 20.0 | 46.2 22.0 | 46.0 24.0 | 45.8 26.0 | 45.7 28.0 | 45.5 30.0 | 45.3 32.0 | 45.1 Percent fall of reading between 20°C. and 30°C. 2%.... 9.10.30. | ||